View Full Version : Hot water from wood stove

Karl White
11-01-2008, 03:09 AM
I would like to comment on obtaining hot water from a wood stove and my experience doing it. I have an Atlanta box stove with a coil in it hooked to a 50 gallon indirect hot water tank. I have used this system for 11 years and it works perfectly. I used thick walled brass pipe inside the stove and ran 22 inches of pipe on the side above the fire brick. Outside the stove I used copper to connect it to the water heater. It has an automatic fill, pressure guage, expansion tank and blow-off valve. No circulator needed as the loop circulates by itself. I also have a mixing valve for DHW. I have no excess creosote in the chimney, the smoke pipe & chimney are checked often and cleaned once a year.

The success of the system is relevant to the coil length. I experimented in the beginning by making a coil to long and way to much hot water was made. Adjusted the length twice to get the 22 inches. On the coldest days of the winter I can run the stove at maximum output without any problems.

I run the stove 8 months of the year and figure I save about 40 to 60 dollars a month using wood instead of electric or oil. It has paid for itself numerous times over and it is so nice to take a hot shower knowing where the water was heated from!

11-01-2008, 06:43 AM
I work with a man who has a wood stove heating his entire house via hydronics, and he has been looking into adding something alongside the stove to connect to a water heater with an internal heat exchanger. He says his brother already has a system like that (similar to yours) working well and trouble-free.

11-01-2008, 08:02 AM
If something heinous were to happen would your insurance cover it?

11-01-2008, 08:12 AM
NH Master...
There is a little guy with a thermometer that runs the damper...
He's all the controls you need...:D

11-01-2008, 03:43 PM

11-02-2008, 02:16 PM
The above way is how it was done before the units we have now, which became common place. As the OP stated, there is a PRV it sounds like, so no problems there.

11-02-2008, 03:07 PM
How do you control the temp of the water. How do you shut it down when you reach 110 or 120 in the tank?

11-02-2008, 03:35 PM
A lot of safety controls are missing on this hacked up mess we are talking about...

11-03-2008, 11:04 AM
You would let the fire die down to the point where it is controlled. Otherwise, would have to mix in cold to the tank.

Karl White
11-14-2008, 01:32 AM
How do you control the temp of the water. How do you shut it down when you reach 110 or 120 in the tank?

The hot water is used daily for showers, dishwasher, cooking etc. The water temp is never higher than 130 deg and the mixing valve tempers it to 120. When the stove is banked for the night it's the best time for making hot water. The T&P has never blown off and I have it piped to the outside if it ever did. On cold starts it takes about 24 hours to bring the water up to temperature.

Sorry I didn't reply sooner, I just returned from vacation