Hot water heater

[Eastham]

Hot water heater was working on propane. ran out of propan switched tanks now it lights for 10 seconds and goes out.any ideas.

[Logan X]

Maybe run the stove to purge out any air in the lines.

[sourdough]

How fast did you turn the tank selector? If you just "turn" it there is a high risk of it not working. Turn the valve very slowly from one side to the other so it will switch.

[Eastham]

Stove runs fine .heater goes out after 10 sec relight it goes out in 10 sec..

[Eastham]

If it was the selector would the stove work?and not the hot water heater.

[JRTJH]

Originally Posted by Eastham

If it was the selector would the stove work?and not the hot water heater.

Yes, that's a good possibility. The water heater requires about 15000 BTU of propane to operate, the stove burners are around 3000 to 5000 BTU, so there could be enough propane flowing through a "partially shut off valve" on the tank or regulator and allow the stove to work just fine, but not be enough flow to keep the water heater burner lit. You could easily have enough to light the water heater but not enough to keep it lit.

If you ran out of propane and it's not the safety flow valve that's causing the shutdown, another possibility is that the "last little bit of propane" in the old tank had enough "trash and tank residue" in it to carbon up the flame sensor. In the bottom of the burner tube, you'll find the thermocouple/flame sensor. You might need to use a stiff tooth brush to clean any carbon that accumulated on it. A carbon film will insulate the thermocouple and cause the flame sensor to sense that the flame is out and shut down the flow valve.

If the water heater was working OK and the only thing changed is the propane tank, then chances are that it's not a component failure but rather just a condition caused by the tank change.

[Eastham]

Thanks for the info we will give it a try cleaning it .

[travelin texans]

While you're at it make sure wasp/mud daubers haven't built nest in the burner tube.

[Eastham]

Tec came and turned out to be a bad circuit board. all is working now thanks for all the replies.

[foszoe]

I hate coincidence. I like it much better when something breaks in isolation. My mind always connects the problem to the most recent thing I did and when they are unrelated it usually means I waste a lot of time!

[Eastham]

Totally agree with you.

[JRTJH]

Originally Posted by foszoe

I hate coincidence. I like it much better when something breaks in isolation. My mind always connects the problem to the most recent thing I did and when they are unrelated it usually means I waste a lot of time!

To "ease your concerns about coincidence"....

There may be a connection between running out of propane and the control board failure. When you think about the way the system works, once the propane tank is empty, the water heater will continue to call for gas/ignition/flame for a number of sequence attempts. If there is something "not quite right" with the lockout circuits on the control board, the system may continue to attempt ignition until either the 12 volt battery is dead or until the igniter circuits fail. Also, if the lockout circuit fails, it may not "unlock upon correction of the problem"... If the lockout occurred because of multiple attempts to ignite the "missing propane" then it's possible that running out of propane did cause the control board failure....

The above is not "probably what happened" it is a "possibly what happened".....