# Why does my water heater pilot light go out now? **URL:** \ **Category:** Factual Questions\ **Created:** [September 23, 2015, 3:46pm UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306 "2015-09-23T15:46:41Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Zsofia](https://avatars.discourse-cdn.com/v4/letter/z/7bcc69/32.png) [@Zsofia](https://boards.straightdope.com/u/Zsofia)\ **Post date:** [September 23, 2015, 3:46pm UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/1 "2015-09-23T15:46:41Z")
I’ve had this water heater for, I dunno, maybe six years now? Used to have the simple kind where relighting it meant a BBQ lighter but this one has the automatic light thing where there’s a knob that has “on pilot off”, a pilot clicker, and a thermostat. It lives outside in its own little metal shed. It’s been problem free since it was installed until a few months ago. Now when we have a heavy rain we lose hot water - not right away, like the next day. And it’s a bitch to relight because you can’t see anything through the little window for love nor money, but even when you’re pretty sure you’ve got it relit it often doesn’t stay that way. If you re relight it and get it on it will be problem free until the next really heavy rain. So what on earth is it? (Besides awful?) ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [September 23, 2015, 4:00pm UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/2 "2015-09-23T16:00:02Z")
I haven’t seen a gas appliance with a pilot in 30 years or more. Back then, the most likely cause was the device that turns the gas off if the flame goes out. Basically a simple thermocouple that holds the supply open so long as it stays hot. If that is the culprit it is cheap and easy to replace. ---
**Author:** ![slash2k](https://avatars.discourse-cdn.com/v4/letter/s/439d5e/32.png) [@slash2k](https://boards.straightdope.com/u/slash2k)\ **Post date:** [September 23, 2015, 4:05pm UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/3 "2015-09-23T16:05:30Z")
How is the water heater vented, and has anything changed on the vent (such as tree growth or debris around it)? ---
**Author:** ![Clothahump](https://avatars.discourse-cdn.com/v4/letter/c/51bf81/32.png) [@Clothahump](https://boards.straightdope.com/u/Clothahump)\ **Post date:** [September 23, 2015, 4:07pm UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/4 "2015-09-23T16:07:02Z")
Has gas pressure in the incoming lines fluctuated? We had a similar problem for a while and that’s what it was diagnosed as. Went away as soon as the pressure stabilized. ---
**Author:** ![Quercus](https://avatars.discourse-cdn.com/v4/letter/q/7ab992/32.png) [@Quercus](https://boards.straightdope.com/u/Quercus)\ **Post date:** [September 23, 2015, 4:17pm UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/5 "2015-09-23T16:17:43Z")
If this was just installed a couple months ago, and you’ve had the problem since it was installed, I think it’s kind of up to the person who installed it to figure out what’s wrong. ---
**Author:** ![doorhinge](https://avatars.discourse-cdn.com/v4/letter/d/a5b964/32.png) [@doorhinge](https://boards.straightdope.com/u/doorhinge)\ **Post date:** [September 23, 2015, 6:15pm UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/6 "2015-09-23T18:15:27Z")
It would be easier to troubleshoot the problem if you supply the make, model number, and serial number. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [September 23, 2015, 6:16pm UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/7 "2015-09-23T18:16:05Z")
I believe he has had it for years and the pilot began going out a few months ago. As another guy mentioned, it has been my experience that the [thermocouple](https://www.labfacility.com/cache/images/rsz/cache/filelibrary/106/library/fileLibrary/2011/5/GH8Q5838_800_600.jpg) is the culprit. If you don’t feel comfortable changing it, that is, if you aren’t familiar with gas appliances, get a plumber to check it out. You just have to unscrew the thermo couple at both ends and screw (or snap) in a new one. ---
