I'm the second owner of a 3500 sq. ft. home with a geothermal HVAC system. The home is built on a slab with 10' ceilings. The heat pump and all ductwork (insulated flexible ducts) are located in the attic. The system currently has three zones. I have been happy with the comfort (except for the compressor noise) and cost of operation of the system---- in all but the very coldest weather. When the outside temperature goes below about 10 degrees the electric consumption skyrockets because the auxiliary electric heat cycles on a great deal. I am trying to determine what "minor" changes I could make to reduce the amount of time that the auxiliary heat is on. I am not a HVAC professional, so I need some assistance in understanding how my system functions. My heat pump is a Climatemaster Tranquility 27 model TTV049 The three thermostats are Honeywell TH8320 The zone control is a Jackson 300HPS I can monitor my electric consumption by using the daily consumption figures provided by the local electric utility. Degree day information is readily available on the internet. I don't have much additional information about the system since I am the second owner of the house. I do know that it is a closed loop system with four vertical wells of unknown depth. The system is regularly serviced by the company that installed it, but I don't have any specific information on pressures, temperatures, etc. The rather loud compressor noise transmitting thru my ceiling lets me know when the compressor is running---which is nearly constantly during very cold weather. The thermostats tell me whether a zone is calling for heat---but do not tell me whether the compressor is on the first or second stage. The only way I can determine whether the compressor is running on the second stage is by viewing the lights on the zone control panel. This is a problem for me since the unit is in the attic and I don't climb stairs well. The thermostats also will show an "aux heat on" message at times. This message may be shown on only one thermostat, two thermostats, or all three thermostats. The home was built for a disabled man and his elderly caregiver. It originally had two zones. One was an "enclosed porch" with is a long, narrow room with mostly glass (windows and atrium door) on two sides. I think that it was intended for a spa/exercise room of sorts. The second zone was the remainder of the home. The thermostat was located in a "dead air" zone in a hallway between two bedrooms. Sometime after moving into the home the man decided that he liked his bedroom cool and his caregiver liked her areas very warm. They had the main part of the home divided into two zones with a second thermostat located in a hallway outside the other two bedrooms on the far side of the house. We have set the "porch" zone at 62 degrees because we don't use it often. The other two zones are kept in the 65 to 67 degree range---depending on how we feel on a given day. We do turn down the zone where our bedroom is located to 64 degrees during the night because we sleep better with a cool temperature. In very cold weather when we turn the thermostat back up to 66 the temperature seems to rise to about 65 degrees, then drop back to 64 degrees and the "aux heat on" message will appear on the thermostat in one of the other two zones. When I walk around the house there feels to be very little air flow from any of the ceiling registers. I suspect that increasing the set point on one thermostat is causing the auxiliary heat to kick in, and that the hotter supply air is stratifying near the 10' ceilings and not reaching the thermostat that was recently changed. I have looked a the programming on all three thermostats. They are identical with a first stage cycle rate of 3 and a second stage cycle rate of three. I have noticed that the system may run for an extended time with the "aux heat on" message showing on one or more thermostats, then the system will shut off for a few minutes. (All thermostats have the compressor protection set for five minutes off). The heart of the matter is that I don't understand how the three thermostats function in combination with the zone control. Can someone explain: 1. What controls the progression through the stages? (is it based on time or temperature differential?) 2. The auxiliary heat is either on or off. Why don't all thermostats show the "aux heat on" message when the auxiliary heat is on? 3. I'm not really concerned with temperature on the enclosed porch (as long as it stays above 55 degrees). With all the glass, it's the zone most likely to drop below the set point. Can I change something to prevent a small temperature drop in this one room from causing the auxiliary heat to come on? 4. The compressor does seem to cycle on and off even in zero degree weather. I don't know whether it is cycling between 1st and 2nd stage. Is it possible (or likely) that this cycling coupled with having multiple zones is causing the system to use the auxiliary heat rather than the 2nd state heat (because of the cycle rate specified?) 5. I don't currently have a way to measure static pressures in the system or the cfm delivered at each register. With ceiling registers and 10' ceilings the warm air seem to stay above my head level. Would increasing the blower speed help (if it is possible?) 6. I like the ability to keep the enclosed porch at a different temperature than the rest of the house---so long as it doesn't increase my costs by causing the auxiliary heat to run more. Would it be more efficient if I recombined the other two zones? (The only reason we keep one zone hotter or cooler than the other is an attempt to save money.) 7. Based on the information I have presented, does anyone have any suggestions what else I should consider?