Ground source heat

Discussion in 'Renewable Energy' started by Wendy10, Jul 3, 2015.

  1. storming

    storming Member

    Black Isle
    Ok bin reading this with interest as I have a new build coming up. Anyone lay the pipes along side the waste pipes and then alongside the soak away pipes and gravel to recover the heat out of the bath water etc ?

  2. akaPABLO01

    akaPABLO01 Member

    Waste water heat recovery.

    Ideal for your situation.
  3. storming

    storming Member

    Black Isle
    Well I was thinking we have probably 100 m through the yard to go before we reach the field where the sewage plant will be an the following soak a way. The total length of this is likely to be half the distance of the ground source loop which can only be a good thing ........can’t it ? :scratchhead:

  4. akaPABLO01

    akaPABLO01 Member

    How much pipe is going in the ground after the 100m yard run?
  5. storming

    storming Member

    Black Isle
    That takes us to the start of the field. There is likely to be approx 100m soak a way ( next to waste heat ) then another two to three hundred metres dependant on what’s required but being on a farm , area of field is not an issue.

  6. akaPABLO01

    akaPABLO01 Member

    current planning ground array for 5 bed detached new build, check out the solar thermal collector LOL, plenty of digging

    13kW Kensa
    9x 50m slinkies

    Attached Files:

  7. bosses son

    bosses son Member

    How much would a ground source system cost? And are there any grants etc available?
  8. akaPABLO01

    akaPABLO01 Member

  9. bosses son

    bosses son Member

  10. akaPABLO01

    akaPABLO01 Member

    There are multiple applications for receiving rhi whether it’s a domestic rhi or a commercial rhi, these are the two main bands.

    Domestic rhi is paid over a period of 7 years and is usually a higher rate then the commercial rhi.

    RHI - renewable heat incentive.

    Payments made for producing heat from electricity, biomass, air and solar.

    Let’s take the two main ones being air and electricity. Biomass uptake has reduced its standing in the payment table due to mass size in rollout being systems in the range of 500kWth upwards. You don’t usually see electricity and air rolled out in this scale so the rhi payments have actually increased every April until there is enough interest and government quotas are reached. The rhi as a whole will be getting a audit averhall April 2020 I think, the review is to understand whether subsidies are to be cut or continued. As said, this will rely on the rollout being cost and efficiency.

    The two main uptakes are air and electricity. Ground source heat pumps combine with ground thermal heat and can handle larger less insulated properties. The Achilles with air is that larger properties require maybe two units in what’s called a cascade system. This makes equipment and installation considerably costly.

    I’ve just completed an analysis for a 5 bed converted school in penines needing 2 x 14kW Mitsubishi with 28mm carcass, 600mm solid sandstone wall, pre 1900. The maximum rhi for air source is just a smidge over £10,000. Cost of install, 26 rads, kickspace kitchen heater, full heating and hot water carcass... upwards of £30,000.

    If they had land and ground then their potential rhi would be £30,000.

    Their current heat, LPG, about 8p /kWth

    The heat pumps can be a ratio of 3.65/electricity unit cost let’s say £0.16, this then becomes £0.0476p /kWth, nearly halving heating costs.

    That covers 1 site using different heat pumps.

    Then there is commercial instal and there are two different types but both only use gshp as the technology. These types are shared ground and shared heat pump or shared ground, heat pump in each building. The later refers to types of property such as neighbours sharing a ground or flats (apartments) each with their own heat pump. These are paid on their epc value over 20 years. If they use more heat then the epc as registered on the heat meter then they do not receive more then the epc will allow.
    The second (which is the best) is if you have a farmhouse, converted barn, stables, new build. You use one ground array, multiple heat pumps in cascade with once buffer for heating and large cylinder to cover 3 property or more water needs. This then is paid by size of heat pump, the usual is about 45kW.
    45x 1314= 59,130kWth qualify for tier 1 payment, the extra units are paid at tier 2 level

    Tier 1 £0.0961
    Tier 2 £0.0279

    Let’s say all three use 80,000 kWth

    59,130x0.0961= £5,682.39

    20,870x0.0279 = £582.27
    = £6,264.66

    X 20 years = £125,293

    Typical install cost £56,000, ground and civics by farmer.

    Cost to run about £3,809 /annum.

    Commercial air is about 2p in tariff and doesn’t really pay.

    Non domestic rhi

    20 years

    Domestic rhi

    7 years
  11. Farmer_Joe

    Farmer_Joe Member

    the idea is below 1 m the ground is a constant temp, the wetter the better i tried to lay mine almost diectly into wet clay with bits of sand where it was stoney so it conducts to the ground really well.

    if your soakaway is gravel the heat will not conduct out of the gshp pipe into the ground well at all, i suppose you could run it in the same trench as the soil pipes but i would run them at either side of the trench personally.
    storming likes this.
  12. bosses son

    bosses son Member

    Thanks for explanation. You say costs to run, is this mostly electricty costs. And will it heat my house well?
  13. akaPABLO01

    akaPABLO01 Member

    Yes and yes. Even though most renewable energy applications are pigeon holed under the same umbrella the only true renewables are solar PV and solar thermal. Everything else is a step child. Air and ground are electricity run from power stations that still use fossil fuel but their effectiveness in efficiency using that 1kW of electricity makes them the best heat producers on the market using less “fuel”.

    You need a full heat loss survey doing. This will identify needs and equipment. Quite possibly bigger radiators to help emit the heat due to lower circulation temperature @ 50°.

    I would look at both options of air and ground as one will be better then the other for your need.

    You’ll also need loft insulation up to a minimum of 270mm.

    The above scenarios were designed specifically for those sites using most cost effective solutions with efficiency in providing heat demand. Every site is different.
    Peter likes this.
  14. bosses son

    bosses son Member

    It would work well for someone with a turbine or solar panels then.
  15. akaPABLO01

    akaPABLO01 Member

    Definitely helps.

Share This Page