I posted about our problems in a previous thread.. To not have to re-hash, I had a geothermal install done with a 3 ton ClimateMaster Tranquility 30 (replacing a 3 ton HVAC electric cool/gas heat) that went very bad. The installer refused to finish the job and fix whatever was causing runaway energy bills. We contacted two other contractors who both agreed that the zoning system was improperly installed and that there was probably not enough loop (I estimate that there was maybe 600 feet of loop installed using horizontal boring).

One of the contractors came out and bypassed the zoning system completely. They flushed air from the lines and pressurized them - finding and fixing 4 leaks that were all loose connections inside our basement where the install happened. They also replaced the thermostat with one from ClimateMaster that gives us information on the status of the unit (entering and exiting water temps, for example). From that point, the system has been at least steadily heating the house. We've been seeing exiting water temps of 40 and entering temps of 46 - almost always 6 to 7 degrees difference - and leaving air temp always 95 or above.

We went away for Thanksgiving and I had the system set to 60. When we got back, I set the system to 71 and it's been heating for the last 2 hours at least. The thermostat now shows 27.1 leaving water temp and 31.9 entering water temp - a difference of less than 5 degrees - and a leaving air temp of just 88.7. The pipes leaving and entering the unit are covered with a layer of frost/ice now.

My question is this: is this a sign of an inadequate loop size?