Q&A Make boiler from Lopi stove?

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QandA

New Member
Staff member
Nov 27, 2012
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Question:

I am a homeowner with a medium-sized average Lopi woodstove. I installed a custom squirrel blower (low acoustical noise) that gives me quite a lot of hot air through the stove ducts, so it heats the whole upstairs very nicely.

I want to create a hot-water heating system, in which I install a boiler that replaces the first two of the insulated asbestos sections.
This boiler must resemble the chrome-plated insulated chimney I have presently, so that the appearance is normal.

It would probably replace the first two sections, therefore, it would be 6' in length. Are you selling such a custom flu boiler presently? I do not want to merely insert a serpentine tube, since it will not even begin to tap the total BTU's available.



Answer:

Here's the thing - if you have a newer Lopi stove, it has a tested efficiency of approx 70%. If it's an older one, then it could be as low as 50-55%. The maximum efficiency that you could get out of a stove is about 80%, as there always must be some heat to carry the by-products and moisture up the chimney. This means the the potential for reclaimed heat is much lower than your estimate.

A setup like you mention may be OK for getting you some domestic hot water, but it will not provide enough hot water to heat large areas of the home. Consider a modern oil or gas boiler. These appliances fire a flame of 100,000+ BTU into a chamber that can reach 1500 degrees F. They also have 20-50 square feet of heating surface (using boiler firetubes) to extract that heat.

In your stove, the flue temperatures are probably as little as 3-400 degrees, and should not be brought down much lower than this.

Stoves with boilers INSIDE them are popular in Europe, but there are none that I know of currently available here. You can find some nice basement wood boilers at https://www.hearth.com/tarm

Link: HS Tarm Wood Boilers
 
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