Water heater pilot went out-

[Kev Williams]

Woke up to barely warm hot water this morning. The pilot light on our barely 4 year old 40 Gal AOSmith water heater was out. The pilot re-lit easy enough, and the burner fired up like it should. And about 10 seconds after it fired, the 'howling' started, as usual... ever since I installed it, the thing howls every time the burner fires, I'm assuming something to do with the rush of hot air going up the flue and heat expansion causing some vibration. Anyway, all normal. I'm on the floor looking in the window and the flame is quite yellow, and for several minutes I could hear hissing, exactly like water on a hot skillet. My first thought was the tank is leaking from the inside- BUT, there's no trace of any water ever having been in the catch tray, no calcium tracking, no water marks on the heater. I figure if the tank WAS leaking from the inside, it wouldn't just leak while the burner was on, water pressure would keep pushing it out. Also, after about 5 minutes during the reheat the hissing stopped...

So my next guess is condensation within the burner is the source of the hissing water. And it makes sense I guess, the coldest it's been in the last 4 winters has been like 15°, and right now it's brutal cold outside, got down to like 1° overnight and most of yesterday it never got above 15°, so I'm guessing the extra-cold water coming into the water heater may have caused some condensation to form within the burner, and some of it dripped onto the pilot, snuffing it out...

I'm just wondering if the condensation theory sounds plausible, and if anyone else has had something like this happen? Not sure how to deal with this other than hope it warms up outside and the pilot stays lit!

At least this heater has one of those 'pilot-on' indicators, a blue light that blinks every 3 seconds as long as the pilot is lit, and the heater is in plain view, easy enough to check during the day-

[Lee Schierer]

The howling and vibration is likely caused by the water boiling under the accumulated calcium and other mineral deposits in the bottom of the tank. The pilot going out could be caused by back drafts if the roof shield isn't in place or back drafts in the stack due to a missing hood or hole in the flue. A weak thermocouple could also cause the pilot light to go out.

[Malcolm McLeod]

... looking in the window and the flame is quite yellow, ...

Flame color would lead me to believe your gas supply may be a bit sketchy. Might warrant a call to your utility.

As for condensation, water vapor and CO2 are primary byproducts of Nat Gas (mostly methane) combustion. If the flue is cold enough, the water vapor may condense prior to exiting the flue. Could this drip on the pilot??? I'll leave that to your eyes.

Or do you just have off spec gas supply and pilot blows out from turbulence of heat cycle cut-off?

******
ETA - Some further pondering: flame color may be poor fresh air flow :: not enough O2. I could only speculate as to cause. ...I've owned 10 or six water heaters; no howlers in the lot.

[Kev Williams]

After the burner was on awhile and the hissing stopped, the flame was mostly blue like it should be. Pretty sure the gas supply is fine. I have a wall mounted ventless 22,000 btu NG heater in my garage shop, connected to the same gas line, it's flame is always blue, as are all 5 burners on our GE gas range...

This was the first time a pilot has ever went out in this house that I can remember since 1969. Current Goodman furnace has a piezo igniter, as does the range, the water heater and the garage heater have pilots-

[Bruce Wrenn]

Water vapor can cause discolored pilot light. When we run humidifier in house, flames on gas stove turn kinda orange. You shouldn't have any condensation on center tube of WH, as it's in contact with the warmed water. Due to extreme cold, last of flue gasses, or air from inside the house rising thru vent pipe, could be condensing on vent pipe, running down inside center tube The incoming water contacts bottom of the tank, which could cause condensation. Have you contacted AO Smith about your problem?

[Tom M King]

Howling sounds like a check valve.

[Bill Dufour]

Your gas company should come out and check stuff for free.
Bill D

[Jim Koepke]

A weak thermocouple could also cause the pilot light to go out.

Another problem related to the thermocouple is the clamp that holds it in place. If the screw is loose the thermocouple will not generate current as well and may cause the safety shut off to close the gas line and kill the pilot.

Many years ago my gas water heater needed the screw holding the clamp for the thermocouple tightened every few years.

jtk

[Kev Williams]

2 mornings later-- I just washed off some operator panels I'm making which kicked on the water heater-

Flame has some yellow in it but it's not mostly yellow. Analyzed the stove flame, occasional small yellow flame tips occur pretty much always-

I specifically listened for any hissing, there was none whatsoever. Only hiss at all was the gas entering the burn chamber...

