Water Heater Intermittent

PreCambrian · 04-15-2023, 11:04 AM

I have a problem that has stumped me. I have a Dometic WH-6GEA. The water heater when running on propane will shut off and then restart almost immediately. The problem has gotten worse (restarts more frequently now) to the point where it will only run twenty seconds before restarting. I thought that I had found the problem by bypassing the ECO switch but it turns out that the unit works fine when I have the access door open but when I close it the flame goes out and then the unit restarts again. I can only think of two possibilities. 1) When I close the door the flame sensor grounds to the door somehow. The wire between the DSI circuit board and the electrode does touch the door and I noticed that the insulation rating on the wire is only 600V while it probably takes 10,000 volts to spark the 1/8” gap on the electrode. The second and more likely cause is closing the door restricts the airflow to the burner. The burner has what I think is a good flame while the door is open (dark blue short flame with longer light blue flame). There is no way to adjust the flame that I can see. There is no air adjustment (opening is fixed). I’m at 5,000 feet at the moment in Monument Valley and that might affect the issue but the unit should operate at this altitude.

Does anyone have any suggestions? Does anyone know where I would take a pressure reading? There are a couple of plugs in the combination gas regulator/valve body that might be the proper place to take a reading but the service manual only says to check the pressure but it doesn’t say how.

**16ACE27** · 04-15-2023, 02:13 PM

Check your flame air ratio adjustment.

Could also be a dying ignitor/flame sensor or even a dying control board.

PreCambrian · 04-15-2023, 10:56 PM

Quote:

Originally Posted by 16ACE27

Check your flame air ratio adjustment.

Could also be a dying ignitor/flame sensor or even a dying control board.

There is no air fuel adjustment. The orifice is fixed and the air opening is fixed with no adjustment feature. Take a look at the photo. The flame looks nice and blue with no smoke or soot. I am not sure why the circuit board or igniter would only work with the door open, especially having problems within 30 seconds of shutting the door. The igniter is relatively cheap and easy however so I might grasp at straws and try replacing it.

Jimmers · 04-15-2023, 11:57 PM

Purchase a new ECO/T Stat kit.

PreCambrian · 04-16-2023, 03:34 AM

Quote:

Originally Posted by Jimmers

Purchase a new ECO/T Stat kit.

I bypassed both those switches using a jumper wire and the unit still drops the flame and restarts when I shut the access door.

Jimbo56 · 04-16-2023, 11:36 AM

Insect blockage in orifice intake?

PreCambrian · 04-16-2023, 01:38 PM

I don’t think so because the flame looks good with the door open and I don’t see anything (but I can’t see the entire burner tube). However I agree that is probably the best option to try next.

Has anyone cleaned their burner tube? Service manual says to run a flexible wire brush through it but doesn’t describe the procedure. There appears to be a “flame spreader” which blocks most of the outlet of the tube and the only way that I see to do a good job is to remove the tube which also involves removing the combination gas regulator/valve.

PreCambrian · 04-16-2023, 09:53 PM

Someone on a different forum (not RV Life) directed me to this post, https://www.irv2.com/forums/f54/dome...ut-595478.html

So others are having the same problem that I am having. Apparently a design issue. I will work on it. Looks like I might have to add intake air area near the burner.

My question now is, isn’t the above link an RV Life forum? I tried to comment, it asked me to login, and then it wanted me to establish a username. I figured since I logged in it would know my username. What is the difference in these forums and why can’t I use my existing username and password?

**16ACE27** · 04-16-2023, 10:00 PM

Quote:

Originally Posted by PreCambrian

Someone on a different forum (not RV Life) directed me to this post, https://www.irv2.com/forums/f54/dome...ut-595478.html

So others are having the same problem that I am having. Apparently a design issue. I will work on it. Looks like I might have to add intake air area near the burner.

My question now is, isn’t the above link an RV Life forum? I tried to comment, it asked me to login, and then it wanted me to establish a username. I figured since I logged in it would know my username. What is the difference in these forums and why can’t I use my existing username and password?

