need help troubleshooting water heater problem

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Old 08-25-14, 04:09 AM
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need help troubleshooting water heater problem

I have a 40 gallon Bradford White propane water heater(Model M440T6FCX) The problem I'm having is that it will turn on for about a minute, then the flames will lower drastically and stay at this lower level for a short while (5-10 mins at most) and then go out completely. When I come back and check it, the pilot light is also out. When the flames go low, I don't hear any sputtering, they're just low. A month ago, when this happened the low flames would stay on so the water would eventually heat up. But right now they're not staying on long enough to even warm the water.

If I turn the pilot light back on, and leave it that way (without trying to turn the water heater on) it seems to stay on normally.

I notice that although the water in the WH is cool, when I turn it on, it doesn't click (and go on) until the dial is halfway between warm and very hot. It seems like this should indicate that the water inside is already pretty warm, but it's not.

Could this be a control valve problem, or possibly a bad thermocouple?

And if I have to replace the control valve, are there generic brands that would work...or am I stuck with an expensive Bradford White valve?

Thanks for any suggestions... John
 
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Old 08-28-14, 04:38 AM
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My water heater is back to the previous mode where the burner flames start up normal, but then get real low. However, now they're staying on, so if I wait long enough I get hot water. I'd hate to buy the expensive gas valve when it's just a thermocouple problem, but how do I know?
 
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Old 08-28-14, 07:17 AM
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Sounds like its starving for air and the thermal sensor is tripping from overheating of the combustion chamber. But this is external to your unit maybe and has a button that needs to be reset..

Does your unit have a series # on it so I can look up the service manual?


The air intake can be clogged or there could be a blocked flue from say birds nest or baffle that is damaged...

Last a manometer should be used at the gas valve test port and a W.C. measurement should be taken...

I believe this is your service manual with the older style gas valve...?

http://www.bradfordwhite.com/sites/d...ure/44943C.pdf
 
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Old 08-28-14, 05:51 PM
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Hi Mike...thanks for the service manual link, that looks very useful.

Here's the serial #: CL8460865.

I'll check the flue, but even if the flue itself were blocked wouldn't enough air get in through the gap just above the top of the heater (below the "hat").

Where would the thermal sensor be located..."external to the heater", does that mean not attached in any way (other than a wire...which I don't see anywhere), or attached to the outside of the water heater?

John
 
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Old 08-28-14, 09:16 PM
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It would be starving for combustion air, that comes in at the bottom of the heater. The air space around the vent hood is to allow a neutral draft at the exit from the heater.
 
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Old 08-29-14, 06:47 PM
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I don't know why I thought air would intake through the exhaust flue, but I did imply that, didn't I. Looking at the bottom of the WH, there are a series of horizontal 1" slots in the inner wall, these must be the air vents. I can see eight or nine, and there's no sign of anything clogging them...and I stuck a wire through seven of them, didn't feel any obstruction.

I have a manometer around someplace...do you know what size fitting is on the gas valve?
 
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Old 08-29-14, 11:54 PM
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I don't know anything about your particular water heater, that's Lawrosa's area of expertise. Most combination gas controls have a 1/8 inch female pipe thread port for checking the gas pressure.
 
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Old 08-30-14, 06:36 AM
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Check your warranty status here please..

The serial # you gave is wrong it says...

Check Your Warranty | Bradford White Water Heaters. Built to be the best.
 
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Old 08-30-14, 07:29 PM
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Mike...I checked the warranty link you sent, my serial number worked but alas the warranty expired in Feb 2013. I've been checking for a price on the gas valve and Bradford White wants $181 for it. I found another place selling it for $101 (HVAC & Plumbing Supply - SupplyHouse.com - Formerly Pex Supply). I'm going to try to find a manometer I have (used it years ago with a gas space heater problem) and I suppose that's the next thing I should try.

This week the water heater is working a little better, the flames still drop to a low level but they stay on so eventually I get hot water.

Since no one has mentioned it, I'm guessing the thermocouple has nothing to do with the kind of problem(s) I've reported.
 
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Old 08-30-14, 08:05 PM
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IMO its over 6 yrs old.. Get a new unit for $364 what a paid a few months ago..

Get an AO smith would be my choice


You could change the valve and it can leak tomorrow..

Find your local Ferguson...

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Old 08-30-14, 08:51 PM
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I agree with Mike. Putting a new thermostatic gas valve on that tank is throwing good money after bad.
 
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