Offline category pack · 2026-08-12

Home systems

Heating, cooling, water, drainage, home electrical work and the devices that keep a dwelling safe.

This is a dated snapshot. Check the current live page and the documentation supplied with your equipment before you start work. Where either differs from this pack, follow the current manufacturer documentation.

51 published pages. Open a title below. Each page is a complete, self-contained HTML file that can be printed from a browser.

  1. Decide what food is safe after a power cutWhen the power fails, refrigerated and frozen food are at risk. Use temperature readings and ice crystal presence to decide what is safe to eat and what must be thrown away. The safety window depends on how full your freezer is and how long the door stays closed.Version 1 · updated 2026-08-03
  2. Find which alarm is chirping and what the chirp meansA chirp and an alarm are not the same thing, and mixing them up is how people either evacuate over a dead battery or, worse, ignore a real fire. A chirp is a short, repeating sound the device uses to ask for something: a battery, a clean sensor, or, eventually, a whole new unit. A full alarm is loud and continuous, and CPSC's guidance for that sound is simple: leave the home immediately and do not stop to investigate. This page is for the chirp. It walks through finding which alarm in the home is making the sound, reading its model number and its age, and getting from there to the actual cause. What this page will not do is hand you a table that says ‘three chirps means low battery, four means replace the unit.’ That table exists, but a different one exists for nearly every manufacturer and often for every model line from the same manufacturer — Kidde's own support pages do not even give the same number of seconds between chirps for the same condition on two different pages of their own website. Printing one number here would make it wrong for most readers and dangerously confident for all of them. So this page teaches the method: find the unit, read its label, and look up the pattern for that exact model in the documentation for that model. It also covers the one signal worth knowing without a lookup — the end-of-life chirp on a carbon monoxide alarm, which Kidde states plainly will not respond to carbon monoxide while it is sounding.Version 1 · updated 2026-08-04
  3. How do I check if my water heater's pressure relief valve pipe is installed correctlyThis page shows how to find the discharge line that runs from the temperature and pressure relief valve (the T&P valve, or the TPR valve) on a storage-type water heater, and how to look at it for four faults that show up in a lot of homes: a capped or blocked end, a pipe that turns upward instead of running down, an open end that finishes high up instead of low, and threads on the outlet. It needs no tools beyond a flashlight and takes a few minutes. Nothing on this page is touched, moved, or adjusted; you are only looking. What this page will not do is have you lift the test lever on the relief valve. A valve that does not close again after a test releases scalding water into the room, and once that starts there is no way for you to stop it. This page also will not print the exact height, pipe material, or pipe diameter your discharge line should have, because Rheem's own installation instructions and general plumbing practice both treat those figures as specific to the water heater and to your local code, not as one number for every home. If you find a fault, this page tells you to bring it to a qualified plumber rather than fix it yourself.Version 1 · updated 2026-08-03
  4. How do I find the date on my smoke alarm and how old can it be before I replace itA smoke alarm can look perfectly healthy and still be past its working life, because the part that wears out is the sensor inside, not anything you can see or hear during a monthly test. The United States Fire Administration states a single, clear rule for this: replace the whole alarm ten years from its date of manufacture. That date is stamped on a label most people have never looked at, on the back of the alarm, and reading it means taking the alarm down for a minute. This page is only about that one task: finding the date, reading it correctly, and deciding whether the alarm has reached the end of its working life. It does not cover changing the battery or testing the alarm; that procedure, and the monthly test schedule, is a separate page. A carbon monoxide alarm looks similar on the wall but is a different device with a disputed service life, and this page does not cover it either. What this page will not do is tell you how to read an encoded serial number, because a smoke alarm's manufacture date is normally printed in the open on the label rather than hidden inside a scheme a reader has to translate. Kidde's own support documentation states plainly that the manufacture date code is stamped on the label on the back of the alarm, not buried in a code only the manufacturer can decode. The one real complication is the alarm with a sealed, long-life battery: the United States Fire Administration's own maintenance guidance tells the owner of that type to replace the whole unit according to the instructions of the manufacturer, rather than giving the same flat ten-year figure it gives for the other two types, so this page names that difference instead of smoothing it away. A hardwired alarm is covered as far as reading the label; the National Fire Protection Association says a qualified contractor should do the replacement of a hardwired unit, so this page stops there. If the label is missing, damaged or unreadable, this page tells you to treat the alarm as unknown in age rather than assume it is safe.Version 1 · updated 2026-08-03
  5. How do I insulate the hot water pipes at my water heaterSlipping foam sleeves onto the first few feet of pipe at a water heater is one of the genuinely easy jobs. The sleeves cost a few dollars, they push on by hand, and the only cutting is with a kitchen knife. This page covers the pipe you can reach standing on the floor next to the unit, which is where most of the heat is lost and where the work needs no access equipment. It does not cover pipe in a crawl space, pipe in an attic, or anything that involves getting off the floor. The number that matters on this page is not the R-value. It is how far the insulation has to stay away from the vent pipe if your water heater burns gas, because foam sleeve is a combustible material and a vent pipe is hot enough to ignite it. This page does not print a single separation figure, and that is a deliberate refusal rather than a gap. ENERGY STAR says building codes usually require one inch of clearance from metal flues and two inches from masonry chimneys to any combustible material, including insulation. Rheem says in its own manuals that you maintain the clearances specified on the rating plate, and that where its label and its manual disagree the label wins. The figure that governs your water heater is on your water heater, and if you cannot read it, this is not a job to start. On savings, the honest position is that this page publishes no dollar figure and no percentage. EPA WaterSense states that pipe insulation reduces the rate of heat loss from water sitting in the pipework, and that is a claim we can trace. The specific savings numbers that circulate came from an Energy Saver page on energy.gov which returned 404 when we checked it on 29 July 2026, so they now exist for us only on third-party sites, which makes them unverified by definition.Version 1 · updated 2026-07-29
  6. How do I know which LED bulb to buy? Reading lumens, watts equivalent, color temperature and bulb base size before you shopMost people still shop for a light bulb the way their parents did: by the watts printed on the old bulb. Watts measure the electricity a bulb uses, not how bright it is, and an LED bulb uses far fewer watts than an incandescent bulb for the same amount of light. That mismatch is why a shopper who picks by watts alone often comes home with a bulb that is too dim, too bright, or the wrong shade of white. The federal Lighting Facts label on the side of nearly every light bulb box already answers the real questions: how bright the bulb is in lumens, what color the light looks like, how long the bulb should last, and roughly what it costs to run. This page shows how to read that label and match it against the old bulb already in the fixture, so a shopper leaves the store with the right bulb the first time. It covers the label's brightness, color, cost and life figures, the base size that has to fit the fixture, and whether the fixture needs a bulb rated for a dimmer switch or an enclosed fixture. It does not cover the physical work of installing a bulb, wiring a fixture, or a smart or connected bulb's app features. If a marking is missing, damaged, or hard to read, the safest step is to ask the manufacturer or a lighting retailer rather than guess.Version 1 · updated 2026-08-03
