Background: 3500 sq ft house with two heating zones. Downstairs zone heated with a New Water Furnace Premier Geothermal system, the upstairs is heated with a Goodman heat pump, I think its 13 seer, definitely nothing better than 14 seer. There is only one wire running to the Goodman Air handler unit, a 12 Gauge wire at best, far as I can determine, there no Backup / AUX heat on the system. 

Weather: Very cold, going down to the teens at night, sometimes the single digits, in the 20's during the day. 

Mystery: How is the heat pump working at all? I know from my reading that a Heat pump stops extracting heat at around 35 degrees, so how is it working at all? I never really gave it too much thought, after all it some how kept the upstairs warm, so it must be working enough to maintain temperature. 

A clue: After a meter reading last week, I'm once again on the road to another disappointing electric bill; I'm on track for a nice $400+ electric bill. Since I replaced the old downstairs geothermal system with a new Water furnace with Desuperheater, I expected improvements in the heating bills. After all, this is after replacing many of the lights with compact fluorescent bulbs and getting a new energy efficient dishwasher. But I forgot something... Last year I was playing around with set back temperatures and overall getting disappointing results. I felt the bills should be lower than they were with the setbacks I was doing. The whole problem with determining who much your saving is you need a baseline to compare the results with and my problem is I don't have one. I came to the conclusion that setbacks do not work for geothermal, it's better to just leave the temperostat alone. Since I'm the new owner of the house, I don't have any data to compare my figures to. My last house was an 800 sq ft rancher, heated by Natural gas, the highest bill ever was $200, but now I have a house with almost four times the sq. footage, so logically the gas bill should be in the $800 range if I was using similar heating method. 
 
Well out of desperation, last week I began to try and set back the temperatures for the two zones again, the upstairs is programmed to only decrease from 68 to 65 degrees, since past experience has shown me that the recovery time is longer for the heat pump and downstairs I have to manually set from 68 to 64, I turn it down at around midnight and do not turn it back up until I get home from work at 5pm the next day. I figured if I get promising results, I could buy a programmable thermostat later. Early results show the recovery time downstairs if pretty quick, even with the backup heat disabled.   

Getting to the Point: Last night I set the downstairs to 63 and the upstairs is programmed to 65, when I got up this morning it was 63 upstairs. Hmm that's strange, it shouldn't be any colder than 64... Unless the downstairs is heating the upstairs. There a large return at the top of the stairs, what I’m now thinking is the heat from the downstairs to drawn into the return for the upstairs and is pulled thru system and heats the zone. The heat pump running outside isn’t adding any heat to the system; it's just chewing up KWH. I suspect that if I set the upstairs to fan only, and set the downstairs to 68, the upstairs will maintain 67 degrees.
 
Question: when the system is set to Fan only, does it just run and run, or does it it shut off when it reaches the set temp of the thermostat?
 
Any thoughts? 

Well back to the drawing board. Things didn't work out as planned. 

I set the downstairs heat to 70 degrees and turned down the temperature on the thermostat upstairs and switched it over to fan on. I tried to trip the compressor breaker, but the system wouldn't run at all with the compressor powered off. Over the course of 2 hours the temperature dropped from 63 degrees upstairs to 60, even with the downstairs at 70. I had to admit defeat and turn the heat pump back on. It's been running for 4 hours now, non stop, and it's only 63 degees upstairs now. The downstairs recovered from 65 degrees to 70 in just under an hour.

My next great idea is to set the upstairs temperature to a minimal level and get some kind of space heater for the master bedroom. After all me and my wife really only use the master bedroom and master bath upstairs. Other than the computer room and once a week for laundry, the other rooms upstairs are unused.

Maybe i can talk my wife into moving into the dining room downstairs.....

I never understood what the advantage of an oil filled electric heater.  Why would you want this, just curious?

I guess I’m just as confused as before.  I understand thermal mass and that it would take longer to heat this oil (thermal mass) but what is the advantage over a run of the mill resistive wire with fan type heater?  It would seem to me that a fan circulating heated air would cover a larger area, where just having a container of hot oil would be more localized heating.  You totally lost me with the comparison to geothermal.  Sorry….

Also I haven't been running the Electric Heater 24/7, only 3 or 4 hours before bed to get the temp up to 68 to 70 degrees than I set it to Med for the night, and turn it off in the morning. I figure running this way for then month should run me around $40, as opposed to the Air Source Heat Pump, which is costing me at least $200.