Hi, I have hooked up a thermosiphon system to my wood stove. I haven't got it to operating temperature yet, partly because the wood stove with loop inside is what we use to heat house and it isn't cold enough yet to have wood stove running constantly. I have a twice run the stove with just one stove full of wood to bring house up to room temperature and aside from the tank gurgling a bit during the heat cycle all was good as far as I know.
The upper pipe got very hot and the tank temp got to 90 degrees F according to temp gauge installed and pressure never exceeded 50psi (pressure pump psi) according to gauge installed in system. Then the 3rd time I ran a stove full of wood I was getting severe banging in the tank several times above the gurgling. Water temp reached just over 100 F this time (one extra piece of wood this time).
From a bit of research, it might be thermo shock?
Here are the details of system. I have a new 50 gallon electric water heater as the tank and left the factory elements in tank. The wood stove is not very big, enough to heat about 1100 sq feet. I installed a 1" stainless steel loop in stove. Behind wood stove is a wall and on the other side offset about 3 feet is the water tank elevate about 3ft off floor and the cold water out from tank is about 1ft higher than hot water line going into wood stove, so lowest port of water tank is about a foot higher than highest port on wood stove.
I ran 3/4 type K (thicker wall) copper pipe for both inlet and outlet water lines. The upper pipe (hot) from wood stove comes out of back of stove about 6" to a 45 elbow, then 4" straight pipe to another 45 elbow, then 4 inches to a ball valve, 4" more straight pipe to a 90 elbow up, about 10" straight pipe and a 90 elbow through wall, about 8" straight pipe through wall to a 45 elbow up, then about 2ft straight pipe to another 45 up which is just a few inches off the tank, from that 45 it goes up tank about 2.5ft to a 45 elbow, about 4 inches straight pipe to another 45 elbow and into top center of tank where the T&P valve was from factory (T&P valve is relocated). All hot water line out of wood stove has at least a 1/4 per foot rise in horizontal piping.
The cold water line out of tank to wood stove has more 90 and at least a 1/4 per foot drop in horizontal lines going to wood stove.
On top of the tank I have also the two factory cold and hot water connections. The cold water connection coming in has a tee and an expansion tank above tank right below ceiling.
The hot water out to house has a 3/4 cross on tank connection. on left side of cross is the temperature gauge. On the right side of cross is a tee. One the left side of tee is the pressure gauge. Out of the top of tee is the hot output to house which also has a tee with a air vent which I opened during the cycle I heard the noise (possible thermo shock) and there wasn't air just water coming out. Out of the top of the cross is the T&P valve piped to drain.
It appears that the concept is working as the top pipe coming out of wood stove gets extremely hot and tank temp has raises from room temp 72F to just over 100F in about an hour and I see no problem getting hotter running stove longer when it is cold enough to warrant running stove continuous, but what is that noise and is the gurgling normal?
I have read that maybe the water is cycling too fast and the hot water going into tank is too hot when it mixes with cold and thus could be the problem. It was suggested that I throttle the valves a little at a time to slow the water movement. I do have a valve on both hot and cold lines between wood stove and where pipes go through wall as well as a bypass valve in between both so I could close both hot and cold lines going into wood stove and open bypass to remove wood stove from system in summer should I need to.
Any help in solving this would be greatly appreciated.....thanks
I can add pictures as well if that is preferred, might be easier to understand and visualize plumbing.
