Is it more advantageous to have a 2 stage GHP than a 1 stage GHP? Is it more economical to have the 2 stage in terms of utility bills? or is it the performance that is different?

Thanks,
Connie

Benefits of 2 stage:

1) Better ability to handle zoned system
2) Higher efficiency when in 1st stage
3) Quieter blower operation when in 1st stage
4) Better dehumidification during air conditioning season.

Primary disadvantage of 2 stage is extra cost - increased efficiency may take many years to pay back the higher upfront cost. Installer has to deal with slightly increased complexity, and repair costs down the road may be higher - blower, compressor and control board(s) all likely more expensive to replace.

I personally believe 2 stage is worth the cost where I live in Florida, but your preferences, application conditions and climate may prove better for a single stage unit. A good contractor will help you decide based on your situation.

I called my installer/contractor just now. He explained to me that he used one stage system on a split system (2 story and 2 zone)- we have 3 ton. So it is 1-1/2 ton each. He said that the 2 stage is applied when the system carries more than 2 tons.

I hope so...  I just ordered a 2 stage 4 ton GSHP to replace a 27 year old natural gas forced air furnace.

Think of it as a heat appliance with a throttle.  With a single stage unit, you go racing full throttle up to the next stoplight then screech to a stop.  Race up to the next stoplight at full throttle then stop.  And again and again and again.

Not the best way to economically operate a car nor a home heating unit.

Connie,
I have recommended 1 stage systems more than a couple times in the last 2 months. Every home has it's own requirements.
A good contractor who does a heat load calc and operating cost comparison can show you why 2 stage units don't alwas make sense.
You've indicated that you are pleased with your system so far,.....That trumps all of our opinions.
j

Hi Joe! So far the system works fine especially now the temperature outside has gone low (about 25 degrees-New Jersey). We have to bring down the thermostat 2 notch below (from 70 degrees to 68 degrees) as the auxialliary heat has kicked in. It still comfortable. Hope my first electric bill with geothermal will still be reasonable this December.

Here are my numbers provided by my contractor "after" the onsite evaluation.  I'm not an HVAC engineer but understand Btuh and such.

Design Data:	Comfort Conditions:
Heating Load: 51,000 Btuh	Heating Setpoint: 68 °F
Heating Temp Diff: 68 °F	Cooling Setpoint: 74 °F
Cooling Load: 30,000 Btuh	Start Cooling Temp: 74 °F
Cooling Temp Diff: 17 °F	HW Temp Setting: 130 °F
Constant Fan: No	HW Users: 3 people
Design City: MINNEAPOLIS, MN	Annual Loads:
Winter Design: -12 °F	Heating: 109.9 million Btu
Summer Design: 92 °F	Cooling: 14.6 million Btu
Bldg Bal Temp: 56.7 °F	Hot Water: 17.3 million Btu
Internal Gains: 8,490 Btuh	HW Use - Daily: 55.0 gallons

Thoughts?