  7. How do I read the label on my hot water heater and figure out what the numbers meanA water heater carries more information than most owners ever read. Beyond the model number and the serial number, the same rating plate — or a second yellow label next to it — lists the tank capacity, the first hour rating or the recovery rate, the input rating, the voltage or the gas type, the maximum working pressure, and the minimum clearance to combustible material. Every other page on this site about your water heater assumes you can find these numbers, and this page is where you find them and write them down. This page does not decode a serial number into a date of manufacture. That is a separate task with its own manufacturer-specific rules, and the record on finding the age of a water heater covers it in full. Use that page once you have the serial number written down here. This page also will not print a generic number for your maximum working pressure, your minimum gas pressure, your voltage, or any other safety-critical figure, because that number belongs to your specific model. Only your own rating plate or your manufacturer's documentation can give it correctly. What this page teaches is which field to look for and where manufacturers put it, grounded in Rheem's and AO Smith's own installation manuals. Read the actual figure from your own plate, write it down, and take it to a professional when you need work done.Version 1 · updated 2026-08-03
  8. How do I safely heat my house when the power goes out?When the power goes out in cold weather, the choice of how to stay warm is the one that can go wrong fastest. Carbon monoxide poisoning and house fires both climb every winter a storm knocks the power out. This page is a short, sourced list: a carbon monoxide alarm to check first, the handful of devices that must never heat an indoor space no matter how cold it gets, how to tell whether you even have electricity to work with, and what is left once you do not. Every rule on it traces to CDC or CPSC, named next to the rule it supports. This page does not repeat two things covered elsewhere on this site. It does not give the outdoor placement for a portable generator, which is on the generator placement page, and it does not give the full pre-storm checklist, which is on the storm readiness page. It starts from the moment the lights are already out and you are choosing how to keep the house warm, and it stops at the point where a heating system needs a qualified technician.Version 1 · updated 2026-08-03
  9. How do I store emergency drinking water for my household?An emergency water supply is water you keep on hand for a disaster or a service failure. The CDC recommends 1 gallon of water per person per day, with a minimum of 3 days and a target of 2 weeks stored at all times. The hard part is not buying the water — it is keeping track of it and replacing it before it goes stale. Bottled water takes care of itself until the expiration date. Water you fill into containers yourself needs to be replaced every 6 months, which is why this page is as much about the calendar as it is about the containers. A storage routine that works is the routine you do the same day every six months, and this page gives you the steps to set that up.Version 1 · updated 2026-08-03
  10. How hot should my hot water be and how do I check itThis page is about measuring the hot water your taps actually deliver, with a thermometer, and writing the number down. It needs no tools you cannot buy in a supermarket and it takes about twenty minutes. The reason to bother is speed: CPSC publishes that most adults suffer third-degree burns after two seconds in 150 degree water, that burns also occur after six seconds at 140, and after thirty seconds at 130. A small child or an older adult is burned faster than that, and a scald is the one household injury that happens before you can react to it. What this page does not do is change anything on the water heater. No thermostat, no control, no valve. It also will not tell you what to set your water heater to, because the authorities genuinely disagree and this site does not split the difference. CPSC urges people to lower their water heaters to 120 degrees Fahrenheit to reduce scald injuries. CDC says to store hot water above 140 degrees Fahrenheit, and OSHA says the same, because that is the floor for controlling Legionella bacteria in the pipework. Both positions come from federal authorities, both are about a real way people get hurt, and averaging 120 and 140 would produce a number that nobody stands behind. The manual for your own water heater is the document that governs your unit. What this page gives you is the measurement, so that when you read that manual you are holding a real number instead of a guess.Version 1 · updated 2026-07-29
  11. How often to test well water and what to test it forA private well is not covered by the rules that protect public water systems, and no government agency tests it for you. Testing on a fixed schedule is the only way to know whether your well water is safe to drink. Bacteria, nitrate, arsenic and radon can all be present with no color, taste or smell to warn you. This page covers a fixed annual and three-year testing schedule, situations that call for testing sooner, and how to read a laboratory result. It does not cover well repair or water treatment. Follow the sample collection instructions your laboratory gives you for each test. If a result exceeds a health guideline, contact your local health department or a certified water-treatment professional.Version 1 · updated 2026-08-04
  12. How old is my carbon monoxide detector and when do I replace itA carbon monoxide alarm has a sensor with a finite working life, and it can reach the end of that life while still looking perfectly healthy on the wall. This page covers three things: the date of manufacture on the back label, the end-of-life signal that a fresh battery will not silence, and swapping the unit out. It is not about what to do when the alarm is actually going off. If your CO alarm is sounding right now, stop reading and get everyone outside into fresh air, then call 911 from outside. CPSC is explicit that you do not go looking for the source and you do not go back in until the responders say you can. How long a CO alarm lasts is genuinely disputed, and this page publishes the disagreement instead of picking a winner. CDC says to follow the manufacturer's instructions or replace the detector every five years. Kidde, one of the largest manufacturers, says its own alarms have a proven life of seven to ten years depending on the model, that everything it built from 2013 onwards is a ten-year unit, and that anything older than that is a seven-year unit. CPSC publishes no universal number at all and says the recommended replacement age comes from the product literature or from the manufacturer. Those cannot be averaged into a fourth answer that belongs to nobody. The number that governs your alarm is the one printed on your alarm and in its manual, so this page shows you how to go and find it.Version 1 · updated 2026-07-29
