The main problem we are having with the unit is the auxilary heat is on 90% of the time. Our electric bill is through the roof. History: We bought a Tranquility 27, 5 ton in May 2006. In the first year the unit in the heating cycle would turn the auxillary heat on at around -5 c.( We had to turn the auxiliary on as ice appeared on the pipes leading into the furnace and the unit was not able to heat the house). We live in southern Ont. and in an older home 2200 sq/ft. unheated basement .( new outside doors, some new windows, new insulation installed in some walls, no drafts) Present: Since November 2008 our unit has been running all the time either on heat or auxillary heat. It never shuts off. It does not matter if it is 2 degrees celcius outside or -28 c. The unit is always running in both modes. Service tech said it was the filter. We changed the filter and still had the same problem. Tech came back again on Jan 7th, all pressures and temperatures were fine he said. He told us to turn off the auxillary breaker and see what would happen. Within 2 hours the temp. started dropping the unit was unable to keep our house at 20c. After it dropped by 5 degrees we had to turn the auxillary heat back on. Service tech said he would come back on the 19th. When he did not show up, called the company and he said he would be out in a few days but thought it was our unheated basement causing the problems. On Jan. 22 new service tech with a different company came out at our request, he agreed there was a problem and was very helpful but still could not find the problem. There were no code errors showing in the furnace, but he felt that the temperatures leaving the furnace should be 10 degrees higher. (He measured 90 degrees F at the furnace( heat pump ) Temperatures taken at floor registers vary, 69-73 F when the geothermal is on and 81-83 F when the auxillary is on. (Although once I did see a reading of 100F on auxillary) This furnace is costing me a lot to heat my house Please can anyone give me some ideas on how to fix this problem. Thanks.