Gas water heater not turning on

er78mph wrote:
I definitely have gas, I bled the system, and it's an Atwood water heater. I'm just sticking a log lighter when I hear the gas and it stays lit for a few seconds and then turns off.

Sounds like the air mixture sleeve or the thermocouple/flame sensor. Can you slide the perforated sleeve to let more or less air in? Too much air and it will blow itself out, too little and the flame won't be strong enough.

Does the stove top light and stay on?

There is also the possibility you have a clog or something in the flame port. I used to get stink bugs in mine I would have to pull them out with tweezers. Mud daubers will clog them too.

Will the furnace light and stay on. If it will, it will narrow down the problem to just the water heater. It requires similar things to operate. Just a thought.

I definitely have gas, I bled the system, and it's an Atwood water heater. I'm just sticking a log lighter when I hear the gas and it stays lit for a few seconds and then turns off.

Sounds like either the igniter or the flame sensor (thermocouple) or gas is out or turned off.

The thermocouple senses the flame and converts it to millivolts to keep the solenoid valve open. If no flame, the valve closes. It's a safety feature to prevent gas from flowing without a flame. If there is a flame but it turns off anyway, the thermocouple could be bad.

But before all that, check to see if your gas is turned on at the tank. Then check your stove to see if it will light and burn. Could also be air in the line and it needs to bleed. Also check to see if you have LP in your tank and it's not empty. But they close the tanks to fill them and often forget to open them back up.

There could be an air vacuum in your gas lines to the the water heater.

Try turning one your gas stove and leave it lighted. This should flush the air vacuum. Then while still on, see if it ignites the gas in the water heater line.

It's usually a pain specially if your water heater is at the end of the RV and the gas line would have to travel some distance.

You say when you light it with a lighter it won't stay on. How are you lighting it? Is there a button you are holding down to light it? Or are you sticking the log lighter in while the igniter is clicking? When it lights how long is it lit? A few seconds, only until the clicking stops, until the water is hot then it shuts off but won't recycle?

Is it a Suburban water heater?
Is it an Atwood water heater?

When it shuts off what do you have to do to get it working again?