  13. How old is my water heater and how do I read the serial numberNobody asks how old their water heater is out of curiosity. The question comes up when it has started to leak, when a home inspection flags it, when an insurer asks, or when somebody is trying to work out whether to repair it or replace it. This page gets you to a defensible date: find the rating plate, record the brand, the model number and the serial number, photograph the plate, and then get the date from the one organisation that actually knows it. On many units the date is simply printed on the plate and you are finished in five minutes. It is only when the plate gives you a serial number and nothing else that the rest of this page matters. What this page will not do is hand you a decode table for every brand, and the reason is worth stating plainly. A date code is a manufacturer's private scheme, and the only correct version of it is the one the manufacturer publishes. Rheem and Bradford White both publish theirs on their own websites, so this page can cite them and does. AO Smith publishes no scheme at all, only a lookup that takes your serial number and returns the date, and every AO Smith decode table returned by searching on 29 July 2026 was a third-party site. Those third-party tables did not agree with each other about which digits carry the year, which is exactly the failure mode this site exists to avoid. If your brand has not published a scheme, the honest answer is the manufacturer's own lookup or a telephone call, and that is what this page tells you to do.Version 1 · updated 2026-07-29
  14. How to bleed a radiator that is cold at the top and warm at the bottomA radiator that is cold at the top and warm at the bottom almost always has air trapped inside it. The air collects above the water, keeps the top of the panel from heating up, and leaves the room cool while the boiler runs longer than it needs to. Letting that air out through the small valve at the top corner of the radiator is called bleeding, and it needs a key that costs very little and about a minute of actual work per radiator. Most of the job is waiting, because the heating has to be off and the radiator cold before you open anything. This page gives the sequence and the boundary, and it prints no numbers you would have to trust. It does not print the pressure your boiler should show afterwards, because that figure belongs to your boiler and your installation and not to the radiator. It does not print a waiting time either: two manufacturers publish different ones, and that disagreement is recorded on this page rather than averaged away. If your radiator is cold at the bottom instead of the top, this is the wrong page, and the boundary section says what it is telling you instead.Version 1 · updated 2026-07-29
  15. How to change landscape light bulbs and work out if my transformer can take themGarden lighting fails in a boring, predictable way: a lamp dies, someone puts in whatever was on the shelf, and three years later the transformer is running warmer than it should on a load nobody has ever added up. This page does the two jobs together. You unplug the transformer, change the lamps, and then total what the system now draws and compare that total with the rating printed on the transformer itself. The whole procedure lives on the 12 volt secondary side, and the only thing you do to the household supply is pull a plug out of an outdoor socket. On the number that matters, the honest answer is that it lives on your equipment and not on this page. Kichler publishes the rule plainly: the total VA of the system should not exceed the wattage value of the transformer. Hinkley asks for the same total plus some spare capacity for fixtures added later. Neither of them publishes a percentage, and neither of them publishes a derating of the transformer's rating for a long cable run — so this page publishes neither, and it says so rather than borrowing a figure from somewhere that never measured it. What you will get here is the method, the two published values we could actually trace, and a clear line at the point where the job becomes an electrician's.Version 1 · updated 2026-07-29
  16. How to change the air filter in a furnace or central air conditionerChanging the air filter is the one maintenance task on a central heating and cooling system that a householder can do without tools, and it is the task most often skipped. ENERGY STAR asks you to inspect the filter once a month and to change it at least every three months. A blocked filter slows the airflow, raises the running cost, and can damage the equipment. This page gives the sequence, the two intervals that come from a government source, and the two values that no general source can supply for your equipment. Filter size and the highest efficiency rating your system will accept are specific to your model. Both are marked unverified here on purpose.Version 1 · updated 2026-07-28
  17. How to change the battery in a smoke detector and test itA smoke detector that chirps once a minute is almost always asking for a battery, and the change itself takes about two minutes. The part people skip is the date. Every smoke alarm carries a date of manufacture on its back label, and the U.S. Fire Administration says the whole unit has to go ten years from that date. A new battery does not reset that clock. So this page does the date check first and the battery second, because there is no point buying a battery for an alarm that is already finished. What this page will not do is tell you which battery to buy. The batteries a given alarm accepts are listed by the company that made it, and NFPA is explicit that you use those and not a substitute, so that value is published here as an instruction to go and read your own label. The page also stops where the reach stops: it covers an alarm you can touch from the floor or from a stable step stool, and nothing higher. Hardwired alarms are covered as far as the backup battery and no further, because the mounting plate and everything behind it is an electrician's work.Version 1 · updated 2026-07-29
  18. How to check a fire extinguisher at home and read the gaugeA fire extinguisher is one of the few safety devices in a house that gives no signal when it stops working. It loses charge slowly, its seal gets snapped by a knock, or it quietly ends up behind the recycling bin where nobody can reach it in the ten seconds that matter. This page is the walk-round: the gauge, the safety pin, the tamper seal, the label, the cylinder and the place it is kept. It needs no tools and it does not ask you to take anything apart. It is not a page about putting a fire out, and it will not tell you to squeeze the handle to see whether the extinguisher still works. First Alert's own manual for its residential dry chemical models says in capitals that you must not, because a unit that has discharged even briefly will lose charge and will not be full when you need it. How often you are meant to do this is genuinely disputed, and this page publishes the disagreement rather than picking a winner. First Alert's user's manual for the FE5GR, FE10GR and FE1A10GR dry chemical extinguishers says to inspect the extinguisher once a week. Kidde, another major manufacturer, says on its own support site that fire extinguishers should be visually inspected once a month. OSHA does require a monthly visual inspection, but that is 29 CFR 1910.157(e)(2) and it governs workplaces, not your kitchen. Averaging a week and a month gives a figure neither manufacturer stands behind, so the interval that governs your extinguisher is the one in the manual that came with it. This page also prints no expiry date and no universal replacement age, because the standard everybody quotes for those is NFPA 10, a document you have to buy, and a number reachable only as somebody else's summary of a standard they may not have read is not a verified number.Version 2 · updated 2026-08-06
  19. How to clean a clogged faucet aerator when the water flow drops or sprays sidewaysWhen one tap goes weak, or the stream splits and sprays off to one side, the cause is almost always the aerator: the small screened insert in the end of the spout. It fills with grit from the supply and with limescale from hard water, and it is the cheapest thing in the house to fix. This page removes it, cleans it, and puts it back, and it does the whole job with a cloth and a soft brush. The part of this job that is genuinely hard is not the cleaning. It is knowing what you are holding. Aerator threads run male and female across at least seven metric sizes and five imperial ones, some taps hide the aerator inside the spout so that it only comes out with the maker's own key, and the manufacturer of the aerator and the manufacturer of the tap flatly contradict each other on whether vinegar is safe to soak one in. This page will not print a thread size for your tap and it will not pick a side on the vinegar question. It shows you how to read the answer off the part in your hand, and it names both manufacturers so you can go to yours.Version 1 · updated 2026-07-29
