Gas-fired water heater pilot keeps going out.

Hap_Hazzard

I have a 10 year old natural gas-fired 40 gallon water heater that has worked fine for the last 10 years until about a week ago when the pilot went out. I re-lit it and it worked fine for a week, then last night it went out again. I came home tonight to find it out again and re-lit it, and I just went down and checked it and it was out again.



The pilot flame looks reasonably strong. It's not as big as the flame on my steam boiler, and there's no prominent yellow peak, but it looks stable. I don't see any way to adjust it anyway.



The thermocouple seems to work--I have to hold the gas button down for about a minute before the pilot stays lit, but once it heats up it stays lit.



There's no water leak. It's in a floor pan, so I'd be able to see water if it were leaking.



Something has definitely gone bad, but I don't know what to check, and I get the feeling that if I pull the burner assembly I won't even know what to look for, except maybe schmutz in the pilot orifice.

Pilot RE

re

In my experience, these symptoms are caused by either a bad thermocouple, or more often, by a small leak that opens when the tank is warm and drips into the combustion chamber. I would relight the tank and keep an eye on the combustion chamber for drips and sizzles.

Larry Weingarten

Agreed

Look for the drips and sizzles first.  If they don't happen because the tank is mostly up to temperature, the thermocouple is the first thing to check.  Make sure it is being heated to a dull red by the pilot and check to see the connection to the control is reasonably tight.  If those things don't work, replace the thermocouple.  If that still doesn't work, you're facing a new (expensive) control.... but controls rarely fail.  Also, if you can make it work, consider a new anode and relief valve for the tank to keep it working safely. 



Yours,  Larry

Hap_Hazzard

Drips and sizzles

I did hear a few sizzles shortly after the burner came on, but they stopped after the tank warmed up. I assumed it was just condensation since it only happened when the burner was on and the tank was cold. I really hope it's not leaking. I want to replace it with a tankless heater, but I'm not ready to do that yet.



How long do these things generally last? I replaced the anode about three years ago, and at that time a lot of the old one was still there, but it had broken off and fallen inside. It looked like a coral reef in there. Calcium crystals everywhere. We have pretty hard water.



I noticed that the thermocouple doesn't glow like the one in my boiler, but I assumed it was okay since it heated up in under a minute. If anything I thought the flame just wasn't hot enough.



So I guess I'll pick up a thermocouple and pull the burner, clean out the orifice, check for blockage in the line, replace the thermocouple and look for hard water deposits on the burner assembly. If it's just condensation I'm hearing, that won't leave any, but the tank water definitely will.



Thanks for the suggestions. I'll let you know what I find.

Pilot RE

Another thing to try

You can also try setting the tank to a higher temperature and/or draining some sediment to see if you can induce a leak or a shut down. Some condensation at start up is normal.



I have about 70 water heaters with six year warranties and they last about ten years on average.

Hap_Hazzard

Update

I haven't gotten around to getting a thermocouple yet, so I haven't taken the burner out, but the pilot hasn't gone out since I made the first post.



It must have figured out I had some wallies on the case.



I'll take a look at it this weekend one way or another.

Hap_Hazzard

Reupdate

Saturday I took the burner assembly out and inspected it. There were some deposits that could have been hard water residue, but were more likely sulfates. No sign of rust.



I got a new "universal" thermocouple, but when I got a look at the original one it looked different. Since it was apparently working I decided to leave it, but I'm going to try to get an exact replacement to have on hand.



The significant finding was that the orifice looked obstructed. When I held it up to the light the hole didn't quite look round. It had a "1" on one side of the orifice and a "4" on the other, which I took to mean 14 thousandths (.014"), and it looked about that size, so I got a piece of .014" wire (a guitar string) and pushed it through the hole to clear it out, then blew it off with compressed air and put it back together.



When I got it lit again, the flame looked a lot bigger--still no yellow peak, but almost twice the size, and it hasn't gone out once since I lit it.



So I'm going to call it fixed for now, but start getting ready to replace it with a tankless heater.

Hap_Hazzard

It's at it again. The pilot went out twice last week and several more times this week. Yesterday I actually caught it in the act.

I was getting my steam boiler ready to fire up and had just checked the pilot on the water heater, which had just finished heating and was making typical cooling noises. Suddenly I heard what sounded to me like a switch or relay of some kind. I checked the pilot again and found it was out. It seems like the control unit senses a drop in voltage from the thermocouple as it gets cooler and turns off the pilot.

