I had my broke 20 year old 2.5 ton Water Furnace replaced with a 3 ton Century geo back in Sept. The water Furnace had a single stage compressor and aux heat. Aux heat ran a lot in cold weather. The Century has a 2 stage compressor plus aux heat. It finally got cold this last week with temps in the low 20's and wind. The geo would go from stage 1 to 2 to aux then off and keep the temp right at 70. Yesterday it was in the high 20s, little wind, stat set at 68 and it ran in stage 1 almost constantly, shutting off now and then but kept the temp steady at 68. I set stat to 67 before I left for work, got home and it is 7 outside, no wind and running stage 2 then dropped to stage 1 and holding steady at 67. Should it be running constantly without shutting off? I have a closed loop with water temps in the low 30's, which leads to my next question. My stat is Heat Controller, INC. communicating thermostat. When I go into system status it says the leaving water is 3 degrees warmer than the entering water. When I check at the unit in the ports with a thermometer is is the opposite. I'm assuming wires are crossed somewhere. Would this cause any problems with operation? My water temps are 31 entering and 34 leaving checked at the unit. opposite at the stat. I am firing up the wood stove to give it a rest and get it to around 75+ in here. Thanks for any input.