Circuits? what would you add? how many is too many?


New Member
Jul 8, 2020
Helping Dad figure out a boiler system for his retirement home. He definitely wants wood heat. preferably an indoor boiler.

My house is hot water heat from LP
I've got upstairs, downstairs and indirect hot water for circuits.

For the new place I was thinking drastically more circuits:
possibly an indirect hot water tank
green house
apron in front of garage to melt ice(may never get used, but easier to install it and not need it...)
hot tub
possibly even a circuit for the central stone chimney

does anyone make thermal storage tanks larger than indirect hot water tanks?


Minister of Fire
Feb 13, 2012
Central Wi.
Yes, all of the above is possible. depending on what you want to do, larger tanks can be fabricated or purchased. another option is a boiler that doesn't need external buffer tanks. they're kind of disregarded here, but depending on the application, they can be easier to install and put in a dedicated space or outdoors.
I sell and install this equipment, so I'm not going to say brands here. but a couple of clicks can get you to options. system design gets easier when you have 180 degree water available all the time, rather than having to design a system to work with varying water temperatures that are present in storage based systems.

hope that helps.


Minister of Fire
Jul 11, 2008
Northern NH
The current approach is to run room by room individual home run circuits run from a common header using low temperature radiant emitters to maximize effective storage volume. The individual emitters can either be zoned or can be controlled with a local thermostat. Storage volume is only storage until the point where the emitter cant support it. Typical slant fin is typically designed for 140 °F minimum temp to 180 °F max temp. Put in low temp emitters that will heat with 100 °F minimum and it will effectively double the storage capacity. There is also progress being made on air source and small geothermal, both are more efficient with low temp emitters (120 °F is a typical max temp.

If you go with gravity storage, American Solar Technics can make any size tank you want. He is member on this site. The tanks come in foam blocks that are assembled like legos and then screwed together so they can go through a normal door and be assembled in place. They are square or rectangular so they take up less space. The are made out of foam so they are already insulated. Pressurized tanks tend to be standard cylindrical size and need access to insulate. They take up more room for a given volume.

Here is link to free on line course on biomass heating given by the generally recognized number one expert on biomass heating in the US
I have taken his paid course in the past and its gets into more detail but the free one should give you lots of ideas and the price is right.