Hot water from pellet stove?

[Albert]

We've had a Whitfield stove for 15 years, very happy w/its performance, etc. Built a very efficient small house with good solar orientation, etc, have some passive solar stuff going on and have been thinking lately about winding a flexible 1/2" copper coil around my 4" flue, plumbing it through the holding tank I use for my small passive batch h20 heater that I use from April to Nov, and there by preheating my DHW. I've been keeping track of my flue temps and they're generally around 150-220 degrees F. I think this should be hot enough...the linear length of the coil is about 24". Question is: Is the temp high enough? and is the exposed area to that heat enough to get any usable transfer of heat to the water?

 

[drizler]

No specifics for you but I would think it to operate like a grey water pre warmer used to raise the temp of incoming water before the boiler using water from showers and dishwashing ect. I think they called it a booster. Somewhere someone had a complete pictorial of the rig and it worked well for raising the temp somewhat which is all you are going to get anyways right? Every little bit helps I guess. At least with such a low heat output you wouldn't have to worry about boiling the water and causing an explosion since it just doesn't get hot enough. You would do better covering it all with a layer of insulation to keep the heat concentrated as best you can. Probably wouldn't look too pretty. I imagine it would work nicely by natural convection if you can manage to get the heating tank higher than where you have the coils. I imagine you could look at the build it solar website and incorporate the principals of their solar ideas for the preparation, sizing and materials involved. I have thought about doing something similar myself some time but like lots of things just haven't gotten their yet.