Hot water heater won’t shut off...

ArmyAV8R · 12-19-2018, 03:21 AM

2010 Flagstaff in new condition (stored in climate controlled shop since new; used 5 times). Everything works like new...except hot water heater on propane side. It ignites perfectly; clean blue flame...but it won’t shut off. I’ve replace the ECO/TSTAT 12V under black cover, to no improvement. Switching to electric, works and cycles on/off just fine. The only other thing I think it could be is circuit board...? But wouldn’t that cause it to not work at all?
Is there maybe a solenoid for pressure or the like that may have failed?

**Bama Rambler** · 12-19-2018, 09:11 AM

Are you saying that it trips the hi limit each time you fire it up?

The hi limit (Eco)/t-stat kills power to the control board whenever it opens. There's really no way for it to continue to fire unless the hi-limit/tstat is bypassed or the gas valve is leaking through. If the gas valve were leaking, you'd smell gas all the time and you'd get a heck of a backfire whenever it lit.

**Flybob** · 12-19-2018, 09:30 AM

There essentially two sets of controls on the circuit board so the temp sensing on the propane could be bad.

5picker · 12-19-2018, 09:59 AM

Does pulling the wire off the Eco/tstat stop the flame?

ArmyAV8R · 12-19-2018, 10:32 AM

Thank you all.
There is no tripping of anything. The flame is ignited perfectly, burns cleanly, no smell of propane and no back flame.
I have no pulled any of the 12V thermostat wires while the flame is burning to see if it goes out, but I will this afternoon. 5Picker, what will that tell me? What actions can I take?
As to the circuit board, I presuming that I need to replace it?
I’d imagine that’d be enjoyable.

5picker · 12-19-2018, 10:58 AM

Quote:

Originally Posted by ArmyAV8R

Thank you all.
There is no tripping of anything. The flame is ignited perfectly, burns cleanly, no smell of propane and no back flame.
I have no pulled any of the 12V thermostat wires while the flame is burning to see if it goes out, but I will this afternoon. 5Picker, what will that tell me? What actions can I take?
As to the circuit board, I presuming that I need to replace it?
I’d imagine that’d be enjoyable.

It will essentially do the same as the 'stat opening or the high limit opening.

I know you said you replaced it but just wanted to be sure that feed to the board was a wide open circuit by pulling the wire.

I suspect the control board.
If so... check out the Dinosaur Electronics boards. Much better quality.

Replacing it isn't difficult at all.
They are often times double stick taped to the back side of the water heater and often fall off and are laying on the floor.

Dinosaur Electronics

ArmyAV8R · 12-19-2018, 11:21 AM

5Picker, thank you. So if I pull either wire from the right hand 12V propane side and the flame goes out, it’s likely the board.
So then I’d pull the heater out and be able to reach the board on the tank...?

5picker · 12-19-2018, 11:29 AM

Quote:

Originally Posted by ArmyAV8R

5Picker, thank you. So if I pull either wire from the right hand 12V propane side and the flame goes out, it’s likely the board.
So then I’d pull the heater out and be able to reach the board on the tank...?

If you pull a wire off and the flame goes out it is probably NOT the board.
By pulling the wire you are effectively recreating a high limit situation or an up to temperature situation. That would mean BOTH high limit/'stat units are bad. (the original and the replacement) Not likely but never say never.

No, you won't pull the water heater out.
You'll go inside the camper to behind where the water heater is located and access it from there. You may have to remove a false panel, a drawer or something to get access as they are not always wide open to the interior.

You are going to need to get familiar with that area anyway in case you ever decide to bypass the water heater plumbing for winterizing/cleaning. Most (not all) bypass valves are located behind the water heater.

Here is a suburban 12v schematic for the water heater.
They really are pretty simple.

It is a Suburban, correct?

ArmyAV8R · 12-19-2018, 11:46 AM

Yes sir, Suburban SW6 DE.
5Picker, can you please advise of the specific circuit board from the Dinosaur site? In case I go to that option.

**wmtire** · 12-19-2018, 12:01 PM

This thread may help, as I have pics of the backside of the water heater, as well as the module boards in it. You can also get the boards tested somewhat if you have a cooperating RV service/dealer nearby. It's explained in the thread below:

http://www.forestriverforums.com/for...ml#post1827312

I'm going to have to think on this though, how the module could cause it "not" to shut off.

It sounds to me almost like the thermostat assembly is not pressed up against the wall of the tank. The thermostat is before the module board. It should cut the power to the board once the water heats up... so even if you have a bad board a properly functioning thermostat 'should' kill power to the board in an infinite heating situation as you describe.

bubbles · 12-19-2018, 12:02 PM

Just a thought. Be sure the DC TS that is inline has red wires attached. The AC side are black wires regardless which side.

ArmyAV8R · 12-19-2018, 12:06 PM

What if the wires red wires connecting the 12V propane thermostat are actually backwards...? Possible culprit?

bubbles · 12-19-2018, 12:08 PM

It's a switch, doesn't matter. I'm surprised the pressure relief valve has not opened with this issue.

**wmtire** · 12-19-2018, 12:14 PM

I edited my post #10 with more thoughts. Please read thru the link/thread I posted and see if it maybe you find something in the pics there.

**wmtire** · 12-19-2018, 12:16 PM

Quote:

Originally Posted by ArmyAV8R

What if the wires red wires connecting the 12V propane thermostat are actually backwards...? Possible culprit?

Can you possibly post a pic of your thermostats with the cover removed? Thanks

ArmyAV8R · 12-19-2018, 12:22 PM

wmtire, I will take a picture this afternoon and post.
But they look exactly like those in the pictures in the link you sent to me.
But I’ll get that picture.

**wmtire** · 12-19-2018, 12:36 PM

Quote:

Originally Posted by ArmyAV8R

wmtire, I will take a picture this afternoon and post.
But they look exactly like those in the pictures in the link you sent to me.
But I’ll get that picture.

Thanks, we can go from there. If you will read post #16 in the link I sent you, it sets forth an order of operation, with each step/part numbered. The thermostat should kill power to the board if it is working correct. The board should receive no power if the regular or hi-limit thermostat opens.

This pic will show a lot of things, like if the thermostat is against the tank wall (it has to be to sense the heat and thus open or close... and if you got the correct 12 volt DC. I don't even think that would really matter in this case of not shutting off.