Yes Into The Storm
Wood stove water heaters
An alternative energy option, is to adapt an existing
wood stove to heat household water. A stainless steel
coil is installed inside the stove. Because the coil is
stainless steel, it exceeds EPA requirements for
drinkable water. To install inside the firebox, a hole
saw is used to drill two holes for the ends of the coil
(inlet and outlet). The coil can be plumbed directly to
a preexisting hot water tank. No special holding tanks
are required. When the wood stove is not being used,
flip a switch, and the water heater takes over.
If the existing hot water tank is located higher than
the stove, hot water can circulate by natural
convection. For this setup, the only additional
fittings may be a one-way check valve in the line, and
one temperature/pressure relief valve at the hot water
tank.
If instead the hot water tank is located distant from,
or below the level of, the stove, an additional relief
valve should be used near the point where the hot water
line attaches to the coil, and a circulating pump
should be installed along the cold water line leading
to the coil.
In both cases, cold water is taken from the drain valve
near the bottom of the tank, and the hot water returns
through a tee at the top of the tank.
Since the water continuously circulates through the
stove, it will get just as hot as electrically heated
water. If the stove burns extremely hot, like a coal
stove, there are quite a few different ways to "cool
down" the hot water. One of the simplest is to install
an in-line, variable speed circulating pump. The faster
the water circulates, the "cooler" it will be.
