Here are my ideas for a HVAC system that would be the most reliable and effiecent way to heat and cool your home, as well as heat your water. tell me what you think or what would be better. Average home design: 1000 gallon water storage tank. Install 100' copper heat exchanger for heating domestic hot water and a 100' copper heat exchanger for infloor heat. the solar system would be a open loop drain back sytem and the tank would be maintained at a minimum temperature with a water to water geothermal unit, (open or closed loop). A water to air geothermal unit would be used to cool the house but obviously it could be used to heat the home as well, (maybe for back up heat being the in floor heat is more efficient and comfortable. I'm thinking a 2 stage water to air system to take care of humidity problems on these super tight homes. A mixing valve would have to be added for the in floor loop beings the tank temperature would range from 140 dagree to 180 dagrees. The only thing I can think of more efficient is a chiller system that uses solar heat , but those systems usually have to be a minimum of 5 tons.

Just curious -- what is your envelope for the walls and roof?

I think he's speaking in the theoretical, however the best money is put into the building envelope.

This sounds quite complex, perhaps past the point of diminishing returns. How many tons of cooling and how much heat would be needed to justify the cost & complexity? A ground-source with desuperheater for hot water is pretty efficient as is.

i agree - best money is in the envelope -- they you buy less geo and less solar etc. This is how geo and solar will become mainstream.