SS loop heat xchgr for woodstove

Drake · 02-12-11, 11:12 AM

Would like to add manual wood heat capability to hydronic radiant heat system I plan to put in rural home(back up for elec outages or severe cold spell). Seen SS pipe loops that can be refit in woodstove. This in a small stove could heat water(low demand needed) and give space heat but $100+ prices seem pretty high for a bent SS pipe. Can something similar be made or found cheaper? Maybe one with threaded bends and welded? Bronze pipe, brazed?

Ryland · 02-13-11, 09:45 AM

To make a U shaped tube out of 3/4" stainless steel pipe is going to cost you $30 each for 2 foot long chunks of pipe and about $10 each for 90 degree elbos, mcmaster-car doesn't have chunks shorter then 18" so another $22 for that and you are up over $100 before shipping.
So yes, you can make one, but $100 for a single piece of bent pipe sounds like a pretty good deal because your other option is to buy a straight piece of pipe and pay someone to bend it for you and again you are up to almost $100.

Drake · 02-13-11, 10:55 AM

As the "stove" I plan to use needs no aesthetic appeal I am thinking two(maybe three) 1/2" straight pieces of SS run thru stove and manifolded together outside stove on opposite sides. I thought on how close soldiered unions could be? Silver soldier better? High temp joint compound for threaded joints? Can't see the difficult/expensive "U" functionally needed. SS pipe run $5-7 locally, can self thread. Will need to be sure I don't restrict thermosyphon flow.

Ryland · 02-13-11, 02:33 PM

If you can get the joints outside of the fire box then you will have a much easier time, at that point you could even use galvanized fittings, you just don't want to have galvanized steel inside the fire box as it will burn off and is pretty nasty when that happens, you could at that point also use silver or copper never seize on the threads to get a tight fit and seal, the copper never seize I have is good up to 1,800F so not good again if you want it in the fire box but outside the fire box it's just fine.

02-12-11, 11:12 AM	#1
Drake DIY Guy Join Date: Jan 2011 Location: Mpls,MN Posts: 315 Thanks: 2 Thanked 17 Times in 17 Posts	SS loop heat xchgr for woodstove Would like to add manual wood heat capability to hydronic radiant heat system I plan to put in rural home(back up for elec outages or severe cold spell). Seen SS pipe loops that can be refit in woodstove. This in a small stove could heat water(low demand needed) and give space heat but $100+ prices seem pretty high for a bent SS pipe. Can something similar be made or found cheaper? Maybe one with threaded bends and welded? Bronze pipe, brazed?

02-13-11, 09:45 AM	#2
Ryland Master EcoRenovator Join Date: Mar 2009 Location: Western Wisconsin. Posts: 913 Thanks: 127 Thanked 82 Times in 71 Posts	To make a U shaped tube out of 3/4" stainless steel pipe is going to cost you $30 each for 2 foot long chunks of pipe and about $10 each for 90 degree elbos, mcmaster-car doesn't have chunks shorter then 18" so another $22 for that and you are up over $100 before shipping. So yes, you can make one, but $100 for a single piece of bent pipe sounds like a pretty good deal because your other option is to buy a straight piece of pipe and pay someone to bend it for you and again you are up to almost $100. Last edited by Ryland; 02-13-11 at 09:48 AM..

02-13-11, 10:55 AM	#3
Drake DIY Guy Join Date: Jan 2011 Location: Mpls,MN Posts: 315 Thanks: 2 Thanked 17 Times in 17 Posts	As the "stove" I plan to use needs no aesthetic appeal I am thinking two(maybe three) 1/2" straight pieces of SS run thru stove and manifolded together outside stove on opposite sides. I thought on how close soldiered unions could be? Silver soldier better? High temp joint compound for threaded joints? Can't see the difficult/expensive "U" functionally needed. SS pipe run $5-7 locally, can self thread. Will need to be sure I don't restrict thermosyphon flow.

02-13-11, 02:33 PM	#4
Ryland Master EcoRenovator Join Date: Mar 2009 Location: Western Wisconsin. Posts: 913 Thanks: 127 Thanked 82 Times in 71 Posts	If you can get the joints outside of the fire box then you will have a much easier time, at that point you could even use galvanized fittings, you just don't want to have galvanized steel inside the fire box as it will burn off and is pretty nasty when that happens, you could at that point also use silver or copper never seize on the threads to get a tight fit and seal, the copper never seize I have is good up to 1,800F so not good again if you want it in the fire box but outside the fire box it's just fine.