Fluctuating water heater flame

[davidlu54]

I have a Sears water heater with a manufacturing date of 1998. Over the past year, we have been having problem with the pilot light going out. What I then noticed is that after relighting the pilot light, the burner flame first comes on nicely, but then after a few minutes, the flame starts to fluctuate continuously as if it ready to go out. The unstable flame makes a very scary sound like "whomf ... whomf ... whomf ..." once per second. I am deathly afraid that the flame may cause an explosion. When the flame does go out, it sometimes "knocks out" the pilot light.

Someone else posted a similar problem in which they describe that "for no apparent reason the flame will dim, then come back on again, then a few seconds later it dims again. This will continue until I turn it off. Sometimes when it comes back it comes back with a flash. Does this seem like a problem with the gas valve, or the thermocouple, or what? Can someone give me some guidance with this so I can troubleshoot it." LINK
http://www.************.com/forum/w...s-back-dims-comes-back-etc.html#ixzz2mICfb5vc

Is this a gas pressure problem or something else?

Would replacing the water heater solve the problem?

We did remodel the house 4 years ago in which we added two gas fire places and another water heater. But the flame problem appears to be present even when those appliances are not on.

 

[Reach4]

Would replacing the water heater solve the problem?

Probably. A new heater would have new everything. If you could correlate your problems with wind, or the if the other gas devices you mentioned showed similar flame behavior, that would show some very unusual problem outside of the water heater. Those are unlikely.

Your water heater is about 15 years old, so investing troubleshooting and repair effort is probably not worthwhile.

Out of curiosity, you could pull the the old anode rod for inspection before discarding. It would probably require an impact wrench with a 1-1/16 socket. Few people do this. If you happened to have access to the impact wrench and socket, you might find it of interest.

If you think you might want to replace the new anode some day, you might want to pull the anode from the new water heater, and apply teflon tape. Screw it back in with much less force than you had to use to remove it. Few people do this. I have not done this, although I did install a powered anode in my water heater.

 

[Sponsor]

 

[hj]

Without testing it, there is no way to give an answer. If it is a gas pressure problem, a new heater would have the same problem. One remote possibility would be if the gas line goes underground and has rusted out so water is in the pipe. That would cause the sound as the gas forces its way though the water in "bursts".

 

[DonL]

The best way to test it would be to turn it off and use the other appliances on the gas line and see if they have problems.

That heater is old enough that it could have Gas Valve problems. Would not hurt to replace it.

I would not use it until repaired.


Good Luck

 

[Dj2]

All good answers.

If you don't report gas supply problems in the other appliances, only at this water heater, then replace it. I wouldn't bother trying to fix it. After 15 years you got your money's worth out of it.

 

[DonL]

I agree it is not worth fixing.

But it may be hard to find a new one that will last as long.


New is not always better...

 

[MACPLUMB]

"if" you have a old "steel" underground gas pipe I have seen when water leaks into the pipe you have the pressure changes you posted !

Check with your gas supplier otherwise it is time to get a new water heater
PHD in Water Heaterolgy

 

[davidlu54]

Being an amateur, I would like to thank everyone for all the thoughtful replies in less than 12 hours! In response to your advices

1. DonL and dj2 - I have already turned off the water heater until I get a new one. This is what my wife recommended in the first place.
2. Reach4 - are you suggesting that the anode rod is part of the problem? When the "master plumber" installed the water heater 15 years ago, he left out the anode. It was at the end of the installation that he tried to insert the anode, but it was too long to insert from the top due to the low furnace room ceiling. The plumber didn't want to take everything apart, and told me that the anode was not really necessary. I wrote a complaint to Sears, but never heard back from them.
3. hj and MACPLUMB 777 - water in the gas line is a very interesting possibility! Do I call our gas supplier and how do they check for water in the pipe? Should I contact them before replacing the water heater?
4. DonL - with an old gas valve, I guess it is possible that the thermopile is weak and not putting out enough millivolts to keep the main gas valve open ???

One more thing, when cleaning the venting pipe, we noticed that there is a lot of back draft, can this be a problem also?

Thank you again for all your help. I will keep you updated on the progress.

 

[Jadnashua]

FWIW, the anode rods are installed at the factory, and while there may be a good reason to remove one during installation, it escapes me.

A sacrificial anode is there for a chemical/physics reason...it gets 'attacked' preferentially verses the tank. Boats, bridges in water, towers, buoys, etc. all have them to keep them from rusting out, and they need to be replaced periodically as they literally get eaten up, IF you want max life. It all has to do with using a metal that is more reactive than the metal you want to preserve.

 

[Reach4]

FWIW, the anode rods are installed at the factory, and while there may be a good reason to remove one during installation, it escapes me.

One reason would be to put teflon tape on the threads and to put that same rod back using a lower torque -- maybe 15 or 20 ft-lb. This would be to facilitate easier removal and replacement after several years.

An alternative would be to replace the rod with a less active rod which reacts less with the sulfur but does not protect as well, or to use a powered anode, which does not react with the sulfur in the water and does the better protection.

These things are seldom done to a new heater. Some people will replace an anode rod before a tank leaks, but many more people do not do so.

 

[Master Plumber Mark]

please just change the 1998 water heater...
Install the new heater in a catch pan
and pipe it to your drain....... done and over with....

PLEASE...lets put this thread out of its misery
before everyone debates how much
teflon tape shoud go on the mag rod threads.....

 

[Reach4]

... before everyone debates how much
teflon tape shoud go on the mag rod threads.....

Hey good point! I am glad you brought that up. You still need a good electrical connection on that fitting, so don't overdo the teflon tape.

Seriously, I know that very few people pull anode rods if there is not a sulfur smell. It is almost surprising that they still make the rods replaceable.

 

[hj]

I have known many people, including plumbers, who have replaced a water heater to get rid of a problem only to find they still had it afterwards, because they DID NOT check for the 'real' problem first. One plumber returned the new water heater because it was "defective and would not heat the water". He got very upset when I told him that he probably had an underfloor hot water leak which was draining the tank as fast as the water was heating. They would not give him credit for the tank until it was returned to the manufacturer and verified that it was defective. Of course that did not happen and the heater sat at the wholesaler for months until he came back and picked it up.