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Discuss Ground source heat pumps in the Renewable Energy area at UKPlumbersForums.co.uk.

  1. Ians.mckay

    Ians.mckay New Member

    Heat pumps can be a nightmare if not setup correctly the ground water has to be
    The right flow and not too cold I've been to some installations and they didn't have
    A constant flow so the unit cut out on evap flow and it can use massive amounts of
    electricity if just put in and switched on .
     
  2. Spanish

    Spanish GSR

    installed pv on roof 6 years ago, paid itself back and this year my energy costs total will be in the region of £750 but the pv will pay me £1500 so it does work,

    Have just had a few quotes for GSHP and will be going ahead, it is a refurb and the insulation will be over and above current recommendations so the GSHP will pay for itself (if works to 75% of expectation) within the 7 years
     
    Last edited: Apr 1, 2016
  3. quality

    quality Plumber GSR

    This site is mainly hung on natural gas, oil or lpg. there are not many of us who are fitting renewables which is what most gas engineer fear
     
    • Like Like x 1
  4. Sparkgap

    Sparkgap Active Member

    Over the years I've seen some renewable installations which worked pretty well and many others which were completely pants. Some retrofit jobs should never have been taken off the drawing board and end up costing a sight more to run and install than equivalent oil/lpg. I've also found not all major contractors/consultants are clued up on them either so going to the big boys doesn't always equate to a good installation!
     
  5. Bronze_tap

    Bronze_tap Member

    That is very true - make sure the ground loop is sized sufficiently to meet the demand.
    Other usual problems with retrofit install of the heatpumps in the UK:

    1. Undersized heat emiters - ideally rads should be 4X the size of the old gas/oil system - warm the house up with 35 degrees flow, instead of 70 degrees when 0 outside.

    2. Not enough insulation (to reduce total energy loss, and the required size of the system).

    3. Not sufficient education of the end users - they try to use it as their old system, and set it on timer for 2 hours in the morning/evening (instead of using a room stat).

    4. Undersized ground loop (Not enoughf land), causing the freezing up...

    PS: Why Nobody tries to use excess heat from well sized solar thermal array (like 70-100 vacuum tubes) in the summer to recharge(thaw) the ground loop!? - you just need a couple of valves, pair of pumps and a pair of stats or controller to make it work: have a valve on the flow from the solar heater array going into a plate heat exchanger, going to the return/(pumping station).
    Than you need a valve on the flow from the ground loop circuit (with non-return valve before it goes into a heatpump unit), an extra circulator pump, and going into the heat exchanger to cullect the heat from the solar circuit, after returning to the ground loop. Also you need a separate safety cutout, to limit the temperature of the ground loop at 65 degrees, if it uses ethanol as a antifreeze, also make sure the heatpump does not come on when the ground loop circuit is hot, since it can damage it (usually they have limit of max ~30 degrees of temperature on the evaporator side of the circuit).

    So the safest bet would be use of pair of the manual lever valves, winter/summer mode, leave ONLY one of them open (+isolate the power to the HP unit when in the summer mode) or to have this functionality (use of the heat from solar colector as a means of thawing/recharging the ground loop) incorporated in the GSHP unit itself by the manufacturers.
     
  6. quality

    quality Plumber GSR

    renewable heating has developed very well since this thread started, but can be expensive initially but the long term benefits are being realised, gas has its place but it is old hat
     
  7. Sparkgap

    Sparkgap Active Member

    I think you'd find the amount of heat that a solar array could put into the ground would be totally lost and any heat would migrate away from the loops. After months of heating you might have a very slight temp rise but more likely nothing to show plus all the faff of changing over. Better using the energy to charge up a buffer tank. Personally, I would oversize the ground loops if possible to allow for any future increase and to reduce the local cooling effect. Of course, the actual sizing depends on the rate of heat transfer through the ground but having seen some systems where they had miscalculated the actual temps I'd prefer having something in reserve :)

    Undersized heat emitters: with modern well-insulated housing building fabric heat losses tend to be quite small. If you're looking at using GSHP on a radiator system with a mean temp of about 40C you'll need to have about three times the radiator compared to the equivalent at the normal 80/60C. Okay if you've got the wall space to fit them but with some modern rabbit hutches this could be an issue, hence the preference for underfloor.
     
  8. Worcester

    Worcester Plumber

    If you want to know about how to use solar thermal in the summer to reheat the ground / use it as a heat bank go here: Charging the Earth - Solar!
    Everything you needed to know is there.
     
  9. Worcester

    Worcester Plumber

    If you want to know about how to use solar thermal in the summer to reheat the ground / use it as a heat bank go here: Charging the Earth - Solar!
    Everything you needed to know is there.
     
  10. richard@earthea

    [email protected] Renewables

    We've been installing GSHP and ASHP's for nearly ten years and not had a problem...so far! Works far better on UFH/Fan assisted rads and not convection rads.
    I still get a buzz out of starting up a new install. The Gov does a grant which pays for your HP install in 5 years and you get a further 2 years bonus. Good systems- well designed and well installed are awesome and like always bad installs get all the press and are truly appalling to witness.
     
  11. Sedgy40

    Sedgy40 Member

    Until it's below 0 deg then the efficiency suffers
     
  12. Dan

    Dan Admin

    Wow that's awesome!
     
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