Connecting wood boiler

[Quad4012]

Perhaps if you broke out the manual for the boiler you have, it might have some suggestions for domestic hot water. Maybe there are connections on it for that, but you would think the plumber would use them then. I think my sister in law got a Bosch combi boiler that supplies hot water for heating and separate instant hot water personal use.

I was thinking that perhaps I could keep our current boiler for heating only and then add a separate domestic hot water heater. My question is that if I did that how can I also make the outdoor wood boiler serve as a domestic hot water heat source? I guess the other big question is are there any boiler additive treatments out there that are non-toxic? I know this propyleneglycol but that's not a corrosive treatment additive.

 

[maple1]

A somewhat typical OWB install would have the OWB water first go through a DHW heat exchanger (often a sidearm - sometimes a flat plate), then through another heat exchanger for heating system (flat plate). Then back to the OWB. Keeps the OWB water separate, and volume minimized so not as much treatment is needed. And the indoor system side is closed/pressurized - and not really needing treatment.

 

[velvetfoot]

Would there be a tank involved with this plan?

 

[electrathon]

This system is almost identical to one I helped a friend install in his house a few years ago. It worked very well. Yes, the water was mixed. depending on the path the water took it was either floor heat or DHW. DHW does not heat the floor, it ran a different route. I know it worked flawlessly for about two years (he died, unrelated to any of this) so I have lost track of the way it is working. The building and planning inspectors both allowed it to be built. The plumber that was doing the remodel did not understand it, even after I gave him drawings, so my friend and I did the install. Everything in the system was stainless, red brass or Upnor PEX pipe.

 

[electrathon]

Would there be a tank involved with this plan?

There is no tank, they heat water as needed. It is a good idea though to have an expansion tank. If the floor system is holding 30-50 gallons of water there is a lot of water expansion between 50 or so degrees cold to 120 degrees hot, close to a gallon if I remember correctly.