home made water to water exchanger

[william65]

i have made in the past an exchanger with copper tube in a pipe to heat my domestic hot water and it worked great, but now I need to make another and the price of copper is quite high. I was wondering (as i have a few water to air exchangers on hand ) if I could make a small tank and put one of these water to air exchangers in it and run my furnace water through the rad and my floor heat water (glycol mix) in the tank and use it as a water to water exchanger?

 

[ABMax24]

I'm sure you could make it work, but depending on what material you build the tank from it might not be cheap either.

Personally I'd just run one of these, lots of options under $200.

 

[william65]

I'm sure you could make it work, but depending on what material you build the tank from it might not be cheap either.

Personally I'd just run one of these, lots of options under $200.

View attachment 294398

I don't have much knowledge on gpm of these things perhaps I can give you more info and you could steer me to the proper size?

I will have 4 zones consisting of 4 loops in each zone. Loops are 1/2 inch pex 250 feet long each
so i would have 16 loops, all 1/2 pex in cement 3 zones in a basement and one zone in a garage slab

if it ever happened all were calling for heat at one time I am guessing that would be around 20 gpm (some return water and some furnace water) if I guess on the high side and say I may need the exchanger to push 40 percent of the loops water through the exchanger that would be 8 gpm of in floor water entering at 90 degrees and needing to be heated to 160 (these are guesses as well) that would be around 34,000 btu an hour

I am thinking I would need an exchanger that could move 8 to 10 gpm ? Am I on the right track? What size of exchanger would I need to move that much water?

My OWB runs 160 to 180

Thanks for any thought you can pass along