Print

[mrmopar22]

I am running hot water up to the second floor to eliminate some accessive forced air heat runs.  I have looked at heat exchangers http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200358285242&ssPageName=STRK:MEWAX:IT on ebay, but I think they are pretty expensive.  I had thought about a 3/4" copper pipe inside of an 1 1/2" 10' long, what kind of btu exchange would that give me? Does this work?  I've seen it done, but didn't know how well it worked.

[juddspaintballs]

It does work, but it works better if the inner copper is rolled or finned for better heat transfer. 

This is the one I have heating my domestic water:
http://cgi.ebay.com/SIDE-ARM-HEAT-EXCHANGER-OUTDOOR-WOOD-FURNACE-BOILER-/390278316321?pt=LH_DefaultDomain_0&hash=item5ade668121



Why not use a plate heat exchanger rather than a shell and tube or regular sidearm exchanger? 

[juddspaintballs]

Here's another sidearm exchanger that has a high heat transfer rate
http://www.outdoorfurnacesupply.com/side-heat-exchanger-sweat-p-88.html

[RSI]

Is there a reason you are looking at stainless shell and tube type instead of flat plate type?
I think I could get you a 24" long sidearm like the one in the above post for the same price.