DIY Projects: Stainless Flue Hot Water Heating

Stainless Flue Hot Water Heating

In the early days here, one of the first things that we did was we decommissioned the two central gas-fired heating systems. Now, because we live in the countryside, it was LPG. It was really expensive to run and not very helpful because the heating simply came out from the ceiling outlets, which is not ideal.

We got rid of the LPG tank and we stopped using the heating systems. The wood-fire became our main heating source. Now if you’re going to use a wood fire to heat hot water, normally there’s a water jacket built into the wood-fire, but this one was new and it didn’t have water jackets. We decided to add a wet flue. The bottom section of flue here is a stainless steel jacket and the pipes at the back lead up into the hot water tank, which is just
above it.

You run the fire to heat the living room. The fire heats up the flue, the flue heats the water up and it’s a simple thermosyphon. Again, it goes around and heats up the water in the hot water tank.

If you are thinking of doing this, there’s just one little fault we didn’t do. The pipes are nicely curved going up, but in fact, what that leads to is when the hot water system gets pretty hot, you can have the thermosyphon stagnate and this starts sounding like it’s going to be a bomb that blows up, but eventually it boils, has a bit of a hissy fit and it starts again. This can be prevented if the pipe at the back here actually went down before it went up and that would circumvent that little issue. It’s not really a problem, but it just sounds a bit ominous when it happens.

That’s it. Earlier, we saw that we’ve got the 40 evacuated tubes on the roof in a set of 30 in a set of 10 that feed into the same tank. When the sun’s out, it heats up the hot water. When we’ve got the wood-fire on, which is less so now that we’ve got a couple of really good split systems (they’re just so convenient), and of course wood fire, not really very good environmentally. We use it at a minimum now. So, the wet flue doesn’t actually do very much for us these days, but when we put it in, it was the main source of heating and did a fantastic job of providing hot water as well.

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