Aussies Living Simply

Hydronic Heating

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    In what I can only describe as serendipity, after thinking about hydronic heating (using water heated by a wood fire) for a couple of years, the other day I received some old plumbing text books (1930’s and late 50’s) and last week I scored a bunch of convectors and a gas-fired heater.

    I just wondered whether anyone has had much experience with it and what they thought about it as an alternative to other forms of heating. I’m really trying to get away from electricity and gas and the old books use the natural tendency of hot water to ‘rise’ in order to circulate heated water through the radiators. In Europe it was, and probably still is, very common, especially in large multi-storey buildings. It’s amazing that they could heat several floors just using gravity to circulate the hot water to the top floor.

    Has anyone got a system that works this way without pumps? Would be interested to hear of anyone’s experiences good or bad. I think that some of the old technologies are going to have to be re-learned as the price of energy goes through the roof.


    Hi silentC sorry for not replying earlier, I misread the title and thought it was about something else. I don’t know much about this except for the system that I currently have.

    We have a wood stove that we cook on that also heats our water in winter. I can have the fire every two or three days and the water stays hot enough. We also have the water pumped through black plastic pipes over the roof to heat it in summer. We also have the option of using electricity to heat the water, but I have turned that off at the fuse box a long time ago.

    The bonuses i see are to heat water from a cold start (if you have been away for example) does not take long. If I get the fire hot the water can be heated in under an hour. As mentioned that stays hot for a few days. We use this stove fire to heat the house and to cook, I get most wood on site so it is pretty cheap to run.

    The down sides here may be different to other people as my system is set up to run off a few sources. Having the hot water system in the roof cavity is not great if you need to get in and fix something. Personally I would much prefer a hot water system outside in case of a leak or something. We had to do work on the system not long after moving in and it was troublesome accessing the tank etc.

    We have a small pump to get the hot water from the system to the taps, without this pump the hot water barely trickles. This pump again is in the roof and is trouble to reach when things go wrong. I do not know how much this pump costs to run, you can hear it kick in when a tap is turned on. If the shower head in the bathroom is too high the pump does not kick in, we work around is by pulling the shower head a bit lower. A Plummer looked at this when we had trouble and had no idea why it was happening or how to fix it.

    There are times when the sun is not hot enough to heat the water in the black pipes, yet it is too hot for a fire, this is presumably why they included the option of using electricity here.

    I only know this system so I am not a great source of information on the topic but will try to answer any questions as best I can.


    A lot of what you want to do depends on the house design and layout.

    A wetback stove will have the hot water tank above it for thermosyphoning (unless there’s a pump here for a ground mounted tank). So with your tank up in the air, there’s little chance of doing panel radiators through thermo syphoning unless you have a multi-storey home.

    The place I built back in the 80’s was basically passive solar designed and oriented (which helps dramatically for heating and cooling). As the hot water tank was mounted inside the chimney and above the stove, we needed a pump to circulate the water through the radiators. Worked well while you were up and stoking the fire, but used up all the hot water overnight so no shower in the morning!


    ( Sorry – totally off topic ………I have to go Google mukluks……. :laugh: I didn’t know they are something and often wondered about your name, Mukluk!! )

    (Later! Well, what a surprise ! Not at all what I was expecting!! :laugh: :laugh: )


    Thanks for wandering BlueWren because I somehow missed all the replies above. I always forget to tick the box to be notified of replies.

    I have to get back onto this project soon because winter will be here again before I know it. We need a new fire and I’m planning to get one with a wet back.

    I understand that the normal set up is to have the hot water tank in the roof so that it can thermo-syphon from the wet back. We’d then need a circulation pump to distribute water to the radiators. I’m not even sure that the radiators I have will work with thermo-syphoning. Both connections are at the bottom of the radiator but I assume one goes to the top of the element, so it should work.

    What I was considering was a heating-only system, which simplifies things quite a bit. There would be no storage and the water would just circulate continuously.

    But that might be a waste of potential. We do have the ability to have the boiler on a lower level than the rest of the house, and my longer term plan is to build a family room in underneath the house as we have 3m headroom at one end. So Maybe I could have the best of both worlds by putting the wet back down there, and have the storage tank where it is now – below floor level but a metre above where the wet back would be. Not sure if that would be enough head to get water up into the storage tank though.

    I’ll keep studying the books…



    I grew up in Germany where almost all houses have hydronic heating. It is definitely nothing for DIY.

    The most important thing is the danger of steam explosions. Occassionally people connect something to their woodstove, and if pressure builds up because the are no safety valves even the explosion of a small system will flatten a house. Do not do it – it is only for experts.

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