I am still confused on what Stage 1 and Stage 2 settings mean in geothermal terms. Presently my thermostat is set at 70F but since it is cold outside is has been running 69F stage 2. It may reach 70F and it may not. What does it mean if it runs on stage 69F and never reaches the set point of 70F. I have a waterfurnace system and thermostat.

Assuming everything was designed, installed, and running correctly, it is fine for your unit to run in 2nd stage. 2nd stage is the full compressor capacity of your system. 1st stage is roughly 2/3 compressor capacity. Generally, 1st stage is a bit more efficient than 2nd stage, but systems are designed to use both stages, so no worries there.

When it is cold outside, it is fine for your system to have long run times. As long as the thermostat is within a degree or two of the your thermostat set point, auxiliary heat is not needed. If the inside temperature drops more than this, aux heat is needed. If the system is keeping up with the thermostat, no need to do anything manually to get aux heat running (like adjusting thermostat settings.) Aux heat does bring down the overall efficiency of the geothermal system, but there is no need to use aux when it is not required. At some outside temperature (near the design or balance point of the system) aux will be needed, and that's ok.

I'm typing this in a rush, so feel free to ask follow up questions. :-)

Another question. What would the difference in electricity use between the two stages

You should be able to download a Specification Catalog from Water Furnace for your model. Remember that while electricity use is greater in 2nd stage, you get more BTU output as well.

Depending on your reason for asking the question, COP for your unit may be something you want to look at. These specs (and lots more specs) should be in the same catalog I mentioned. Others here more experienced than I can better answer electrical questions.

Posted By Michel Starenky on 02 Feb 2011 09:07 AM
What would the difference in electricity use between the two stages

Similar to the difference in heat output. Stage-1 uses about 66% as
much electrical power (kW) as stage-2. However, for a given amount
of heat (BTUs) delivered, stage-1 uses less energy (kWh), due to its
higher efficiency.

If you tell us the heat pump make & model, loop type (open vs. closed),
and geographic location, we'll be able to give more specific answers.

Looby