Suburban water heater gas valve stays open no flame

[isonychia]

I have a new Suburban SW6DE installed in my trailer.

It was working fine.

This weekend I noticed a propane smell coming from the exterior door on the heater. I am almost positive it was coming from the gas valve and NOT the gas connection compression fitting.

I was not getting a flame at the heater but I could smell gas. This was not the exhaust smell but propane.

Is it possible I need a new module board?

I thought all appliances like this had a system that would not allow propane to flow unless it senses a flame.

Before I go out and buy a new module board, any ideas?

I could buy the board and if I don't need it I could return it.

Thanks,
iso

[isonychia]

dougrainer wrote:
1. The Water heater Safety will NOT allow gas to flow thru the gas valve if no flame is present. The gas Valve opens for about 7 seconds on an ignition sequence. IF the Piezo fails or the flame does NOT light the gas valve shuts down. It will do this for 3 tries about 30 seconds apart.
2. BUT, those 3 tries will cause 21 seconds of LP to flow and THAT will cause a odor in and around the water heater. Long after the sequence stopped.
3. LEAVE the LP tank valve OFF. Start a LP ignition sequence and observe the water heater. See if the Piezo sparks and sparks a GOOD spark with a good gap between the probes. A common mistake novices make when installing a water heater(if you installed it) is to pull the Ignition spark plug cable away from the electrode Spade terminal inside the orange/black rubber boot. Pull back the boot and see if the wire is connected and secure on the electrode. IF no spark and the connections are good, go to the Ignition module and verify the Electrode spark nwire is indeed still connected to the control module. If so, then the Piezo tower on the board is bad. Doug

PS, I will bet your input gas line connection may not be tight and is also leaking,

Hi Doug,

Thanks for the info.

I did install it myself. It was simple and straightforward.

I will check the spade terminal and see if I accidentally pulled on it somehow and disconnected it.

iso

[dougrainer]

Chris Bryant wrote:
Those gas valves fail all the time, my money is on that.

The only gas valves I see fail are the ATWOOD Gas Valves. I cannot remember the last time I had a Suburban Gas Valve fail. Besides they are dual valves and that is the redundancy of keeping the gas from flowing. Especially on a new water heater. The Atwoods do not blow gas, they seep a small amount when they fail after years of service. Doug

[Chris_Bryant]

Those gas valves fail all the time, my money is on that.

[dougrainer]

1. The Water heater Safety will NOT allow gas to flow thru the gas valve if no flame is present. The gas Valve opens for about 7 seconds on an ignition sequence. IF the Piezo fails or the flame does NOT light the gas valve shuts down. It will do this for 3 tries about 30 seconds apart.
2. BUT, those 3 tries will cause 21 seconds of LP to flow and THAT will cause a odor in and around the water heater. Long after the sequence stopped.
3. LEAVE the LP tank valve OFF. Start a LP ignition sequence and observe the water heater. See if the Piezo sparks and sparks a GOOD spark with a good gap between the probes. A common mistake novices make when installing a water heater(if you installed it) is to pull the Ignition spark plug cable away from the electrode Spade terminal inside the orange/black rubber boot. Pull back the boot and see if the wire is connected and secure on the electrode. IF no spark and the connections are good, go to the Ignition module and verify the Electrode spark nwire is indeed still connected to the control module. If so, then the Piezo tower on the board is bad. Doug

PS, I will bet your input gas line connection may not be tight and is also leaking,

[isonychia]

Old-Biscuit wrote:
Make a soapy solution (1 TBSP dish soap/water in spray bottle)
With the propane valved in for service
Spray the propane line connection at gas valve and check for bubbles

