I am considering building with 3 geo systems. Due to house layout, it isn't easy to get duct work to one side of the house. There isn't enough crawl space to run all the required ducts. One system is upstairs and two are downstairs. Assuming I am stuck with three systems - is there a best known method for installing a DSW system with multiple systems? I know a buffer tank is required for best performance. Does one pick the most frequently used geo system and use that one? Or is there a way to benefit from all three? I am guessing the system that gets the most use would differ between summer and winter. I am in a cooling dominated climate.

Hard to say over the internet. One can (should, actually) use checkvalves to keep DSH water from backflowing through a dormant unit.

Consider also split systems where the compressors are in one place but air handlers elsewhere, but don't let DSH considerations drive that decision. Splits allow greater installation flexibility and potentially quieter operation, but there is an efficiency penalty and installation may be more complex owing to the need to run refrigerant gas lines

You may want to investigate zoning - it may be cheaper to zone a single large system rather than buying and installing two smaller ones. The cost increment per ton plus zoning is so much less than the cost of 2 separate units. Adding an extra ton to a unit adds only 10 or so percent to the price

Hi aus,

I recently asked a similar question here:

Climatemaster Tranquility 27 - one 4ton versus two 2ton?

Thanks. I just noticed the DSW part of that thread. Seams it is just fine to have 3 DSH hookups w/ check valves.

Existing construction, so I don't have a good (inexpensive) way to change the ducting and go with 2 systems and zone one of them.