  20. How to clean out a sump pump pit and check the check valve so the pump stops cyclingA sump pit collects ground water, and over months it also collects the things ground water carries: fine sediment, and sometimes gravel that has worked its way in around the liner. None of that is a fault. It is what a hole in a basement floor does. The other half of this page is the part of the sump system a simple fill test does not reach: the discharge check valve, a one-way fitting on the pipe above the pump that is supposed to stop water already pushed up the pipe from running straight back down into the pit the moment the pump switches off. Liberty Pumps' own installation manual lists a check valve that will not close as a documented cause of a pump that cycles every minute or runs when nobody has used a fixture, because the pump keeps re-pumping water that just fell back in. This page cleans the pit and checks that valve. It does not replace the fill test on Testing a Sump Pump, and it does not cut or reglue the discharge pipe: opening the check valve here only applies where the installation already has a union, the kind of fitting a pump maker installs so the valve can be freed by hand rather than by a saw. Where there is no union, or the check valve will not come free, the page stops and sends the reader to a plumber or a pump dealer rather than guessing with a hacksaw.Version 1 · updated 2026-08-04
  21. How to clean the outside AC unit / condenser coil before summerThe metal fins on the outside of your air conditioner or heat pump collect dust, pollen, grass clippings and leaves over a year. A layer of buildup on those fins makes the system work harder to move heat, and a badly blocked coil is a common reason a central air conditioner runs but does not cool well. ENERGY STAR lists cleaning the evaporator and condenser coils as part of its seasonal maintenance checklist, and Carrier and Trane both publish the outdoor half of that job as homeowner-level work, done with the power off. This page covers the two things a homeowner can safely do: clear the space around the cabinet, and rinse the fins from the outside with a garden hose. This page never covers the refrigerant lines, the compressor, or any part inside the cabinet — that work needs a licensed technician. It does not give one clearance number either: Carrier and Trane publish slightly different figures for their own equipment, and the number that applies to your unit is the one printed on it. It also sets no size for how much a bent fin has to be before you stop and call someone; that judgement call belongs to a professional who can see the coil in person.Version 1 · updated 2026-08-04
  22. How to clear a blocked condensate drain on a central air conditionerWater pooling near your indoor air conditioning unit is almost always caused by a clogged condensate drain line. As your system cools your home, it also pulls moisture out of the air and drains that water away through a small plastic pipe. Dust, dirt and the occasional spider web collect in that pipe and eventually block it. Many systems have a safety float switch that shuts the whole unit off once the drain pan starts to fill, and a homeowner who does not know that switch exists can read a perfectly working safety feature as a dead system. This page shows you how to clear the line yourself, with a wet/dry vacuum from the outside and distilled vinegar from the inside — the same two DIY steps Carrier and Trane both publish for their own equipment. It also says where to stop. If the drain pan has cracked, if water still will not flow after you flush the line, or if the system does not restart once you restore power, this page tells you to call an HVAC contractor rather than force the issue. Some homeowners also pour bleach or a shop-bought drain cleaner down the line; neither Carrier nor Trane states that this is safe for the pipe, so this page does not say so either, and it routes that question to the manufacturer or a contractor instead of guessing.Version 1 · updated 2026-08-04
  23. How to descale or flush a tankless water heater, and whether vinegar or a CLR-type descaler is safe to useA tankless (on-demand) water heater has no tank for sediment to settle in, but hard water still leaves mineral scale inside the heat exchanger every time the burner fires. Left alone, scale narrows the waterways, cuts the flow of hot water, and can trigger an overheating error code. Clearing it out is called descaling, or flushing, and every major tankless maker publishes a version of the same basic job: close off the water heater, circulate an acid solution through the heat exchanger with a pump and a bucket, then rinse. The steps are similar across brands. The numbers are not. We read Rinnai, Navien, Noritz and Rheem's own instructions, and no two of them agree on the descaling agent, the quantity, or how long to run the pump — Rinnai's own two documents even disagree with each other. Rheem states that a qualified service technician must do this work on the model we read. This page will not print a single figure that might be wrong for your water heater. It shows the shared shape of the job and sends you to your own documentation for every number.Version 2 · updated 2026-08-04
  24. How to find out which outlets a GFCI protects, and why a dead bathroom or garage outlet is often a GFCI that tripped somewhere elseA GFCI receptacle is the outlet with the TEST and RESET buttons on its face, and it almost never protects only itself. CPSC describes a receptacle-type GFCI as protecting whatever is plugged into it and other electrical outlets further down stream in the branch circuit, and Leviton's own installation leaflet adds the part that catches people out: those protected outlets can be in different rooms. Nothing on the face of a protected outlet has to say which device controls it. That is why a dead outlet in the garage is so often a GFCI that tripped in the bathroom, and why people replace a working outlet, or call a trade, for a job that is one button press. This page makes the map. You press TEST once, walk the building with a table lamp, write down every outlet that goes dark, put a label on each of them, and press RESET. It is a lamp, a list and a sheet of stickers, and it needs no cover plate removed, no wire touched and no tool other than a pen. It does not cover the monthly test of whether the device still works — that is a separate job with its own page — and it does not cover a GFCI that refuses to reset. It prints no voltage, no current and no trip threshold, because a map needs none of them and this site does not publish a safety-critical number it cannot trace to a primary source.Version 1 · updated 2026-08-06
  25. How to find your main water shut off valve and check that it actually worksEvery water emergency starts with the same instruction: turn off the water. That instruction assumes two things most households have never checked — that somebody knows where the main shut-off valve is, and that the valve still closes. Neither is safe to assume. FEMA's community preparedness handouts put "locate and label main water cutoff" on the outage checklist for exactly this reason, alongside a reminder to keep any special tool it needs stored nearby. A valve that nobody has turned in fifteen years is a valve nobody has proved. This page is the half hour that decides how bad a burst hose or a split pipe gets. You find the valve, work out which of the two common types it is, close it, prove at a tap that the water really stopped, open it fully again, and then label it and tell the rest of the household. It does not cover replacing a valve, and it does not settle who may operate the valve in the box at the kerb — utilities genuinely disagree about that one. Seattle Public Utilities says plainly that older meters need a special tool and only its own crews operate them; DC Water publishes steps for lifting the cover and closing the valve itself. Ask yours. If your valve will not turn, this page tells you to stop, and why stopping is the right answer.Version 2 · updated 2026-08-12
