Masonry Heater with heat exchanger?

No, but looking forward to seeing what you come up with.

DougA said:

Another thought was putting copper pipe in the gap between the refractory brick and the outer stone wall to pre-heat hot water. I know that will cut down on the heat going to the house but there is a small area in my design where I can't help but build against a wall and I would rather put that heat to some use than waste it going nowhere.

Just thinking and would appreciate thoughts from others.

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I know they make the coils that are built right into the firebox. I saw them on EBAY for something like $300. But I looked and there aren't any for sale now. This concept of heating water with a MH is becoming popular. When I asked an Alaskan masonry heater builder about coils, he said this is becoming common, and that he is building more heaters with coils than without coils. But he is in Alaska where houses are more commonly off-the-grid so this makes more sense.

Like you said, you are giving up heat to the water. I guess you'ld just overbuild the MH - that is make it bigger than needed so that it can heat the house and the water, too. I guess you don't need pumps because the water will move itself naturally. I think the modern day German made kachelofens have coils and electronics installed.

My MH is going to be larger than needed for the well insulated house I'm building. It is okay to oversize it if you've got enough materials - and I do. If you want less heat, don't fire it as often, and/or reduce the firewood loads (a large mass at a lower temp heat output = a smaller mass at a higher temp heat output).

And the MH is next to a wall with the bathroom on the other side. And there is an unused space available where I could stick a tank. I should install coils and a tank. I guess it isn't that difficult, but I would need to see it done before I attempted it.

I had never tried out this thing!

alex14 said:

I had never tried out this thing!

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Someday wood stove technology and masonry heater technology will start blurring. The result will be an inexpensive, heavy device that does both convection and radiant heat well, and heats water too - probably built by Woodstock or imported from Germany.

Even now the concept of thermal mass is starting to be incorporated into wood stoves with fire bricks and soapstone. Baffling systems are akin to small flue channels (masonry heater technology).

Why do those darn Germans have to out engineer everybody else? They are building metal fire boxed masonry heaters. They are following the subtle look format by making their kachelofens stuccoed to blend in with the stuccoed walls. So sometimes you can't really see a masonry heater - all you see is a glass door (how deceptive!).

And they are putting water coils in their 'ofens', and electronic brains to control things. Please no - they are heating water with their 'ofen' and with thermal solar panels and running radiant heat coils through the thermal mass floor (thus heating the floor), and it is all electronically brained together - and this isn't that unusual.

And Austrians are starting to build fireboxes with air gaps in the firebrick so air can enter the firebox burn from 360 degrees - causing a more complete burn. Hopefully, this will start catching on in North America.

byQ said:

And Austrians are starting to build fireboxes with air gaps in the firebrick so air can enter the firebox burn from 360 degrees - causing a more complete burn. Hopefully, this will start catching on in North America.

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A gasifier technique. That is another current trend.