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We just got a Chimenea, primarily for patio heating, but I was wondering if anyone has thought about using one to heat water in some way. A lot of heat comes out of the top of the flue and although it has to be used outside I'm sure someone resouceful enough could come up with some sort of system that would run a water pipe over the top or maybe divert off the heat somewhere?

I guess u are right.. u need some sort of water jacket... similar things have been tried with woodburners I understand. In theory simple, but practically speaking - there can be dangers. If your water is heated too much, there can be steam explosions if you haven't designed it properly. Needs engineering input.

if you can get hold of a clean 44gallon drum and some copper pipe:
1. wrap the copper directly around the flue then braze into top and bottom of drum.
2. fill with water and i imagine it would thermo cycle nicely

note: on second thought a smaller vessel might be more practical and more likely to heat to a useful temperature in the given time a Chimeneais likely to be running for

frozenthunderbolt wrote:if you can get hold of a clean 44gallon drum and some copper pipe:
1. wrap the copper directly around the flue then braze into top and bottom of drum.
2. fill with water and i imagine it would thermo cycle nicely

note: on second thought a smaller vessel might be more practical and more likely to heat to a useful temperature in the given time a Chimeneais likely to be running for

...and you could always add a safety valve at the top of the pipe.

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Davy stephenson wrote:As an engineer myself the system that frozen explained is called a flash boiler, these are very temperememntal and need expert knowledge to make and fit to any suitable heat source, which can kill you in a very short time if you are not very careful.

The patio heater is not designed to heat water but the people around it by radiation via the best material pig iron, they are too top heavy once they have a boiler fitted, the wrong design and shape to heat water, I,m not saying it cannot be done.

if you have and open vessel not a presurised vessel and an asending spiral of copper tubing for water to cycle through dont you essentialy have a wetback system? can you give me a little more info on "flash boiling"

If, as frozen says you have an open tank, with an open loop, there should be no problem... no pressure no valves just thermo-syphoning.

This is how my old back boiler/ wet-back worked (now defunct, but that is because we replaced the fire with a wood burner)

I would imagine you could get water warm enough for a bath easily enough.


Having said that, I don't think it would be practical to plumb it into your home system, but if you have the ways and means for a separate tank - in a shed perhaps for outdoor use.

Oh... a shed containing a compost toilet and hot running water... now your talking