Hi;

We have an older LP gas furnace and water heater. If the water heater burner is going and the furnace burner lights, the furnace burner will not stay lit. The furnace keeps cycling off and relighting. The pilot and burner shut off for a few seconds, then the pilot lights, then the burner lights and burns for a very short time, and then the cycle repeats itself.

When I turn the water heater control to "Pilot Only," then the furnace burner seems to run fine. Do we have a gas valve problem? If so, is it in the furnace, or is it the one on the outside of the house where the gas line comes into the house? Please help. We appreciate your help.

Thanks,
Alan

It seems more like a low pressure problem to me. It could be possible the regulator off the LP tank is not functioning right to allow enough volume at set pressure to burn heater and furnace both at the same time which is what's happening.

Not sure how the LP hook up is and if its in tandem etc

Since both units burn good when one is off or the other is off I would definitely suspect the reg from bottles to house.

I replace the Reg. on the out side of the house.

Just on a side not do you have a 6" drip leg on the hard gas line for the heater and furnace. If not that should be done. Its a T fitting with a 6" min drip leg capped. This prevents moisture from getting in the gas valves on heater and furnace. Each unit should have one right before it piped into there gas valves

Signed 21 Boat

If I Helped To Answer Your Question Please Rate My Answer

[QUOTE=21boat;1577337]It seems more like a low pressure problem to me. It could be possible the regulator off the LP tank is not functioning right to allow enough volume at set pressure to burn heater and furnace both at the same time which is what's happening.

Not sure how the LP hook up is and if its in tandem etc

Since both units burn good when one is off or the other is off I would definitely suspect the reg from tank to house.

I replace the Reg. on the out side of the house.

Just on a side not do you have a 6" drip leg on the hard gas line for the heater and furnace. If not that should be done. Its a T fitting with a 6" min drip leg capped. This prevents moisture from getting in the gas valves on heater and furnace. Each unit should have one right before it piped into there gas valves

[B]Signed 21 Boat

The LP is hooked up in series, I think; the pipe comes in, goes to the furnace through a "T", and then the pipe goes from te "T" to the water heater.

I see two bolts on the regulator; are they adjustable, and if so, how do I adjust them?

I believe 21boat is on the money, suspecting your main LP regulator. Adjustments should only be performed by a qualified individual with the proper tools/instruments to do so. Contact your LP supplier, this might be their responsibility.

Yep, time to have the lp supplier out to have a look at the regulators. Both primary and secondary(one red, on the tank, and the other green, at the house.). Pressures need to be checked. Propane is not something the average homeowner should be messing with. Get in a pro. Please let us know what they find. Do not attempt adusting pressure yourself.

Sorry LP gas user. KC13 is 100% correct about leaving it up to a professional. LP is an explosive!

If you have a service contract with the gas company call them. They might fix the reg as part of there service. Either or they know that exact reg you need and ask them how much to replace.

Signed 21 Boat

If I Helped To Answer Your Question Please Rate My Answer

And this is assuming that it used to work good. Then it has to be the valve or some blockage in the line. But if this has always been a problem , If the gas line is not large enough to handle the volume to run both

Hello Father... is the, umm... confessional open, by chance... for drop-ins?;)

Hi again;

Thanks for everyone's help. We called the LP supplier; they maintain the tank and the regulators. They changed both the regulator at the tank, and the one on the house. They tested the pressure and it was still too low. So they replaced the line and now everything works fine. Thanks again for all your advice. It helped us out.

Glad to here it worked out. Any problems pop up later of what evers just post .
There's tons of good people that are here to help.
Just post it.

Glad to hear they got you all fixed up.