Water heater won't light

[thedoc]

I have a winnebago with Atwood water heater-has electronic ignition. The water heater won't light. I'm not sure if it's because the propane tank valve was just opened and it takes a while for the propane to reach the tank. Ive been trying for two days to get it to light. I can hear the ignitor working when it tries to light. The same thing happened a few weeks ago but eventually it lit. This time it will not light. I was wondering if the solenoid gas valve might be bad-and if so, how do I test it? Thanks.

 

[Lou Schneider]

Try lighting a burner on the stove using a match or butane flame lighter.  This will tell you if propane is flowing from the tank and if there's air in the line.  If there's air it may take a few seconds to purge out through the stove burner - a sure indication of air being present is if the gas (air) coming out of the burner blows out the match or lighter flame instead of igniting.  Yellow flickering in the flame indicates some air is still coming out with the gas.  When the flame burns a steady blue you've eliminated the air between the tank and the stove.

Hopefully this will also eliminate most of the air between the tank and water heater.  All that should be left is the air in the line going to the water heater after it branches off from the main line.

Before you try lighting the water heater again, look for anything that may be plugging the gas tube going from the valve to the burner.  Insects are attracted to propane and sometimes you can get a spider web in the orifice where the gas exits the valve.  Or there may be debris on the burner itself.

 

[Gary RV_Wizard]

Lou gave good advice. I would not suspect the gas valve - a failure there is very rare.

Observe the flame form the outside access panel while somebody else flips the switch. Does the burner light and then go out several seconds later, or does it not light at all? Can you see the spark and hear it "click"? One possibility it that the igniter somehow got bent slightly out of position and it too far from the gas flow.

 

[thedoc]

I just discovered how to make it work but don't know why. If the coach battery is engaged the water heater will always light. If I'm only on shore power without coach battery, it will not light. If both coach battery and shore power is engaged, it will light. Is that normal or is there some sort of problem with the water heater? The power for the rest of the RV is totally normal on either coach battery or shore power.

 

[Alaskansnowbirds]

That is normal. The control board on the water heater has to have 12vdc to operate. Without 12vdc neither the water heater or the refer will work.

 

[Alfa38User]

Just to add to what Don above said, it indicates that, in this case, the heater is not on a 12V circuit that is supplied from your converter (or the converter is turned off). Hence, no 12V, no operation even when connected to 120V .

I think you could fix that, if necessary, by simply leaving the battery on or rewire to a converter supplied circuit.