Need water block to pull heat from wood stove

[CarlUman]

Was not sure where to put this but figured if anyone had an idea you all in this forum would.

I'm looking for a waterblock for my wood stove. Basically a chuck of metal with a hole through it so that I can attach it to the front of my wood stove in the garage to heat some water as it passes through. I'm losing a lot of heat off the front of that stove and my garage is always over 65 when the wood stove is running so I'm thinking this would be the best way to get more heat out of the stove since I'm already pushing the hot air through a water based heat exchanger.

Best thing would be a solid block about 1-1.5" thick and 8" x 20" or so in size with 3 or 4 water lines in it to run parallel but individual blocks would work also.

Any ideas where I can find such a thing or do I need to visit a metal shop?

Thanks
Carl [img]/forums/images/icons/wink.gif[/img]

[GaryM]

How about some copper tubing that would zig-zag back and forth across the front of the stove. Then go on to the heat exchanger. You could solder it up yourself, or use soft copper tube and just bend it out of one piece.

[egon]

Soldering may be in temperature trouble depending on where the joints are.

Years ago many cook stoves had a cast iron water block that sat right inside the firebox.

I have heard of people putting stainless steel coils on the back of airtight stoves for heating.

Just remember water can be turned to steam quite easily so some sort of safety pressure relief and ways of keeping the tubes full of water will have to used.

Egon [img]/forums/images/icons/grin.gif[/img]

[GaryM]

Egon, You're right about the solder being a possible trouble spot. That's why I mentioned soft tubing so no joints would be requried. Alternativly, the joints could be brazed rather than soldered.

Good point about the steam. Need a relief valve and a feed pump too.

[CarlUman]

I've thought about the soft copper but there isn't enough area for contact on a round pipe to transfer the heat... even if I smashed the copper to have a flat side it wouldn't be flat enough to make good contact. At least I don't think there is but it might be what I end up trying.

A tank and presure valve are already part of the system. So far my max temp is 150 and that is using only one of the two heat exchangers inside the house and a really hot fire. Noarmal temp is around 100 [img]/forums/images/icons/frown.gif[/img]

[GaryM]

OK, how about a copper coil in the flue, just where it exits from the firebox? If the space is available the coil could be a few inches across and a foot or two in length. Depending on flue configuration of course. Corrosion of the copper from flue gases might be an issue. I don't know about that part.

How about copper soft tubing, or hard tubing with braised joints, adheared to a copper sheet. The tubing could be braised to the sheet. Is refractory cement heat conductive or heat insulating? If conducting, sandwich the tubing between two copper sheets with refactory cement filling the space not occupied by copper tubing.

Just trying to imagine solutions not requiring any machining operations. [img]/forums/images/icons/smile.gif[/img]

[CarlUman]

I'll have to think on that one... sounds like it could work [img]/forums/images/icons/smile.gif[/img]