  26. How to fix a leaky faucet that drips from the spout or weeps around the handleA tap drips because one soft part inside it has stopped sealing — a washer, an O-ring, or the whole cartridge. It is not an expensive fault and it is not an urgent one, but it is a steady one: EPA reckons a faucet dripping once a second throws away more than 3,000 gallons in a year. The mechanical work is easy. The part that defeats people is buying the right part, and that is what most of this page is about. There are four internal designs in ordinary household taps and they fail differently, so the first job is to work out which one you are holding. After that the difficulty is that a cartridge is keyed to a brand and very often to a single production range within that brand, and no page can look at your sink and tell you which. So we will not print a part number, and we will not print a tightening figure for the bonnet nut either. What we will do is show you where the leak points, how to get the old part out intact, and how to reach the maker's own parts diagram — including the trap where the number stamped on your spout turns out to be a plumbing standard rather than a model number.Version 1 · updated 2026-07-29
  27. How to fix a toilet tank that fills too high or too low, and set the correct water level at the fill valveA toilet tank that fills past the overflow tube keeps sending water down the drain long after the flush is done, and it usually reads to the household as "the toilet is running" or a water bill that crept up for no obvious reason. The fix is almost always a small adjustment at the fill valve, the part inside the tank that lets water back in after a flush and shuts off again once the tank is full. EPA's WaterSense program, which publishes water-efficiency guidance for toilets, tells facility staff to check that the refill water level sits below the top of the overflow tube and to lower the float if it does not. The same float that runs too high when it is set wrong can also be set too low, which shows up as a weak or incomplete flush instead of a running one. What this page will not do is give you one exact water level for every toilet, because fill valve makers print their own target line on the valve, and it is not the same distance below the overflow tube from one brand to the next. So this page teaches you to find the mark inside your own tank first, and gives EPA's general guideline only for when no mark exists. It covers the common screw, dial and clip adjusters, and tells you plainly when a fill valve's design puts the job outside a simple adjustment, at which point the honest answer is to read that valve's own instructions rather than guess.Version 1 · updated 2026-08-04
  28. How to fix an outside tap that drips or won't shut off by replacing the washer and the packing inside the stemA frost-proof outdoor tap — also called a frost-free faucet, a freezeless faucet, or a sillcock — looks like an ordinary hose bib from the yard, but the part that actually shuts the water off sits far back inside the wall, in the warm part of the house. Arrowhead Brass, a maker of these fixtures, builds that shutoff point at the far end of a single long stem, and depending on the model that stem can run roughly 7 to 18 inches into the wall. The 2 to 14 inch figure printed in Arrowhead's guide is the wall-thickness code in the model number, not the stem itself, so measure yours rather than assume. A drip from the spout when the tap is closed almost always means the washer at that far end has worn out. A drip or a weep around the handle instead points to the packing, a seal that sits where the stem passes through the nut you turn the handle against. Both parts sit on the same stem, and neither one can be reached from the front of the tap without pulling that whole stem out first. This page covers the method: how to find where the tap leaks, how to shut off the water, how to remove the stem, and how to fit a new washer and new packing. It does not cover a plain outdoor hose bib with no long stem — for that ordinary compression tap, see Stopping a Dripping Tap instead. It also does not print a part number or a torque figure for the packing nut: a repair kit is specific to the maker and the model, and Arrowhead Brass alone sells at least six different hydrant series that use different kits, so guessing at a number here would be more likely to be wrong than useful. Measure your stem, find your maker, and match the part — the method on this page gets you to that point.Version 1 · updated 2026-08-03
  29. How to flush a water heaterSediment settles at the bottom of a storage water heater over time, and it is the most common cause of a rumbling or popping noise from the tank. This page walks you through draining a storage-type water heater, electric or gas, to flush that sediment out through the drain valve. It also covers refilling the tank afterward so you do not restore power to an empty tank. This page does not give lighting steps for a gas control: those steps differ by manufacturer and model and belong in your water heater's own manual. It also does not have you open the temperature and pressure relief valve to add air during the drain, because that valve can fail to close again; a hot water faucet elsewhere in the house does the same job more safely. If the drain valve will not close after the flush, this page tells you to call a plumber rather than force it.Version 2 · updated 2026-08-04
  30. How to get the house ready for a storm and a power outageThis is the list of things worth doing in the day or two before a forecast storm that might take the power out. It covers the outside of the house, the food in the refrigerator, the water you drink, and the one number on this page that will actually hurt someone if you get it wrong: how far away a portable generator has to stand. Every figure here comes from CDC, CPSC or the National Weather Service, and the authority is named next to each one so you can see where it came from. Two things this page deliberately does not do. It does not tell you how to connect a generator to the wiring of the house, because that is a licensed electrician's job and a generator wired in without a transfer switch can push power back out into the utility lines and kill a lineworker. And it is not an evacuation plan or a flood plan: if a flood or an evacuation is on the table, your local emergency management office knows your address and this page does not. What it will give you is a sequence you can work through with a phone in one hand, and a plain statement of where its knowledge stops.Version 1 · updated 2026-07-29
  31. How to keep water pipes from freezing in a cold snap, and what to do if one has already frozenDemand for this page arrives on a forecast, which is the worst possible moment to start reading. So it is written in the order the cold arrives: find the shut-off valve first, prepare the house second, get through the cold snap third, and deal with a pipe that has already frozen last. The order is deliberate. The advice everyone repeats — leave a tap dripping — is the last measure on the list, not the first, and it does nothing for a pipe in a draughty crawl space that nobody has ever insulated. One instruction on this page is absolute and it is the reason the page exists. Never put an open flame near a frozen pipe. Seattle Public Utilities explains why: a blowtorch can make the water inside a frozen pipe boil and cause the pipe to explode, and every open flame in a house is a fire risk and a carbon monoxide risk on top of that. The CDC says the same thing more briefly — if your pipes do freeze, do not thaw them with a torch. This page will also tell you where its knowledge stops: no source read for it publishes an outside temperature that triggers any of this, and the sources disagree about how warm to leave an empty house, so both figures are printed with the authority that published each one.Version 1 · updated 2026-08-12
  32. How to replace a shower head and read the GPM flow rate stamped on the new oneA showerhead loses spray force over the years as mineral deposits clog its holes, or a household simply decides to cut its water use. EPA's WaterSense programme estimates that the average family could save about 2,700 gallons of water a year, and more than 330 kilowatt hours of the energy used to heat it, by fitting a WaterSense labeled showerhead. The mechanical part of the job is a short unscrew-and-rescrew onto the shower arm already in your wall. The part most people get wrong is the tape. This page will not tell you the thread size of your shower arm, because household shower fittings are not standardized enough for one number to be safe to print, and it will not tell you the flow rate of the showerhead you buy, because that number is set by the manufacturer and marked on the product itself. What this page does give you are the two ceiling numbers that govern every showerhead sold in the United States — the federal maximum and the lower WaterSense maximum — so that when you read the number on your own new showerhead, you know what it means.Version 1 · updated 2026-08-04
