Does anyone know how Tarm makes those water heat storage systems?

[joshuaviktor]

Long story short, I am thinking how to hook up my (future) wood stove to my hot water heating system. Yeah, a good stove will have a hot water coil in it, true. But I was thinking that a bit of plumbing into a tank, with an independant pump, a blow off valve on the tank, (and probably on the coil), and a heat exchanger in the tank hooked to my existing hot water system. Diagram attached as PNG file. It's pretty crude, please forgive.

That tank in the middle needs to be well insulated, hot water resistant. Can it be plastic? Like those 300 gallon tanks they use for power washing trucks?

Anybody know?

 

[Sundeep Arole]

The tarm tanks are made of some rubber lined membrane, I think.

I'll take a shot at this - I have no experience with this, as I don't have such a setup. But here is what I learned when I researched this issue to try it myself.

As far as modifying a woodstove to hook up a hot water coil, there have been several threads on this - all with the general consensus that doing so is a bad idea. For one, the modern non-cat woodstoves
have a heavily insulated firebox, and rely on a high operating temp to generate their secondary burn. Lower the temprature by running water through a coil, and the stove just won't work well.

But - if you are planing to do this anyways - You don't need a tarm like tank for this, a large water heater will work just as well. A indirect fired water heater can be hooked up ideally for this job. You do have
to take care that the plumbing incorporates a T&P valve for safety, and also a way to make sure that the water in the tank doesn't lose heat to the stove when the stove is not running.

Then is the issue of expectations - if you expect the woodstove to provide enough hot water for hydronic heating of the entire house - that is going to be tough, if not impossible. You can however, expect a
decent supply of DHW, though.

If you are serious about going all wood for DHW and heating - then your best bet is to get a TARM with a storage tank. You can get a add-on model which will work in conjunction with your existing boiler, or
a multi fuel unit which will work standalone (and reqire only one chimney), plus auto switch between wood and either oil and/or gas whan the wood system is not able to keep up.