You should be able to log in using the same Username (email address) and password that you use on this Forum. Then you can create a Profile Name for that Forum which can be the same or different as the profile name you use here. Nomenclature may be confusing/inaccurate as we used to login using your profile name as the Username, but that was change to an email address a few years ago.

thorgem · 04-20-2023, 03:13 AM

I had the same problem, after installing a camco bug screen on the exhaust port. It restricted the exhaust air flow, which put out the flame, it then started up again,then went out . By opening the door it work fine. Now I only use the screen when I'm not using the motorhome.

thorgem · 04-20-2023, 03:28 AM

If you haven't installed a bug screen, then you may have a insect blockage in the burner exhaust tube.

Dan Thomas · 04-24-2023, 07:05 PM

Perfect timing, I was out prepping our 25M for an upcoming trip, fired up the hot water, Hmmm same symptoms, checked/cleaned the mix tube, exhaust stack, connections. Noticed when I closed the access panel it begin the die/re-ignite game. Rains came in so I buttoned up, read your post and the light bulb over head got really bright.. I'm going to try the diverter to see if it make s a difference. Thanks for posting.

PreCambrian · 04-24-2023, 09:46 PM

Quote:

Originally Posted by Dan Thomas

Perfect timing, I was out prepping our 25M for an upcoming trip, fired up the hot water, Hmmm same symptoms, checked/cleaned the mix tube, exhaust stack, connections. Noticed when I closed the access panel it begin the die/re-ignite game. Rains came in so I buttoned up, read your post and the light bulb over head got really bright.. I'm going to try the diverter to see if it make s a difference. Thanks for posting.

When you checked the mix tube did you remove the gas valve/mix tube (they are sold together and appear to be mounted to the same plate)? I don’t see a way to remove the mix tube without removing the gas valve.

After several communications with Dometic support, they actually responded to my emails and I am pleased with that, they say that I need to take it into a service facility in order to have it properly diagnosed. I am going to check the gas pressure and remove and check the mix tube before I take it into my RV dealer when I return from my trip. Dometic isn’t interested that I have more confidence in myself than I do in a technician that works at an RV dealer. I didn’t want to disassemble the unit while traveling without having all the potentially needed tools (and parts) and then have no hot water. For now my short term fix is to open the unit door when I need hot water.

I believe that it is a design issue but there is the possibility that the gas pressure is slightly high and the water heater may be more affected than the refrigerator, cooktop, or furnace. Or there is the possibility of a very minor obstruction (I read one post where just a few strands of spider webs caused a similar problem).

Jimbo56 · 04-25-2023, 02:54 AM

Quote:

Originally Posted by PreCambrian

When you checked the mix tube did you remove the gas valve/mix tube (they are sold together and appear to be mounted to the same plate)? I don’t see a way to remove the mix tube without removing the gas valve.

After several communications with Dometic support, they actually responded to my emails and I am pleased with that, they say that I need to take it into a service facility in order to have it properly diagnosed. I am going to check the gas pressure and remove and check the mix tube before I take it into my RV dealer when I return from my trip. Dometic isn’t interested that I have more confidence in myself than I do in a technician that works at an RV dealer. I didn’t want to disassemble the unit while traveling without having all the potentially needed tools (and parts) and then have no hot water. For now my short term fix is to open the unit door when I need hot water.

I believe that it is a design issue but there is the possibility that the gas pressure is slightly high and the water heater may be more affected than the refrigerator, cooktop, or furnace. Or there is the possibility of a very minor obstruction (I read one post where just a few strands of spider webs caused a similar problem).

Don’t you have an electric option?

PreCambrian · 04-25-2023, 03:50 AM

Quote:

Originally Posted by Jimbo56

Don’t you have an electric option?

Yes I can use electric but I have been in National Parks almost exclusively and only one had electricity. I did start the generator once and heated water and I might do it again if I really need to. I have had my RV for ten months and have 4.6 hours on the generator. I should run the generator at least an hour a month and using the water heater as a load makes sense.

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