  33. How to replace a thermostat and get the wires on the right terminalsSwapping a room thermostat is an afternoon of careful labelling wrapped around about ten minutes of actual work. The wires behind the old unit carry a 24 volt control signal rather than the supply that runs the furnace or the air conditioner, and the entire job is deciding which of those wires belongs on which lettered terminal of the new unit. That decision is the page. Everything else is packaging. Here is the part most pages skip: nobody can tell you which wire goes where, and this one will not pretend otherwise. Resideo says outright that there is no standard for which colour wire controls which function, and that every wire must be identified by the terminal it came off and never by its colour. So the method is to photograph what you have before you disturb it, label each wire with the letter it was attached to, and match letters to letters on the new unit using that unit's own guide. There are also four things you may find behind the old thermostat that change the answer: three of them end the job and send you to a professional, and the fourth — heat pump against conventional — is the one that damages a control board when somebody guesses. All four are checked before a single wire comes off.Version 1 · updated 2026-07-29
  34. How to replace a worn toilet flapper when the toilet runs, ghost flushes, or leaks silently into the bowlA toilet that hisses long after the flush, refills by itself in the middle of the night, or simply costs more than it used to, is usually failing at one rubber part: the flapper that seals the bottom of the tank. EPA's WaterSense programme puts most toilet leaks down to old or worn-out flappers, and reckons a leaking household loses more than 9,300 gallons a year. The part costs a few dollars, the job needs no tools, and the whole thing is over in about half an hour. What this page will not do is tell you which flapper to buy. Flappers come in a standard and a large size, keyed to the flush valve underneath them, and the fit is further keyed to the toilet — Korky's own answer is that its repair kits are universal across brands, immediately followed by an instruction to check what size your toilet uses. So this page teaches you to read the size off the toilet in front of you and to take the worn part with you, rather than printing a number that is right for someone else's toilet. It also does not print a chain length or a tank water level, because both are set by fit against your own hardware and neither can be traced to a source that covers it.Version 1 · updated 2026-07-29
  35. How to start up a garden irrigation or sprinkler system in springAn in-ground irrigation system sits full of trapped water and empty pipe over winter, and both Rain Bird and Hunter Industries publish the same core warning for starting it again: open the supply valve slowly. A valve opened too fast sends a pressure surge, called water hammer, through pipe that has been empty, and both manufacturers say this can burst a pipe or damage a valve. This page walks through a spring start-up in that order — checking that the soil is no longer frozen, checking the valves and the controller, opening the supply valve slowly, checking the water pressure, then checking every sprinkler head one station at a time for the faults EPA's WaterSense program and both manufacturers describe: a head that does not rise fully, a head that leans, a head that is missing, misting from a head, and a head aimed at a path or a driveway instead of the lawn. This page assumes a residential system fed from a public water supply, with a supply valve, a controller and sprinkler heads. It does not cover a well-fed system, a system with narrow drip tubing and emitters instead of heads, or a repair beyond flagging a fault for a professional — replacing a valve, a backflow preventer or buried pipe is a job for an irrigation professional. If your water pressure reading is far outside the range this page gives, or you find a cracked pipe, valve or backflow preventer body, stop and read Professional boundary before you go any further.Version 1 · updated 2026-08-04
  36. How to tell if a surge protector still works, and when to replace a surge protector or power stripA surge protector is the power strip you bought because the box said surge protector, and the thing almost nobody is told about it is that it does not stop working the way a light bulb stops working. The protective parts inside are consumable. They take the hit, they wear, and one day they are finished — and depending on how your particular unit was designed, the outlets may go on delivering power exactly as before. NIST's consumer guide says so plainly: some protectors cut the output power off completely when the protective element fails, and others disconnect the failed element and maintain the power output. You cannot see which of the two you own by looking at the outside, and your equipment will never tell you. What you can do is read the indicator lights, read the label, read the sheet that came in the box, and know what each of them is and is not saying. This page covers the outside of the unit only. Nothing is opened, nothing is wired, and no meter is used. It will not print a joule rating, a service life in years or a replacement interval, because those belong to your model and to your own documentation — and where the sources disagree, as they do about how long a surge protector lasts, this page prints the disagreement instead of an average. If the ground light on your strip is dark, the page stops and sends you to a licensed electrician, because that light is reporting on the outlet in your wall rather than on the strip. Protection for a whole building is not covered here. What you get is a repeatable check you can run on every strip in the house in one pass, and an answer to the only question that matters: is this thing still protecting anything?Version 1 · updated 2026-08-06
  37. How to tell if you have a hidden water leak using your water meterA water bill that jumps for no clear reason often means a leak somewhere in the plumbing, and the reason it is easy to miss is that it can be silent: a worn toilet flapper, a cracked irrigation line, or a slow drip inside a wall. EPA's WaterSense program puts the average household's leaks at more than 9,300 gallons of water wasted a year, and some homes lose 50 gallons a day or more without anyone noticing. The water meter settles the question with no tools beyond what most households already own: read it, use no water for two hours, then read it again. If the number moved, water went somewhere. The meter's own leak indicator, a small dial, star or triangle that turns with any flow at all, will often show it happening in real time. This page proves whether a leak exists and gets you halfway to where it is, using the home's main shutoff valve as a second checkpoint: close it, and if the meter is still moving, the leak sits between the meter and the house rather than inside it. It does not find the exact fixture — for that, see the linked pages on a dripping tap, a worn toilet flapper and a blocked drain. It does not cover a leak on the far side of the meter, in the line the water utility owns; that call goes to them.Version 1 · updated 2026-08-03