--and it howled, as usual! (I'll have to record it, it's very similar to the 'howl' of blowing across the opening of glass cider jug, just louder!) ;)

Just an anomaly it seems :)

[Kev Williams]

in case anyone cares, found the problem...

after 3 more pilot outages in the past 3 weeks, 2 of them lighting off burner gas in scary, loud fashion, last one earlier today, I thought about getting a tankless. Only problem with that, there's hardly any available without waiting 3-4 days!

So I go to light the pilot again, only this time it simply wouldn't light, just a faint wisp of flame occasionally. This went on (and off) for nearly 2 hours. Told the wife I suspected, HOPED, that the pilot tube was just dirty, but I didn't want to shut all the gas off in the house just to check the pilot tube.

Then it dawned on me... no thermocouple, no gas delivery unless I push the 'pilot' knob in ;)
Pilot tube seals with a ferrule fitting so no tape needed, so I grab a wrench and remove the tube from the Honeywell controller. No smells. Push the Pilot button, immediately got smells. Wiped the end of the tube off, put 'er up to my lips, and blew... Not a whole lot happened, but I didn't expect to blow much thru a .010" hole, so I tried some suction. At least when the suction grip quit I knew it wasn't totally plugged up. Gave it another push for good measure, and screwed the tube back in...

Much to my surprise, after 2 hours of nothing, I pushed the Pilot button, waited 5 seconds or so, and the pilot fired up first click of the piezo. And the pilot flame was noticeably bolder than before. It's actually quite visible thru the sight window, before I could hardly see it..

My theory (conjecture) is that the weak pilot flame was being pushed sideways under the shroud by the residual air in the burner chamber being moved around by the incoming NG- and the 'hidden' flame wouldn't light off the gas until the air finally got moved out of the way enough, and by then there was too MUCH gas, which just went BOOM, and blew out the burner AND the pilot flame...

After a few minutes I turned the knob to 'medium hot' and the burner simply lit with no drama whatsoever. Dirty pilot tube, nearly spent $1400 today for that!

A tankless is still in our future, this one still howls ;)

[Jim Koepke]

Great Kev, now some other folks may benefit from your experience.

jtk

[Thomas McCurnin]

I love my Noritz tankless. Its 20 years old and works like a champ. With the savings in gas, probably paid for itself a couple times over. You will have to de-scale it once a year or use a scaling filter and de-scale it less frequently but still every couple years.

[Keith Pitman]

Somewhat Unrelated to your issue, but in case it might help others, on our previous water heater, we frequently had “flame outs” when we had high winds here — not uncommon in the high mountains. Easy to restart, but tricky to coach the wife to do so when I was a thousand miles away. Apparently wind would blow down the flue and extinguished the pilot flame. New water heater has an electronic ignition and haven’t has an issue since.

[Bill George]

Most pilot problems come from insects and such building cobwebs inside the burner orifice area or line or just plain dirt.

I will never have a tankless water heater.... why the huge gas/electric line needed for one, the lime issue for us folks in hard water country.

When our gas bill for heating water is $20 per month, where is the savings?? It takes X Btu's to heat one gallon of water to X degrees regardless, our water heater is hi Eff 40 gallon and can store what little hot water we require at next to nothing cost. The tiny pilot helps keep that already heated water warm.
Retired family of 2 with lots of laundry and a daily dishwasher run.

If we paid $100's to heat water, sure... maybe.

[Jerome Stanek]

I put a circulating pump on my water heater and have pretty much instant hot at all the faucets. It does seem to save on the water bill as I used to have to wait 30 seconds for hot water in my bath and 45 in my wife's bath. gas usage has stayed about the same.

[Ole Anderson]

I put a circulating pump on my water heater and have pretty much instant hot at all the faucets. It does seem to save on the water bill as I used to have to wait 30 seconds for hot water in my bath and 45 in my wife's bath. gas usage has stayed about the same. Good idea for long runs. Usually combined with a timer to only recirc during times of need and you want to make sure to insulate the supply and return pipe or you will just be heating your stud cavities/joist spaces.

[Jerome Stanek]

Good idea for long runs. Usually combined with a timer to only recirc during times of need and you want to make sure to insulate the supply and return pipe or you will just be heating your stud cavities/joist spaces.

This is the one I got I did have it hooked up like they say but I ended up running a PEX return line with a check valve in because the way they have iy hooked up the cold water is warm until the pipes a fushed by running cold. That just defeats the saving water.

https://www.lowes.com/pd/Watts-HRWS-Universal-Steel-Water-Heater-Recirculating-Pump/3135231

[andy bessette]

Another problem related to the thermocouple is the clamp that holds it in place. If the screw is loose the thermocouple will not generate current as well and may cause the safety shut off to close the gas line and kill the pilot...


This is the most likely cause--insufficiently tightened thermocouple.