The thermocouple nut is left-handed, so I can't use a generic thermocouple, so I wrote down the model number (Whirlpool FG1F4040S3NOV) so I could search for a replacement part. What I found was a little surprising.

Apparently I've been lucky. My water heater is a "Flame Lock" model. These water heaters have a very bad history when it comes to pilot failure. So many customers repeatedly replaced thermocouples and/or control units that there was a class-action suit. Since I never had a problem until a couple of months ago, I missed out on the settlement, but they made an improved control unit and burner assemblies for all the models in that series. It's too late to get them replaced free, but at least they're still available from Lowes, so I ordered a control unit and burner assembly. It should be here sometime this week.

Steam_Starter

FVIR- Ugh.

I was having the same exact problem. PL would go out when it wanted to (but usually before the first AM shower.) I pulled the burner assembly and vacuumed the inside of the burner box. Paid close attention to the FVIR stamped intake screen in the bottom of the unit. Blew it out and it was full of dust and cat dander.) Gave a good vacuum under and around the unit and it has been working fine ever since (about 3 months ago.)

Sometimes you need to reverse flow the shop vac and blow into the screen then vacuum underneath. The intakes are way too small and any dust that accumulates on the screen starves the unit and POOF. Pilot goes out.

Good luck with it.

Tim McElwain

I have written a complete service manual on FVIR Water Heaters. It is available for sale by contacting me at gastc@cox.net.

Tim McElwain

The problem with the Whirlpool water heater actually made by A.O. Smith I believe was the left hand thermocouple. The company that made them quit making them. There is a replacement program in place for a complete new assembly for shipping costs only $8.00. Call 1-800-999-9515 or www.flamelocksupport.com with an exact Model number and complete serial number and I think you can still get a complete burner replacement with a right hand thread thermocouple and an adapter so it will fit into the water heater control.

Abracadabra

@Tim McElwain‌ are you sure about that www.flamelocksupport.com website? Looks like some kind of spam site.

Robert O'Connor_12

●Test thermocouple & change if weak
●Vacuum screen
●Change burner assemblyhttps://us.v-cdn.net/5021738/uploads/editor/fy/39sg5gn23jby.jpg

●Buy Tim's book

If that's not it, then it's the gas valve.
In my opinion, the heater is of sufficient age to warrant replacement.
good luck!

icesailor

"" I have a 10 year old natural gas-fired 40 gallon water heater that has worked fine for the last 10 years until about a week ago when the pilot went out. ""

If the water heater is 10 years old (4 years out of warranty), they might not cover a replacement under warranty. And unless you are a professional contractor in business, they might not sell you a new part, let alone give it to you.

Myself, as a professional, I had more than one occasion where a manufacturer refused to provide me with replacement equipment for a re-called product that I regularly installed and serviced. They said that the customer had to get someone who was in the business of regularly installing that product. Like myself. Didn't matter. Even when I said that if the house burned down because of their defect, that I wanted to repair, I would be first in line to see the customers lawyer about their company's refusal to honor their safety warranty the morning after the fire. Didn't matter. Even if no one wanted to do it that they approved. Still didn't happen.

WHy there is still so much Plex Vent still out there. Wait until PVC gets recalled.

Who should care?

Tim McElwain

I went to that web site and it looks like they shut down the rebate on those water heater burners. I need to call the 800 number to make sure. I guess now you have to pay for the burner and the shipping.

Hap_Hazzard

The replacement burners and control units are available from Lowes. I recommend replacing them together so you get a right handed thermocouple and a right-handed tapping on the gas valve and a thermal switch and a place to plug it in.

pattersonheating

Out of 27 pilot light going out service calls on hot water heaters last year, 24 of them were caused by the (FVIR) air inlet screen on the hot water heater being clogged with dust and dirt. It's clogging mimics a failing thermo couple quite well. Open up the burner compartment inspection sight glass and use air nozzle to blow out screen and problem solved. Around 2000 California started requiring all hot water heater to have the screens so that the flame wouldn't be able to escape combustion area and cause fires. With the California market being so large, most water heater manufactures found it easier to install it on all units. My water heater call outs went up about 300% about 5 years after that. If home owners would keep water heater floor areas clean and lint free, my call outs would probably end.

icesailor

And be more judicious about keeping lint filters clean on their dryers.