OK, crazy idea. Just throwing it out there.
I have a little wood stove. I love it. However, it is NOT good for a steady heat, especially unattended, and STORING that heat for any amount of time.
Water is a fairly good material to use for storing heat. It's cheap (nearly free!) flexible, moveable, has all sorts of good qualities.
The trouble with water is that it takes up a good amount of space.
I don't have a lot of space. I don't have room to add 55-gallons drums in my living room.
What I do have is a 210 gallon freshwater aquarium.
It happens to have goldfish in it.
It's not heated. I think that electric heat for something like fish is a waste. (Keep in mind these are just pretty carp, and they don't care about their water being cold. If you keep a small tropical fish tank and run a heater all day and it's you one love in life - GOD BLESS YOU!)
SOOOOOO....... What about the potential of using 210 gallons (roughly 1700 lbs) as an absorber of heat from the woodstove?
The aquarium is about 6' long, 30" high, and 24" deep. I would imagine that it would just slowly radiate heat out to the room.
How would the fish feel about it?
I image that goldfish wouldn't mind 80 degree (F) water. Any fish experts here? Being cold-blooded, their metabolism would increase. They would eat more, be more active, grow bigger, and have a shorter life span?
The aquarium is about 10 feet from the woostove. The sofa is between the two. I could run insulated pipes under/behind the sofa to the aquarium. Maybe just a coil of cover pipe poking down under the water of the fish tank as a heat exchanger?
A small pump would push water through the pipes to woodstove, where it would be heated, then back to the aquarium, where the cooler fish tank water would absorb the heat.
Heat builds up in the aquarium, making the water hotter than room air temperature. Late at night and early morning (when the fire is out) the heat from the aquarium would radiate out into room space.
The aquarium already has a thermometer on it to monitor temperature. I could probably figure out a way to automate it, based on temperature, but to start with, just watching the thermometer and modulating how much heat goes into the system should be OK.
What other things do I need to think about. Obviously, I don't want to boil the fish...
Somewhere in here I need pressure relief. That could be taken care of simply by having an additional, open-topped vessel that would allow pressure to escape. (Kinda like in a drain-back system.)
Your thoughts?