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Robert, RV Mechanic
Category: RV
Satisfied Customers: 13355
Experience:  18 yrs. RV experience including Cummins North West, Country Coach, Monaco Coach - vendor certified.
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Furnace will not light properly, if vent is partially

Customer Question

furnace will not light properly, if vent is partially blocked it will light off for a few moments.
New propane service was just connected and tech "says" that flow an pressure are correct, if pressure is too low will that affect burners ability to stay lit?
Submitted: 1 year ago.
Category: RV
Expert:  Robert replied 1 year ago.

Hi my name is Robert.....

Yes if pressure was to low it would affect the furnace. The pressure really should be checked at the furnace with a manometer with another appliance running you should have 11" of water colmun. Go to the main tank and shut the valve, slowly open it back up sometimes if the main valve is opened to fast the regulator can lock up and you might not get the proper pressure.

IF you are blocking the vent off and it is lighting off then I might blow out the exhaust port out really good and make sure it is not plugged up, make sure all your ducting on the furnace is secure. I might also have the circuit board tested to make sure it is not part of the problem, the electrode will sense the presence of flame and send a signal to the circuit board to shut down if it does not see the flame, if it is lighting off and shutting down then it could be the board. Most RV shops have a special tester for that..... Robert

Customer: replied 1 year ago.
Stove has decent flame
so regulated is not lockedExhaust is blowing out strongDSI type ignitor fires and burner lights off
but then immediately goes out .....
unless I partiallyblock exhaust vent
about 50 / 60 %
then will stay on
Expert:  Robert replied 1 year ago.


If it is not a LP problem I would next have the circuit board tested to make sure it is good and not shutting down the flame. I also might pull the gas orifice and soak it in alcohol. Make sure there is also nothing inside the burner chamber, sometimes bees, mud daubers can get inside and cause problems, have seen that a few times. Air flow is crucial for these to work properly..... Robert

Customer: replied 1 year ago.
It's some kind of air flow issue for sure
I will re-pull the cover and lookNot much room to work on from the outside
Expert:  Robert replied 1 year ago.

understand, I might pull the unit and give it a good cleaning and make sure all the gaskets (if you have any) are not leaking, sometimes you will find covers that require gaskets. You would have to pull the furnace from the casing to access. Not sure of your make and model

One thing also I would verify your battery voltage when this is happening, make sure you have at least 11 volts DC...


Customer: replied 1 year ago.
All 120VAC power
40 ft park model 1998Furnace is an atwood
Expert:  Robert replied 1 year ago.


I might pull that out and inspect it on a bench and clean it all out, if something was inside it would cause this issue, I would also clean that gas orifice and see what happens...