  38. How to test a GFCI outlet with the TEST and RESET buttons, and what it means when it will not resetA GFCI receptacle is the outlet with the TEST and RESET buttons on its face, and it is usually the one in a bathroom, a kitchen, a garage, a basement or outdoors. It watches for current leaving the circuit through something that is not the return wire — a person, for example — and it cuts the power in a fraction of a second. It only protects anyone for as long as it still works, and it can stop working with no outward sign at all. That is why the CPSC and the device makers both ask you to press the two buttons on a schedule. The whole test is a lamp, a press, a look and a second press. This page covers that test and stops there. It does not cover replacing a GFCI receptacle, wiring one, or any work behind the cover plate. Never open the service panel and never take a receptacle out of its box: that is a licensed electrician's work, and a device that fails this test is a call to one rather than a repair. The page also does not print the leakage current the device responds to as a specification, because the standard that sets it, UL 943, is not a public document. Where a number belongs to your particular device, the page sends you to the instruction sheet that came in the box with it.Version 1 · updated 2026-07-29
  39. How to test a sump pump and its float switch before the wet seasonA sump pump spends most of its life doing nothing, and then it has one job on one bad night. The failure people actually meet is not a burnt-out motor: it is a float that cannot move because debris has built up around it, or a discharge line blocked with ice or leaves, or a plug that worked its way loose months ago. All three are visible in ten minutes, and all three are invisible until you go and look. Zoeller's own installation instructions ask for an inspection and test of the system at least every three months, which is roughly four visits a year for a machine whose failure costs you a basement. The test on this page is the honest one: fill the pit with water and watch the pump do what it does when it matters. It is not the same as lifting the float by hand, which proves only that the switch closes. The page covers the fill test, what to look at while the power is disconnected, and where to stop. It does not print a discharge pipe size, a switch level, a temperature limit or an electrical rating, because every one of those belongs to your pump and your installation, and the label on the pump has them. Changing the discharge line is not on this page either — that is regulated work and it belongs to a plumber.Version 1 · updated 2026-07-29
  40. How to test a sump pump battery backup and check the batteryA sump pump's battery backup only earns its place during the exact event most likely to defeat the primary pump: a storm that cuts the power. It sits untested for months at a time, because testing it on purpose means creating a small power cut, and most people never do that. This page walks through that test, whether the system is branded Zoeller, Liberty Pumps, or just called a basement watchdog by the people who own it: disconnect the main power, let the battery run the pump alone, and watch it do the job it exists for. It also covers a monthly look at the battery itself, since a corroded terminal or a battery near the end of its life is the most common reason a backup system fails on exactly the night it is needed. This page does not print a battery group size, a charger output rating, or a maximum pumping height, because those numbers are different for every make of backup system, and the label on your unit or your own installation manual has them. It does not cover installing a new backup system, only testing and checking one that is already in place. Two manufacturer manuals were read for this page, one from Zoeller and one from Liberty Pumps, and on how often to test they disagree; that disagreement is printed here rather than averaged away or quietly picked for you.Version 1 · updated 2026-08-03
  41. How to test your home for radon with a short-term kit, what closed-house conditions are, and what the results meanRadon is a radioactive gas from rocks and soil that seeps into buildings. It has no colour, smell or taste. No amount of radon exposure is safe. Radon causes lung cancer, the second leading cause in the United States after smoking. Most people do not know whether their home has radon. Testing is the only way to know. A short-term radon test runs for two days to 90 days, depending on the kit, in the lowest level of a home with windows and doors closed. Follow the period printed in your kit's instructions. You send the device to a laboratory, which reports the radon level in pCi/L (picocuries per litre). The EPA action level is 4 pCi/L. This page covers testing and reading results only.Version 2 · updated 2026-08-03
  42. How to unclog a slow or blocked drain in a sink, bathtub or showerA drain that empties slowly, or not at all, is almost always blocked close to the fixture. Hair, soap and grease build up in the trap under the sink, or in the short length of pipe behind it, over months rather than overnight. A cup plunger shifts most of them, cleaning the trap by hand shifts most of the rest, and a hand drain auger reaches what is left. This page covers a sink, a basin, a bath and a shower, and it uses two hand tools and no chemicals. It also says where to stop. If every drain in the building is slow at the same time, the blockage is not under your sink and nothing here will reach it. That is a plumber's job, and the page says so rather than sending you further down a pipe you cannot see. We do not print a chemical drain cleaner dose or a temperature limit for your pipe, because neither can be traced to a source that applies to your plumbing.Version 1 · updated 2026-07-29
  43. How to winterize a garden irrigation or sprinkler system before it freezesAn underground irrigation system drains water from its pipes in one of three ways: a manual drain valve you open by hand, an automatic drain valve that opens on its own, or a compressed-air blow-out. Rain Bird's own guide says some properties use a combination — a manual valve on the mainline and automatic valves on the lateral lines running out to the heads. This page covers the first two methods: finding your drain valves, shutting off the water supply, draining the mainline and the backflow preventer, and setting the controller for winter. If your property has both types of valve, expect the job to run toward the longer end of the time estimate below. The compressed-air method is not covered here as a set of steps. Rain Bird's and Hunter Industries' own guides both recommend hiring a licensed irrigation contractor for it, and the two guides do not agree on the maximum air pressure to use — Rain Bird caps it at 50 psi for any system, Hunter Industries allows up to 80 psi for rigid PVC pipe. Where two manufacturers publish different numbers for the same job, this page does not pick one; it sends you to a professional instead, and Professional boundary explains why.Version 2 · updated 2026-08-04
  44. How to winterize an outdoor faucet so it does not burst in winterThe single most expensive misunderstanding in home plumbing is that a frost-free outdoor tap looks after itself. It does not. Arrowhead Brass states it plainly in its own wall hydrant guide: the only cause of a burst frost-proof hydrant is water freezing inside a hydrant that did not drain, and a properly installed one always drains unless a hose or another device was left attached. Woodford says the same about its best-selling freezeless faucet — it will not burst if it is installed correctly and the homeowner detaches the hose. So the hose is not a detail. The hose is the job. The damage is also invisible until spring. Water freezes in the hose first, then works back through the spout toward the valve seat, which on a frost-free tap sits inside the heated wall — so the copper splits inside the wall cavity and you find out when you turn the tap on in April and the ceiling below gets wet. This page removes the hoses, closes the indoor shut-off valve, opens the tap, drains the line through the bleeder cap, and deals with the vacuum breaker that catches people out. It also tells you where to stop: a tap that points upward will never drain and that is a plumber's job, not yours.Version 1 · updated 2026-07-29
