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Schematic of combined Gas/Solid fuel CH system, Help?

Discussion in 'Plumbing and Central Heating' started by carryoncamping, 3 Dec 2013.

  1. carryoncamping

    carryoncamping

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    Location:
    Yorkshire
    Country:
    United Kingdom
    I'd be grateful if anyone could comment on a schematic diagram I've drawn up of my existing 'Gas Gravity fed / pumped CH boiler' (on left of diagram) combined with a future solid fuel back boiler (on Right of diagram).

    http://www.diynot.com/network/carryoncamping/albums/18674/69910
    http://www.flickr.com/photos/44875755@N02/11209804173/
    Current set up:
    12 kW Gas boiler Gravity fed HW and pumped CH
    Dunsley 5kW Wood Burning Stove, (fed on a free supply of wood).
    Solar Thermal system heats domestic HW 6 months of the year (not shown on diagram).

    Note: Hardly ever use the Gas boiler as our house is VERY well insulated and the 5KW stove does most of the heating. (e.g. gas bill last year <£100)

    As part of our home improvements (of which local Building control have been notified) we are toying with the idea of installing a back boiler in the Stove.

    It is ONLY 2KW and would be mainly to heat the water in the 200l cylinder during the darker months when the solar thermal is less effective.

    I have combined the two systems with a plate heat exchanger. I am aware of the Dunsley Neutraliser but not quite sure how that would be more effective in the current setup?


    My thermal calculation for time needed to heat 200 litre HW cylinder from cold by 2kW back boiler (assuming a constant 2kW) are as follows:

    Water vol=200litres
    Water SHC =4.2 kJ/kgC
    DeltaT = (60-10)=50C

    Time required for 200 litre cylinder to reach 60C from a cold start would be:

    =200*4.2*50/2/3600 hrs
    =5.8 hrs

    My fire is typically lit for 10-12 hours a day so I have an excess of hot water which could in theory feed the 2 radiators (3400BTU/1KWh) I have/use.

    Your time and thoughts are very much appreciated on this topic.

    PS
    I can email a higher res diagram if anyone is interested.
     
  2. carryoncamping

    carryoncamping

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  4. carryoncamping

    carryoncamping

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    Location:
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    Anyone willing to take a look at the schematic of my combined gas/solid fuel |HW/CH system?

    I'd be grateful for any tips.
     
  5. Norcon

    Norcon

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    As the boiler is only 2kw you need to dispense with the load valve and any interlink connections with the gas boiler.

    Injector T also not needed as you only need to set this up as a gravity circuit.
    Only thing I would add is an avta cooling valve on the gravity rad to give the cylinder priority.

    Pipes should connect to the gravity rad without any valves.
     
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