Hot Water Heater - Electric and LP not working

[J_PNW]

Hello All,

First post. New to the forum, and to the 5th wheel life. Not sure if this is the right spot for this post. So the rig is a

2017 Forest River Chapparal 5th wheel.

Having issues with the hot water, its cold!

This all worked 6 months ago when I purchased the 5th wheel. Then it sat at the inlaws while I worked on a few things to get it to its current location, where it is now.

Also, a bit of extra context because I am not 100% sure if they are related to the hot water issue or not. (maybe something to do with the 12v system overall idk) The furnace is also not igniting and the 'RV Propane Gas Detector' which is hardwired into the wall, isn't working. But I am not focusing on that presently. Just want to present as much, maybe relevant, info as I can.

The water tank model is GC10A-4E. 10 gallon. LP and electric modes both don't work.

I believe I have narrowed the issue down to the curcuit board, but I am far from certain. Would appreciate a second opinion before purchasing anything.

I've purchased a new 12v deep cycle marine/rv battery already.

When I flip the gas hot water switch, there is LP coming out but no spark. The 'FTL' light comes on after 3 attempts. No ticking noise. Just a single click from what I assume is the gas valve.

I have confirmed LP is coming out via sound, smell, and manually lighting the fuel. It goes back out after manually lighting.

Stove top propane also works, confirming fuel in the lines.

I have checked all breakers and fuses.

I have checked that proper voltage is coming into the control board. All wires that should, have voltage. Thermal cut-off is functioning (confirmed by voltage and a bypass test). Voltage remains good before and after thermostat and eco switch. I can hear a click of the gas valve. I smell and hear the gas.

I DO NOT get any voltage reading on the connection for the spark probe. I understand that its supposed to be a high voltage but for just a split moment. Possible I am just not catching the reading?

I took the spark probe out, cleaned it up and confirmed it was gapped correctly. Tried it again, no spark.

So for the LP side, all the troubleshooting led me to gas present but no spark.



On the electric side, if I switch the electric hot water switch on, it lights up but nothing happens. I've waited a few hours to check if there any temperature difference, there isn't. I have also messed with the water bypass valve to make sure I didn't mess that setting up and think the water heater wasn't working, when it was. I can confirm that it is not heating up water.

I checked the voltage on the remote switch to control board wire, good. Voltage on yellow wire to relay, good. I could also hear a click noise when testing the yellow wire to relay with the multimeter.

I checked the electric hot water heating element for continuity. 11 ohms, good.

I wired the heating element back up, connected shore power, and very carefully tested the element for voltage... nothing.

So if I understand correctly, continuity shows that the heating element itself is good. But it is not getting the voltage to operate. But the voltage does reach the yellow wire that runs to the relay.. so that has me confused.



So at this point I am thinking circuit board. I will purchase a new spark probe while I am at it, just in case.

What do you think? Am I on the right track? New circuit board? Or maybe something else to look into first.



If yes on the circuit board, any experience with Dinosoaur electronics UIB 64 as a replacement instead of the dometic OEM part? I saw some good reviews on it.

Thanks for any help and insight!

 

[IPcamper]

I recently had to replace the circuit board on our Dometic water heater. Here is somethings for you to check.

On the circuit board there is a four pin connection and a six pin connection below it.



1 . Check for 12V on the White line on the four pin connector. This should have power when the switch for the electric power is on.



2. Check for 12V on the Orange line on the four pin connector. This should have power when the switch for the Gas switch is on.



3. If there is 12V on either of those lines, then there should be 12V on the brown line at the four pin connector. This is the sense line and runs to the thermostat and back to the circuit board on the six pin connector.
If there is no power on the brown line, check the 2A fuse on the circuit board, replace if bad and test again.
If there is still no power on the 12V line at the 4 pin connector, then the circuit board is most likely bad.


4. If there is 12V power on the brown wire, then test for 12V where the brown wire goes back to the circuit board.

If this point has no power, test the thermostat for continuity, and test the thermal fuse for continuity.



If you have NO power on the brown line going back to the board, nothing will turn on.

If you have power on the brown line and still nothing turns on, then the circuit board is bad.



You can test the 120V element by bypassing the circuit board. To do this disconnect the white wire at the four pin connector and jump that to the yellow wire that leads to the relay. With the Electric switch turn on, and 12V on the white line, the relay should activate and turn the 120V heating element on.


On a two week trip to Texas last month, our water heater died after the first night. I found that the circuit board was bad. I rig up a bypass circuit by piecing together some wire and a fuse to give me a bypass of ....


white wire ---> 2A fuse ---> thermostat ----> thermal fuse ----> 120V relay.


This allowed our water heat to turn on by the Electric switch and for the thermostat to turn it off at 140F. I ordered a new control board on Amazon and had it delivered to our home and installed after the trip.



Good luck with it.

 

[J_PNW]

Thanks for the response! Question about this

I rig up a bypass circuit by piecing together some wire and a fuse to give me a bypass of ....


white wire ---> 2A fuse ---> thermostat ----> thermal fuse ----> 120V relay.


This allowed our water heat to turn on by the Electric switch and for the thermostat to turn it off at 140F.


Good luck with it.

Could you go into a little bit more detail on how this works? How do I wire directly to the 2A fuse?

 

[Chaps2018]

I understand you verified the breaker, can you confirm 120v available? (Electric side operation)

Is the DSI light on? (When Gas side fails to spark)

Dinosaur board is the best solution if that’s the problem.

 

[Mr. Dan]

120v at the fridge outlet? (Electric side operation)

Dinosaur board is the best solution if that’s the problem.

I thought we were talking about a water heater, not a refrigerator?

 

[Chaps2018]

I thought we were talking about a water heater, not a refrigerator?

DOH! My mistake, corrected in the above post—thanks for the quick eye!

 

[IPcamper]

J_PNW , I bypassed the control board for my water heater but using a short bit wire to connect to the white wire at the four pin connector ( I twisted some of the bare wire and inserted into the connector where the pin would go, wrapped it with electric tape to keep it there. ) I put a small spade connector on the other end and inserted one of the contacts of the 2A fuse to that. I then used a short piece of wire with two spade connectors, one connected to the 2A fuse and then to the thermostat. After the thermostat, I used another piece of wire with two spade connectors to connect to the thermal use on one end, and the relay on the other end. It connects to where the yellow wire would connect to the relay. a more accurate description would be...
white wire ----> 2A fuse ----> thermostat ---> thermal fuse ----> relay ( at yellow wire connection )


I have attached a photo of when I was working out how to do this ( the thermal fuse is not included in this photo.

 

[IPcamper]

For a little more information, the thermostat is a temperature sensitive switch that opens ( turns off ) at 140F, it is rated for 125V, 15A. The thermal fuse is set at 98C ( 208F) 125V, 15A. the power going through them is only 12V, less than 2A. This bypass circuit is way below the tolerance of the components.
While this will work, I replaced the control board as soon as I could, since I prefer to run the heater on gas when possible.

 

[IPcamper]

Here is a photo of the 2 A fuse I used. I keep the wires in my tool box just in case I need it again.