Duo-Therm.....

[mrcaptainbob]

My son has a hunting camper on the west 20 with a Duo-Therm propane furnace. It's not working. The furnace info is:
Duo-Therm L0120917
MODEL 65930054
INPUT 30K / OUTPUT 24K
12V 6.5AMP
AC/DC

Although the pilot lights and stays lit, the furnace will run for about 30 seconds and shuts off. Also, as soon as power is turned on to the furnace, the blower kicks in. An interesting issue is the thermostat. If it's adjusted above the mid 60's the furnace kicks in. If it's adjusted below the mid 60's the furnace kicks off.
My son removed some sensor and found the ohm rating to not be 'correct' for the temp registered. Do not know where he got that info from. It's an electrical sensor and not the thermocouple.
What can I do to find the problem?

[HayZee518]

room temperature should be entirely dependent upon the room thermostat. air flows across the thermocouple shouldn't be so drastic as to blow out the pilot valve. the thermocouple with flame about it opens a permissive to allow the main valve to open. loss of thermo power closes the pilot flame valve.
Does the pilot flame extinguish after a certain time delay? Then I would look towards the pilot flame detect. Pressure to the heater should not exceed 5 psi. propane or natural gas.

[mrcaptainbob]

The pilot flame stays lit, HayZee. The flame that goes out from 'wind' pressure is the flame on the hand held igniter. Just when passing the flame through the window port is when the flame may blow out. But turning the thermostat UP will keep the furnace blower off! It's easy to light the pilot at that time. Then, by turning DOWN the thermostat will kick the furnace blower in and immediately the burner comes alive, too. After maybe thirty seconds, the burner and pilot go out. But the blower remains running.

[HayZee518]

I don't understand what you mean by a hand held ignitor.

[mrcaptainbob]

One of those butane gas grille lighters.

[HayZee518]

what you might try is lowering the input gas pressure on the regulator. 5-6 psi is normal for gas appliances. if your appliance comes off a bigger bulk tank that feeds multiple appliances the pressure regulator is around 11.

[mrcaptainbob]

It works off pf those portable propane tanks. Even a gas grille sized one works. How can I check the that pressure?

[HayZee518]

normally a liquid manometer is used. but I'm sure someone has a dial type