Q&A hot water from a wood stove?

QandA Posted By QandA, Oct 5, 2001 at 2:20 PM

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  1. QandA

    New Member 2.
    Staff Member

    Nov 27, 2012

    Hello-- I have been heating with a woodstove for 3 years, and would like to hook my hot water tank up to it. I know it can be done, and systems are designed for recirculation and pressure relief, but it seems to be difficult to find information on the topic. Can you direct me to good sources of information on how to hook up my hot water system to my wood stove?


    I don't know of any information on the net that details this process, but I do have some experience from my days as an installer. There are two different types of heat exchangers that can be used to accomplish such a task:
    1. External Heat exchangers - if the stove has a large flat surface on the rear, then a serpentine can be fabricates that goes against the rear. If it is enclosed with a layer of sheet metal behind this coil, it will provide better heat. I've had them custom made..but the same shops that make DHW coils (tankless heater) for hot water boilers. These coils were made from a finned copper (usually 3/4"), so much the better for heat exchange. You could make your own by using 189 degree copper bends, but use high-temp (silver) solder so the coils don't come apart if they ever hit a very high tem...which would only happen if they ran out of water and their stove was VERY hot. Input would be into the bottom of the coil, and output from the top. A pressure relief valve should be installed next to the coil...WITH NO VALVES BETWEEN THIS PR VALVE AND THE COIL.
    2. Internal Heat Exchangers - A few companies make such an item, although it may not be easy to find. The best ones are tanks or coil made of stainless steel. The kits come with instructions and a pressure relief valve.
    In most installations a pump and control will be needed. The only exception is when the unit is close to a tank and can be set up for a thermosyphon loop. I used 1/100 HP brass circulators (available from Graingers) along with an aquastat to make the pump turn off and on when the water at the top of the coil heated and cooled. I usually set on at 140 degrees. This then circulated back to the hot water storage tank.

    an article about this at the link below:

    Link: Article Link
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