**Author:** ![Zsofia](https://avatars.discourse-cdn.com/v4/letter/z/7bcc69/32.png) [@Zsofia](https://boards.straightdope.com/u/Zsofia)\ **Post date:** [September 23, 2015, 6:35pm UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/8 "2015-09-23T18:35:24Z")
I had a plumber restart it twice, much to my fury, because this should so be something we can do and I don’t understand why we can’t see in the window. One plumber told us it was a cracked water heater and it needed to be replaced - my mom convinced me last minute to call Scuzzy Almost Retired Family Plumber who laughed and relit it. So I’m a little gunshy. It vents out the top, no problems there. We do let the backyard get pretty jungly, could that be related? ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [September 23, 2015, 6:40pm UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/9 "2015-09-23T18:40:46Z")
I don’t know what rain would have to do with it, but the symptoms sound like a failing thermocouple. This is a little safety gizmo that sits in or near the pilot flame. When it’s hot, it keeps the gas valve open, but if the pilot goes out, it cools off and shuts off the gas so the room doesn’t fill with gas. If the pilot goes out after lighting it and holding the pilot button for 30-60 seconds, then releasing the button, the thermocouple is normally the culprit. Usually, they’re universal, cheap and easily replaced - under ten bucks and the round trip to the store to get one will take longer than the actual replacement. ---
**Author:** ![Zsofia](https://avatars.discourse-cdn.com/v4/letter/z/7bcc69/32.png) [@Zsofia](https://boards.straightdope.com/u/Zsofia)\ **Post date:** [September 23, 2015, 7:04pm UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/10 "2015-09-23T19:04:36Z")
But so this is an autolight son of a bitch that has a ton of warnings about opening up the bottom - is that different to replace than a simpler water heater? ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [September 23, 2015, 7:13pm UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/11 "2015-09-23T19:13:11Z")
> [@Zsofia](#): > > But so this is an autolight son of a bitch that has a ton of warnings about opening up the bottom - is that different to replace than a simpler water heater? [Apparently it does not](http://enlightenme.com/water-heater-thermocouple/)have a thermocouple. > [@link](#): > > Many newer, energy efficient water heaters have electronic ignition instead of a standing pilot light and thermocouple. They contain solid state controls that only ignite the gas burners or pilot when the storage tank needs heat. Look for the copper tubing. If you don’t see it, your gas water heater has electronic ignition. That puts it out of my league. ---
**Author:** ![Dag\_Otto](https://avatars.discourse-cdn.com/v4/letter/d/439d5e/32.png) [@Dag\_Otto](https://boards.straightdope.com/u/Dag_Otto)\ **Post date:** [September 23, 2015, 7:35pm UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/12 "2015-09-23T19:35:22Z")
It’s possibly a dirty flame sensor. This is a device that senses that the electronic ignition has lit a pilot flame prior to turning on the gas for the main flame. You don’t want to turn the gas on full if there is no pilot to light it. The flame sensor can get dirty (IIRC, they are an optical sensor). High humidity levels associated with recent rain might cause condensation on the flame sensor so it doesn’t work properly. I think there are YouTube videos that show how to clean them. ---
**Author:** ![slash2k](https://avatars.discourse-cdn.com/v4/letter/s/439d5e/32.png) [@slash2k](https://boards.straightdope.com/u/slash2k)\ **Post date:** [September 23, 2015, 7:52pm UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/13 "2015-09-23T19:52:58Z")
Wind can extinguish a pilot light (when it’s in just the right quadrant at just the right speed, it creates a venturi effect and a draft in the vent pipe to blow out the flame). Replacing the vent cap might fix that. In your case, since it’s in a shed, maybe wind is causing a draft in the shed and blowing it out directly? or vegetation growth is changing the wind patterns just enough? You mention a correlation to rain events; do those match changes in weather patterns or wind direction? I can’t quite envision a way for rain inside the vent to knock out the pilot, but I suppose it’s possible depending on your install. Excessive humidity would be the next culprit to investigate. ---