Do NOT spray the outlet side of gas valve ...you will clog up the orifice

IF no leaks on line/fitting ...rinse with clean water

Then using a BBQ lighter see if you can ignite any propane at end of burner tube


Gas valve ----requires both solenoids to open gas valve.
One alone will not open it.
Propane system pressure is only 0.4 psi (11"WC)
12VDC is applied to gas valve solenoids for only 6-8 seconds during ignition cycle....during which time spark electrode is energized
Spark Electrode is also used in 'flame proving' circuit.......milliamp signal generated by FLAME which is detected by circuit board. No Flame signal...No DC to gas valve solenoids (easy to check with voltmeter on gas valve red/black wires)

Gas valve 'could' leak....rare but possible

Circuit Board.....could be faulty (doubt it)
If faulty it is more likely it would NOT send DC to gas valve or not send DC to spark electrode
HVAC guy sounds like a parts changer. Which eventually works if you throw enough parts at it.


Here is the wiring diagrams for 12VDC (propane) and 120VAC (element)
Maybe the HVAC guy can figure it out

Thanks for the detailed info, I really appreciate it.

I know my friend is not a novice at his HVAC trade. He runs his own business a lot of it commercial etc. for many years, He has taken care of a lot of stuff for the camp trailers and knows his stuff. Granted I know he has not spent his years servicing suburban rv water heaters.

He suggested we look at the heater more in detail this weekend. He suggested getting the board so we had it in case it was a problem.

As soon as I smelled gas, he quickly looked at the unit, then told me to shut it off.

The heater is brand new. It was working fine for the 3 weekends I have used it. I just happened to be sitting near it on Sunday and I mentioned to him I smelled propane.

I didn't think with all the safety measure in place it was even possible for the unit to fail this way. (expel gas with no flame present).

We will know more this weekend.

iso

[Old-Biscuit]

Make a soapy solution (1 TBSP dish soap/water in spray bottle)
With the propane valved in for service
Spray the propane line connection at gas valve and check for bubbles

Do NOT spray the outlet side of gas valve ...you will clog up the orifice

IF no leaks on line/fitting ...rinse with clean water

Then using a BBQ lighter see if you can ignite any propane at end of burner tube


Gas valve ----requires both solenoids to open gas valve.
One alone will not open it.
Propane system pressure is only 0.4 psi (11"WC)
12VDC is applied to gas valve solenoids for only 6-8 seconds during ignition cycle....during which time spark electrode is energized
Spark Electrode is also used in 'flame proving' circuit.......milliamp signal generated by FLAME which is detected by circuit board. No Flame signal...No DC to gas valve solenoids (easy to check with voltmeter on gas valve red/black wires)

Gas valve 'could' leak....rare but possible

Circuit Board.....could be faulty (doubt it)
If faulty it is more likely it would NOT send DC to gas valve or not send DC to spark electrode
HVAC guy sounds like a parts changer. Which eventually works if you throw enough parts at it.


Here is the wiring diagrams for 12VDC (propane) and 120VAC (element)
Maybe the HVAC guy can figure it out

[isonychia]

I suspect the control board because an HVAC engineer at the camp ground suggested it could be the control board.

You are right joerg68, I am not sure what the problem is.

I will spend some time up there this weekend and look into it fully with the HVAC guy.
I wanted to ask the question here and see if there was any ideas.

I will order the control board and return it if it's not the problem.

[joerg68]

Why are you so sure that there is no other leak and the main valve is not shutting off correctly?
There is some form of solenoid that cuts off the gas flow when no flame is present.
There is some form of thermocouple that senses the heat.
The system could fail in a number of ways mechanically (stuck solenoid, loose connection, for instance) - the control board would not be my first suspect.
Propane can be real dangerous. Take care, and take it to a professional if you are bot sure what you are doing.

[DarkSkySeeker]

isonychia wrote:
Is it possible I need a new module board?

My board died. Although I did not smell gas, I could hear the main valve open, but could not hear the electrostatic spark. I had a mobile repair tech come and replace it under warranty. It took more time to find my warranty paperwork and pay him than it did to replace the board. The new board is still working 2 years later.