well we are finally in our new house. its a 1640 sq ft bungalow, with ICF basement, 8 inch walls, good windows, lots of insulation. our initial plan was for a 4 or 4.5 ton forced air unit, changed to a 3-ton forced air and a 2 ton water-water. the water unit will heat the basement floor, garage floor. both have 2" polystyrene under them. i want to set up a 3rd zone, my hot water storage tank. currently for forced air unit has a desuperheater and will meet most of my hot water needs in the winter months, and possibly in the hottest period of the summer. i want to use my water to water to maintain a minimum tempurature in my tank during the rest of the year, as the hot water output of my storage tank goes to the cold water intake of a 29KW instant hot water heater. i want to minimize the amount i actually use thispower thirsty unit. the problem is, my water to water unit will need to circulate antifreeze as my garage floor can and probaby will freeze. so i bought a brazed stainless steel and copper flat plate heat exchanger. it has 30 plates and is 12" x 5" .  looking at the spec sheet it looks like this thing has plenty of btu capacity, however my geo installer is concerned that it doesnt. anybody have any experience with these?

Hedgehog,

Did I understand your post correctly?  Are you using a single wall heat exchanger between potable water and the antifreeze?  Are you using food grade anti-freeze?

 

yes this a single wall heat exchanger, and if required i suppose i can use a foodgrade antifreeze. also the fresh water side of the heat exchanger will be pressurized to what ever our city water pressure is, the heating side will have very minimal pressure.