  45. Make a home fire escape plan and practise itA home fire escape plan is a simple floor plan of your home that marks two ways out of every room, one meeting place outside, and the location of each smoke alarm. The U.S. Fire Administration says a household can have less than two minutes to get outside once a smoke alarm sounds, so a plan only helps if everyone already knows it. This page walks you through drawing that plan, then through running it as a real fire drill with every household member, including a drill at night. It draws on the U.S. Fire Administration's own Home Fire Escape Plans page and NFPA's own Home Fire Escape Planning page, both government or standards-body sources rather than a single household tip. This page gives you the escape-plan steps both agencies publish and the one figure they name for how often to practice: twice a year, according to NFPA. It answers common searches like "fire drill at home" and "what to do if the smoke alarm goes off at night" in plain language, alongside the exact wording for each step. It does not cover installing a smoke alarm or choosing where to put one; see the related pages on this site for that job. It does not cover an apartment building's or a workplace's posted evacuation plan, since a shared building follows its own plan, set by building management.Version 1 · updated 2026-08-04
  46. Match an extension cord to the appliance it will supplyAn undersized extension cord can overheat and catch fire, even though the appliance works normally. You will read three values printed on the products — the appliance current, the cord gauge, and the cord length — and match them. This procedure shows you where to find them and what to check.Version 1 · updated 2026-08-03
  47. Set a heating and cooling schedule on a programmable thermostatA programmable or smart thermostat can hold a different target temperature at different times of day, so the heating or cooling system runs less while nobody needs it. Setting the schedule itself usually takes ten to twenty minutes once you know the times and temperatures you want. The menu names and the buttons are different on every brand, so this page gives the steps in the order every schedule menu uses and sends you to your own thermostat's guide for the exact button. ENERGY STAR reports that its certified smart thermostats save an average of about 8% of a heating and cooling bill, and a straightforward schedule can save close to 10% a year, on figures the manufacturer Trane attributes to the U.S. Department of Energy. This page does not print one correct setback temperature, because comfort is personal and a deep setback behaves differently on a heat pump than on a furnace or a standard air conditioner. It gives the ranges manufacturers publish, the heat pump caution that is easy to miss, and where to find the exact number for your own equipment.Version 1 · updated 2026-08-04
  48. What do I do during a boil water notice, and what do I do once it is lifted?A boil water notice, also called a boil water advisory or a boil order, is an alert from a water utility or a health department that tap water may carry harmful germs. Most households get the drinking part right and boil or buy bottled water, then miss the rest: ice already sitting in the freezer, the filtered tap on the refrigerator door, a child's toothbrush rinsed under the faucet, and a baby's bath. This page covers what to use instead for every one of those, and what changes if your notice is a do-not-drink notice or a do-not-use notice rather than a boil water notice. It also covers the part most guides skip: what to do once the notice is lifted, since the water sitting in your home's pipes, ice maker and filters does not become safe the moment the notice ends. This page does not give you a fixed number of minutes to flush your pipes, because that figure depends on your own water system and your utility sets it, not a general guide.Version 1 · updated 2026-08-03
  49. What to put in a home emergency kit and how much of itA go bag, a 72-hour kit, a hurricane box, a bug-out bag — whatever you call it, the hard part is not the list, it is the quantities and the fact that a kit assembled once quietly rots. Batteries go flat, bottled water passes its date, and the medication in it is a year out of step with your prescription. This page gives the item list, the numbers the federal agencies actually publish, and a six-month check that takes twenty minutes and is the reason the kit still works when you need it. Every quantity here is traced. One gallon of water per person per day, three days as the floor and two weeks as the target, six months between water changes, two weeks of prescription medication, two weeks of food and water for each pet: all of those are CDC figures and each is attributed on the page. Where there is no federal number — how much formula your infant needs, which of your own medicines can be stored and for how long — this page says so and sends you to a pharmacist, a pediatrician or a veterinarian rather than inventing a figure. It is a packing list with its sources shown, not a survival philosophy.Version 1 · updated 2026-07-29
  50. Where is the water under my hot water heater coming from, and does it mean I need a new one?Water on the floor under a water heater is not one fault. It has six common origins and they do not have the same answer. Condensation is not a leak at all, and A. O. Smith's own gas guide says so in as many words: "Condensation is not a leak and will go away once the tank reaches normal operating temperature." A wet pipe connection at the top is the usual finding rather than the unusual one, and the same manufacturer's installation check states that "Almost all leaks occur at connections and are not a tank leak." A drip from the relief valve discharge pipe is mostly a message about the water pressure in the house. Water that comes from the body of the tank is the one result that ends the argument, because Rheem says that pooling water around the tank body "often indicates internal corrosion that has eaten through the metal, and once a tank begins to deteriorate from the inside, replacement becomes the only safe and cost-effective solution." This page sorts the origin and it repairs nothing. The first instruction is to switch the power off, and that ordering is the point rather than a formality: A. O. Smith's electric guide tells owners to "Disconnect power by opening the circuit breaker or removing the fuses before installing or servicing", and Rheem's own emergency page for a leaking water heater puts the electricity off before the water off. Standing in water beside a live appliance is the part of this job that can kill you, and it comes before you have learned anything at all. Every result that is a leak then routes to a licensed plumber, because this site does not publish water heater repair. The one result that is not a leak — condensation — routes nowhere at all, and separating it from the other five is half the value of the page. The other half is the single sentence that decides what the visit costs: which part was wet.Version 2 · updated 2026-08-12
  51. Where should I put smoke detectors, and how many do I needA smoke alarm only protects the room it can actually sense smoke in, so the count and the position matter as much as the alarm itself. The U.S. Fire Administration and NFPA's own installation guide agree on the same basic layout: one alarm inside every bedroom, one outside each separate sleeping area such as a hallway outside a row of bedrooms, and one on every level of the home, including a basement. A larger home, a long hallway, or an open floor plan can need more than this minimum to give every sleeping area a fast warning. This page turns that layout rule into a room-by-room list for your own home, then walks through the exact spot inside each room. The page also covers the exact spot inside each room: how close a smoke alarm can sit to a cooking appliance without a nuisance trip every time a pan is on the stove, how far it needs to stay from a bathroom door so shower steam does not set it off, and the general area to avoid near an air vent or a corner where trapped air can slow it down. Two of those figures, the distance from a cooking appliance and the distance from a bathroom door, are traced to NFPA's own installation guide, along with the ceiling clearances for a wall-mounted alarm and a pitched-ceiling alarm. The exact distance from a wall corner and from an air vent are not published as free consumer guidance anywhere we could verify, so this page tells you to read those two from the instructions for your own alarm instead of guessing. What this page does not cover is new household wiring: if the spot you choose already has a plate with a wire on it, that connection is an electrician's work, not this page's.Version 1 · updated 2026-08-03