<div dir="ltr"><br><div class="gmail_extra">Hi,</div><div class="gmail_extra">Maybe you are already aware of this, but there are coils that fit inside the fire box:</div><div class="gmail_extra"><a href="http://www.hilkoil.com/product.htm">http://www.hilkoil.com/product.htm</a></div>
<div class="gmail_extra"><br></div><div class="gmail_extra"><br></div><div class="gmail_extra">You do have to be very careful to have pressure/temperature relief valves at the right points in the plumbing with these to avoid steam explosions:</div>
<div class="gmail_extra"><a href="http://www.builditsolar.com/Projects/BioFuel/biofuels.htm#FireboxCoils">http://www.builditsolar.com/Projects/BioFuel/biofuels.htm#FireboxCoils</a></div><div class="gmail_extra"><br></div>
<div class="gmail_extra">Seems like this would be a more efficient water heater and reduce the chance of cooling the flue gases too much?</div><div class="gmail_extra"><br></div><div class="gmail_extra">Gary</div><div class="gmail_extra">
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