**Author:** ![Quercus](https://avatars.discourse-cdn.com/v4/letter/q/7ab992/32.png) [@Quercus](https://boards.straightdope.com/u/Quercus)\ **Post date:** [September 23, 2015, 8:35pm UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/14 "2015-09-23T20:35:22Z")
> [@Quercus](#): > > If this was just installed a couple months ago, and you’ve had the problem since it was installed, I think it’s kind of up to the person who installed it to figure out what’s wrong. Whoops, I misread. Installed six years ago, I see. Sorry about that. So this heater has a pilot light that is always on (at least it’s supposed to be), but has it’s own built -in BBQ-clicker to re-light it? If so, then there probably is still a thermocouple, to make sure the gas to the pilot light gets shut off off if the pilot light goes out. And if the thermocouple is slowly failing, it might be hard to re-light the pilot (because you need to get the cranky thermocouple extra hot to keep the gas flowing to the pilot). The other option is, as mentioned, that something has changed to get wind coming in at a slightly different angle or something, but my guess is the thermocouple. ---
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [September 23, 2015, 10:31pm UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/15 "2015-09-23T22:31:15Z")
My SWAG would be the Thermocouple. It is getting old and becoming weak. The flame from the pilot heats the thermocouple. The heated thermocouple will then produce a small amount of electricity. This electricity is used to hold open the gas valve. If the thermocouple does not produce enough electricity the gas valve will close and the pilot and flame will go out. With a rain normally there is wind. More cold air entering the fire box can cool the thermocouple. If it is weak the voltage produced can drop below the point of keeping the gas valve open and flame out occurs. Changing the thermocouple on a newer water heater is a little more difficult. The fire box needs to be opened to replace the thermocouple. And after replacement the fire box has to be closed up properly and sealed. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [September 24, 2015, 1:31am UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/16 "2015-09-24T01:31:48Z")
I don’t know if out WH has a thermocouple or not, and I’m not going to violate the warranty by taking the lid off and looking. 🙂 I have had heavy winds blow out a pilot light at another house, but not repeatedly. ---
**Author:** ![usedtobe](https://avatars.discourse-cdn.com/v4/letter/u/ec9cab/32.png) [@usedtobe](https://boards.straightdope.com/u/usedtobe)\ **Post date:** [September 24, 2015, 8:09am UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/17 "2015-09-24T08:09:33Z")
After reading this, I still don’t know if there is a pilot light (OP referred to ‘re-lighting’) or electronic (which would explain the ‘auto’ comment). If this is in CA, it is probably an electronic - I know swimming pool heaters come with one or the other. If it is going to CA, it has to be electronic - CA Clean Air rules forbid pilot lights. ---
**Author:** ![Zsofia](https://avatars.discourse-cdn.com/v4/letter/z/7bcc69/32.png) [@Zsofia](https://boards.straightdope.com/u/Zsofia)\ **Post date:** [September 24, 2015, 1:32pm UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/18 "2015-09-24T13:32:21Z")
It does have a pilot light, but you don’t get in there yourself and relight it. You hold down the gas knob to “pilot” and click this little button a bunch, which you can theoretically see sparking through a tiny window but in real life totally cannot for a variety of reasons. ---
**Author:** ![Kimballkid](https://avatars.discourse-cdn.com/v4/letter/k/b5a626/32.png) [@Kimballkid](https://boards.straightdope.com/u/Kimballkid)\ **Post date:** [September 24, 2015, 3:44pm UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/19 "2015-09-24T15:44:02Z")
Can you get the brand name and product number off of it so we can tell exactly what we are looking at? ---
**Author:** ![Zsofia](https://avatars.discourse-cdn.com/v4/letter/z/7bcc69/32.png) [@Zsofia](https://boards.straightdope.com/u/Zsofia)\ **Post date:** [September 25, 2015, 8:43am UTC](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306/20 "2015-09-25T08:43:55Z")
Sorry, this is why it’s taking me a bit to get out in the back yard: [After setting rainfall record, wet morning Friday](http://www.wistv.com/story/30107763/flash-flood-warning-issued-for-richland-county) You’re gonna want to watch the video there of what the news called a “daring rescue” - I’m not sure what dictionary they were using, to me it’s more “no fear, ma’am, you’re safe now! Just go for a swim stage left with your precious offspring while I gaze in puzzlement at your car.” “Moron student risks life for YouTube” is also good. In other words, I ain’t getting a hot shower tomorrow. [Next page](https://boards.straightdope.com/t/why-does-my-water-heater-pilot-light-go-out-now/732306.md?page=2)