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Propane furnace help needed

1K views 8 replies 6 participants last post by  Falfrenzy 
#1 ·
I had a service man out but he’s keeps saying it is the thermostat. I hot wired the thermostat and the Furnace still don’t work, don’t want the service man to come back out since he seams incompetent.

The symptoms are:
the Furnace will light and run for a few seconds.
It is a three year old high efficiency Furnace.
The indicator lights say the Furnace is good.
I teed into the propane line just before the furnace, shut off the furnace, hooked up a portable blue flame heater, had the same results.
The gas gas stove in the kitchen works fine, will run all four burners at once.
The tanks is 50%full.
The system has two regulator one on the tank and one outside the house.
Some times the furnace will run like it is supposed to.
The colder it gets outside the less the furnace functions properly.

I am thinking it has to be a regulator problem. Any help would be appreciated.
 
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#3 ·
Sounds like a regulator freezing up. Take a hot cloth and wrap it around them to heat them up. If frozen you should see improvement while they stay hot. By doing one at a time once this proves to be the problem, do one at a time to refine which one is the problem child. You may need a new regulator.
 
#4 ·
Another thing I have experienced is that this happens when the condensate drain freezes up.

The pressure of the propane in the tank can be very high depending on the temperature. One hundred fifty PSI is not unusual. The regulator on the tank is a high pressure regulator. It cuts the pressure down to somewhere between 10 and 60 PSI. You need this pressure to push the propane through the line to the house. Here, in my county, the tank needs to be at least 10 feet from the house, most are further. The regulator on the house cuts the pressure back to a little more than 1/3 PSI which is what the appliances run on.

You have tested that the stove works fine so the line to the stove is good. The furnace burns more propane faster than the stove so it may not be getting enough. To be certain you will have to hook up a pressure gauge. The pressure at the furnace should be a little more than 1/3 PSI AKA 11 inches of water.
 
#5 ·
Yep, I would suspect a regulator problem. They are cheap and easy to replace. The other unknown factor is what size the lines going to the furnace are and if they are insulated from extreme cold.
 
#6 ·
I reset both propane regulators by turning a burner on the stove, **** off the valve on the propane tank, go back in the house to shut the stove knob off as the flame has burnt itself out. Go back out to the tank, SLOWLY turn it back on.

The furnace ran good for about 10 minuets then states giving fault codes. After the first ten minute run it would only fire for about a minute then give a different fault code. It would turn the electric switch to the furnace off for a minute then back on. The burner would light for minute then die. On all it gave four different fault codes.
Then I reset the regulators again, this time I put the cover back on the furnace, it has been running good since. Note: the cover didn’t not have a switch telling the furnace it was in place.

My thought is; the furnace didn’t draft right with the cover off. Temps outside have been mild since I last had trouble. The next cold snap ( sun zero) will be the test.

Also the 4 burners on the kitchen stove burn way more propane than the 3 little burners on the furnace.

Also, the line from the last regulator (1/3 psi) is piped through the unheeted attic.

I will keep you posted.
 
#7 ·
When it gets down into the teens my stove and furnace both act-up..so i put a 60 watt
light bulb under the valve cover on the lp tank...Everything works fine then...Ferril gas
dude got ticked off...said not to do that any more...wrote me up on the ticket...So
after he left I put it back...
 
#8 · (Edited)
First thing to try is replace the thermocouple if it has one. If it's dying it acts like what you describe. Also this is the simplest and cheapest thing it might be.
You're close, but H.E. furnaces dont have thermocouples, which require a constant pilot light. Studhauler needs to clean off his flame sensor, as scale will build up over time and impede its ability to tell the gas valve "steady flame, go ahead and open the main valve"

Studhauler, don't use anything more abrasive than steel wool, or else you can damage the flame sensor.

" My thought is; the furnace didn’t draft right with the cover off. Temps outside have been mild since I last had trouble. The next cold snap ( sun zero) will be the test. "

Incorrect. H.E. furnaces dont care where they get their combustion oxygen from for the burners. And your "draft" motor (inducer motor) has to spin up and move enough air thru the flue/exhaust pipe to close a pressure switch before it will allow the HSI (hot surface ignitor) to begin to light.

You don't have the furnace installed in a closet with a solid door do you? If so, you need a pipe going outside to bring in fresh air for the burners to run.

Curious, what diameter and pipe material is the gas supply line to your furnace? And what size supply tanks do you have?
 
#9 ·
When it gets down into the teens my stove and furnace both act-up..so i put a 60 watt
light bulb under the valve cover on the lp tank...Everything works fine then...Ferril gas
dude got ticked off...said not to do that any more...wrote me up on the ticket...So
after he left I put it back...
You have let the level of LP in the tank get too low. Don't let it drop below 30% full. You need vapor, not solid liquid. Re-fill when 40% low in really cold weather.
 
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