We have a propane heater. We have propane in the tank. There is air blowing through the vents, but there is no heat. Usually, there is a clicking sound in the thermostat, a whumph sound in the heater and the heat comes on. Now there is no clicking sound and no whumph. Consequently, no heat. My husband and I went out to the heater room and he showed me where the pilot light was on. Any help would be appreciated.

Thank you,

Suzanne

Armstrong ultra 80's often had what is called a honeywell smart valve, it uses a small, 24 volt, hot surface ignitor to light the pilot light. There is a small metal rod in the pilot flame that must pass current through the pilot flame before it will turn on the main burners. You can try to clean that flame sensor, very carfully, it's not that easy to do, and not break the ignitor. If that doesn't work you will probably need a new smart valve. They are quite expensive and I have seen many problems with them. Then again this might not be your type of ignition system at all.
Good Luck

Dear Northern Heat,

Thank you for your reply. We now have additional observations. Late this afternoon, my husband went out to check the heater and he said that it was running properly. The house did start to heat up. Now it is evening again and the temperature is dropping again. Is there something that could be failing as the ambient temperature drops?

We are in Western Washington and have had snow on the ground for several days. It's been very cold outside since this problem has developed. The heater is in a little, unheated room on the outside of the house. It's attached to the house, but there is no access from inside the house. It shares the room with a Space-Gard air unit and a propane hot water heater.

We have never had to do our out heater maintenance. Assuming that the problem is as you have described above, would the wisest course be in contacting a professional?

Yes, they can clean or replace the sensor, you should get a guarantee, if this is an intermittant problem the service tech may have problems finding the cause since it is hard to fix something that is working.

Too true. I once workined a computer repair shop. The techs absolutely hated the intermittent problems because they had to figure out how to make the unit fail before they could diagnose and fix it.