Heat Pumps and Electric Heating - Duel Fuel Heat Pump

We have a Trane heat pump and a dual fuel kit installed which uses propane. The unit is about 10 years old now. I don't think this thing has run correctly since the first year. The problem is that when the ignition cycle starts most of the time the gas doesn't flow and it doesn't fire. I thought this was a sticking gas valve for a long time and would hit the valve body with a screwdriver handle until it finally would fire. Two years ago I replaced the gas valve and thought that should do it but I have the same problem. Last night the house got down to 64degrees. I was down in the basement shutting the power off and on to force repeated ignition sequences until the thing finally fired. I am sick of this and am ready to take a sledge to the whole system. Other symtoms that may be related is the heat pump will run set on 70º but allow the house to go down to 66º before I will try to get the propane to come on and get the house back up to temp. Also the heat pump runs while the aux demand light is on in the thermostat and the differential between the setting and house temperature is 4-6degrees. It seems to me that the heat pump should go off when gas demand goes on. I have had some luck by turning the mercury switch to where gas demand just goes off and then by setting the switch so it's just on. This will shut off the heat pump and start the ignition sequence but as stated above the gas doesn't always fire. I live in PA and it was about 25º last night.

Any ideas?

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Programmable Thermostats (http://www.prothermostats.com/)

Sounds like you need to get your furnace checked out and/or debug what's ailing it. It could be something as simple as a worn out igniter or dirty temp sensor.

4°-6°F differential before bringing on the aux is a bit much, and solely the function of your tstat. You should dig into the manual to see if that can be changed or just replace it.

Aside from the waste there are some issues with running your aux furnace and HP in tandem, particularly if the indoor coil is downstream from your furnace. Typical hybrid installation do not have them running together, but in your case it might be the only thing keeping you from freezing. So we'll call that a fortunate mistake.