# Hot water heater won't stay lit



## Cheryl (Sep 27, 2005)

I have been experiencing problems with the hot water tank in my RV for several months now and would appreciate any advice you can give me.  The RV is parked permanent and I don't have a vehicle to pull it into a service centre and the mobile RV repairman wants two arms and a leg to come out to look at it.  The problem started with the heater not always igniting after flicking the ignition switch inside the trailer, which incidentally always glowed red, even after the unit ignited and stayed lit.  Eventually I could get it to stay lit by trying several times in a row (turning off the switch, waiting a few minutes and then flicking the switch again).  It got to the point where nothing at all would happen - wouldn't even hear a click or anything when I turned the switch on.  I replaced the thermostat and a couple of other parts that came in a kit with the thermostat (sorry can't remember the name - two circular spring loaded things that the thermostat and another wire connects to).  It did light and stay lit a couple of times thereafter but still wasn't consistent in operation.  Within a few weeks it got to the point that the light wouldn't glow red at all when I flicked the ignition switch but the pilot would light and then promptly shut itself off again.  The light glowed once thereafter but hasn't ever since.  It now consistently lights when I flick the switch and then turns itself off although the light never glows red now.  I've been told it could be the circuit board or the regulator.  I'm wondering if it might be a wiring problem also.  Thank you in advance for any help/advice you can give me in this regard - I'm desperate!


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## Kirk (Sep 27, 2005)

Hot water heater won't stay lit

There are several possible things that could cause your problem, but I wonder how much you will really save by just changing parts? You need to do some actual trouble shooting rather than just throwing parts at the unit.

 The way that the light should work is that it should come on briefly and then go out once the heat sensor detects a flame. With an electronic ignition water heater there is no pilot at all. The ignitor lights the burner and will continue to spark until the flame sensor detects heat from the flame. If it does not detect any heat, either because the flame did not light, or because the heat sensor has failed, then it will turn off the gas and the ignitor will stop sparking. The red light should come back on, if that is working properly. The most common cause of the failure to detect burner ignition is the heat sensor, which is a part of the ignitor assembly on most modern water heaters. Since you do not appear to be getting the proper indicator lights, as well as failure to work, it is quite possible that the igniter circuit board has failed. 

To give more specific information about the water heater it would be helpful to know what make and model of water heater you have. While all of them do work in a similar manner, they are not exactly the same. There are two common makes, Atwood and Suburban. The two are not laid out the same nor are the different components located in the same position.


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## Cheryl (Sep 28, 2005)

Hot water heater won't stay lit

Thanks Kirk - very informative!  I have an Atwood heater.  Is the heat sensor the same as the T-Stat or what I'm calling the thermostat?  It's a wire covered in a plastic tube?  Unfortunately I don't have manual with me right now (forgot it at the RV the last time I was out) so I can't look it up.  I am a bit hesitant to just go out and buy the new circuit board as the price here is astronomical ($185 Canadian).  I did see a reference to Dinosaur replacement parts in one of the postings here - I'll have to do the math to see if it'll save me any money once I pay the exchange and duty and perhaps check a few other Parts stores.  Again I thank you!


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## Kirk (Sep 28, 2005)

Hot water heater won't stay lit

On your Atwood water heater, there is a black rubber cover over two devices, the left labeled ECO and the right labeled Thermostat. The ECO is the over temperature device and the one to the right is the thermostat that controls the temperature under normal operating conditions. Both of those are under the rubber insulation pad and have "spade" connectors that extend through the rubber. The "wire covered in a plastic tube" is a fuse type device that should be a direct short if in good condition. The flame would never light if the fuse were open, or defective. When operation normally, the power to the gas valve passes through the ECO and if the water temperature should get too high it will open to shut off the gas supply. The leads to the ECO are red and it does not matter which wire goes to each side of it. The thermostat has brown wires to it, with one coming directly from the circuit board, and the other connects to the "wire covered in a plastic tube" device and the to the other brown wire that supplies power to the gas control valve for the burner. 

I do not think that any part of that circuit is the problem. It sounds to me as though the problem is either in the igniter or the circuit board. There is a single wire that comes from a round plug on the lower part of the ignitor board that goes to the ignitor. That lead provides the power to the ignitor to supply the spark to ignite the propane, and it also the returns a very small voltage back to the circuit board when the probe heats up from the flame of the propane burner. The circuit board first sends a voltage out on that lead, then checks it for an indication of a flame. If none is detected it will send a voltage to spark again. It does that three times and if no flame is detected, it then should turn on the red light to indicate that the water heater has gone into lock-out. It must then be turned off to reset it, in order to try again. 

You can test for a propane supply by having someone assist you and you use one of the long butane lighters for lighting a propane barbeque to light it. Just light the flame of the lighter with it in the area of the ignitor and if gas is supplied when your assistant turns the water heater on, the lighter should ignite it. If the flame lights and the unit still does not stay lit, the problem is either the sensing ability of the igniter or the circuit board. I would replace the ignitor first as they cost less than $50 while the circuit board is much more. If I were to change a circuit board, I would use the one from Dinasour.


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## Cheryl (Sep 30, 2005)

Hot water heater won't stay lit

Fabulous Kirk  :approve:  - thank you so much - you're reply is very informative.  I had also emailed Atwood and they were kind enough to call me to discuss and they said exactly the same thing you did.  I will test with a new igniter and hope that fixes the problem.  I really appreciate the time you've taken to provide me with so much detail - it is very helpful indeed.  

Now that I've got the problem, with the TV, the stereo and carpenter ants solved all I have outstanding are the odor in the toilet, the wasps and the water pump!  Luckily I have a friend who is a motor rewinder so am hoping he can help with that one and the other two should be easy enough to solve - perhaps next summer will be more enjoyable.  I'm beginning to wonder why I upgraded from my 1979 Travelaire this year!  Have a great day/weekend and thanks again.  :laugh:


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