water heater burner flame dims, comes back, dims ,comes back, etc...


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Old 07-24-10, 05:51 PM
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water heater burner flame dims, comes back, dims ,comes back, etc...

I have a Bradford 40 gal propane water heater, about 4-5 years old. So far this is an intermittent problem, occuring occasionally. The burner will come on, working normally and heating the water. Then 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.
 
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Old 07-24-10, 08:28 PM
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What you are describing is probably an intermittent interruption of the proper gas pressure. Lots of things could cause that.

Is your tank nearly empty or just recently filled?
 
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Old 07-24-10, 10:40 PM
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The tank was filled about a month ago.
 
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Old 07-25-10, 06:50 AM
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Do you have other propane appliances? Are they experiencing similar problems when the water heater has the problem?

If the tank was over filled, you might be sucking up some liquid propane that doesn't boil into a gas, causing that kind of problem. Or it might be a bad regulator not providing a constant pressure. Either of these problems would cause similar symptoms if other appliances were operating at the same time.
 
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Old 07-25-10, 03:19 PM
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The water heater is the only appliance using propane. And yesterday I lit the water heater and tried again. It worked for about three minutes and then shut off. A few minutes later I tried it again and this time it worked normally, heating the water as it should. So it seems to have two ways that it fails: 1) it works for a while then shuts off, or 2) it works, then the burner dims(or goes out and immediately comes back on) and then comes back full force....and does this a number of times until it shuts off or I shut it off.

I may have a gas pressure gauge but it's not an inline type. If I can set it up on a tee, inline, would that give me an accurate reading of the pressure?
 
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Old 07-26-10, 12:48 PM
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Originally Posted by jbclem View Post

I may have a gas pressure gauge but it's not an inline type. If I can set it up on a tee, inline, would that give me an accurate reading of the pressure?


Yes. It needs to be able to read inches of water column or about a 1/2 PSI with reasonable accuracy.
 
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Old 08-07-10, 11:10 PM
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Hello again, my water heater has been working fine until today, so I didn't see any point in checking the gas pressure. And the problem started up again today, so I pulled out my manometer and discovered that I had the wrong fittings/adapters to hook it up to the flex pipe. Then I took a closer look at the problem and here's what I noticed:

The pilot light looks pretty good, blue flame with a yellow/white section (inside the blue flame) in the upper center part of the flame. When I turn on the burner, it lights and everything works normally for a minute. Then the pilot light diminishes in size, but the burner flame stays normal. When the pilot light gets very small, almost not there, the burner flame gets smaller. Then the pilot light will get larger, and so will the burner flame. This fluctuation occurs a few times, then the pilot light will get real small and seems to disappear...then the burner flame goes out. At that point I turn the valve control back to PILOT(from ON) and the pilot light seems to come back to normal size.

I tried leaving the pilot light on for 30 minutes, then turned the burner ON again. The fluctuation procedure repeated itself. I tried leaving the pilot light on for another period, and tried again. After 3 or 4 of these attempts, the water heater started working normally again.

I'm wondering if the fact that the pilot light is first dimming without the burner dimming, would this eliminate low gas pressure as the cause? Since the pilot light always comes back on full when I turn the valve control back to PILOT, this doesn't feel like a clog or a pressure problem? But I'm no expert, so I hope someone is watching and will comment on this.

John
 
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Old 08-08-10, 09:58 PM
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You still need to measure the gas pressure while this is happening to determine whether gas pressure is the problem. It's the most likely cause of the problem, m and you start troubleshooting by checking out the most likely problems, not long shots.
 
 

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