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Wannabe Geek

Topic # 191422 3-Feb-2016 18:54
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My first post, hello everybody. Have just purchased a doer upper in the BOP and first up is the heating - need to get something set up for winter.




Currently has a woodburner with wetback, directly heating the HWC. Low pressure, open vented, no pump, works perfect.




It is my wish to add 2 or 3 radiators to this system, but as it is direct (no heat exchanger in the HWC) i am faced with the challenge of keeping the two mediums separate, as i do not wish to drink radiator water!


current ideas are:


an extra wetback coil in the wood burner and independent radiator circuit




heating either the radiator circuit or the HWC indirectly, with a heat exchanger. The easiest solution for me would be to send the water from the wetaback to a heat exchanger and one heat sink rad, and pipe the domestic hot water around the heat exchanger to heat it up. Would this work? i could then possibly add another 2 radiators on a pumped circuit etc etc.


My main question is, would the heat exchanger and heatsink rad from the wetback be enough to heat the hot water, and what type of heat exchanger should i aim for?




I am aware of having to open vent the new circuit and include a header tank etc etc





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  Reply # 1484729 3-Feb-2016 19:30
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How many kW output is your wetback? No point bothering if it is only a 1kW output one.




Best system would be a combined water circuit for the wetback and radiators. With the cylinder water separate. Would be expensive as you will need a custom heat exchanger, 2 pumps, suitable controls. But will give you best flexibility, allow cylinder temp to be regulated, and you will be able to convert to a mains pressure wetback system if you replace the hot water cylinder. (using an off the shelf cylinder instead of a wetback one as well).




Cheaper systems will have controllability issues. and no upgrade path to mains pressure hot water.




Also have you considered a heat transfer system? (ducting from lounge to bedrooms, with a thermostat to switch fan on when lounge is warm).




And the biggest question - does the system need to fully comply with council rules?

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