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  • FIRST POST
    • lovesgshp
    • By lovesgshp 6th Jan 11, 7:18 PM
    • 1,258Posts
    • 707Thanks
    lovesgshp
    Ground Source Heat Pumps
    • #1
    • 6th Jan 11, 7:18 PM
    Ground Source Heat Pumps 6th Jan 11 at 7:18 PM
    If anyone wants info on these, then please let me know, as have had one for over 5 years.
Page 2
    • lovesgshp
    • By lovesgshp 9th Jan 11, 10:45 PM
    • 1,258 Posts
    • 707 Thanks
    lovesgshp
    Welda
    I will answer everything that I can on the subject without any spin or sales talk. I have only association with a well established Italian Geothermal company (10 years old ) and none with any in the UK.
    • lovesgshp
    • By lovesgshp 9th Jan 11, 10:51 PM
    • 1,258 Posts
    • 707 Thanks
    lovesgshp
    Spot on Chippy, system basically sucks out more heat energy that can be replaced by normal solar activity. Bore hole and surrounding area is froze!!

    Originally posted by welda
    Wrong!!! Temps at 1.5 mtrs are fairly constant. Refrigerant in the exchanger boils at 0C. I watched the domestic hot water heating thismorning from 46C to 52C in less than 10 minutes.
    • thechippy
    • By thechippy 9th Jan 11, 11:11 PM
    • 1,919 Posts
    • 2,480 Thanks
    thechippy
    Wrong!!! Temps at 1.5 mtrs are fairly constant. Refrigerant in the exchanger boils at 0C. I watched the domestic hot water heating thismorning from 46C to 52C in less than 10 minutes.
    Originally posted by Geotherm
    Nope,

    You are wrong. The environment cannot replace the heat at the same rate as it's extracted. Note that I said it can be several years before it's noticed.

    There is an actual example somewhere of a village that's been run off a gshp for several years and the efficiency is now dropping off substantially.
    Happiness, is a Kebab called Doner.....
    • lovesgshp
    • By lovesgshp 21st Jan 11, 11:09 AM
    • 1,258 Posts
    • 707 Thanks
    lovesgshp
    Nope,

    You are wrong. The environment cannot replace the heat at the same rate as it's extracted. Note that I said it can be several years before it's noticed.

    There is an actual example somewhere of a village that's been run off a gshp for several years and the efficiency is now dropping off substantially.
    Originally posted by thechippy
    Thanks Chippy. Sorry for the long delay in answering, but the thread has only just been reinstated. Do you have any info or articles about this village, as would be interesting reading.
    I monitor my pump here and have not seen any performance reduction over the last 5 years. If you take the basis that in winter, a heat pump is running circa 10 hours per day, with a flow rate on a ground loop of 11 ltrs per minute (for a 11Kw output unit) , then the recharge time is longer for the loop. At the moment, I am getting 6.0C in with 2.0c out Outside temp 2.0C and snowing today). As the heating need is reduced in say Spring, this then starts to rise and during the summer we get even higher inlet temperatures. Some people use the ground loops to slightly cool the house, as passive cooling in the Summer months, when outside temperatures are higher than the feed in temperature
    Last edited by lovesgshp; 21-01-2011 at 11:11 AM. Reason: forgot outside temp
    • markums
    • By markums 21st Jan 11, 11:14 AM
    • 22 Posts
    • 38 Thanks
    markums
    (reply to post 23)

    So the advice would then be to add 50% or 100% to the recommended size of the ground loop?
    I've always wondered about how different the 'cooling factor' of a pump would really be in wet ground and dry ground. I would imagine the wetter ground being better for pumps due to how easily the heat is transferred and the moving water table being refreshed constantly and gradually over months/years.
    Or am I just being a bit thick...
    Last edited by markums; 21-01-2011 at 11:25 AM. Reason: To avoid confusion over who I was replying to.
    • lovesgshp
    • By lovesgshp 21st Jan 11, 11:32 AM
    • 1,258 Posts
    • 707 Thanks
    lovesgshp
    (reply to post 23)

    So the advice would then be to add 50% or 100% to the recommended size of the ground loop?
    I've always wondered about how different the 'cooling factor' of a pump would really be in wet ground and dry ground. I would imagine the wetter ground being better for pumps due to how easily the heat is transferred and the moving water table being refreshed constantly and gradually over months/years.
    Or am I just being a bit thick...
    Originally posted by markums
    To increase the length of the ground loop would only incur far much extra cost. You only get about .25C per extra 10 mtrs. A recent installation had 2x11kw pumps, with 2 x 162 mtr excavations so nearly 650mtrs of available heat input, 3 mtrs apart carrying 2 input/outputs in each. House size 360 sq mtrs using radiators.
    Yes, wet soil is far better at holding heat than sand, and any installation company should take those facts into account when designing a system.
    • Cardew
    • By Cardew 21st Jan 11, 12:40 PM
    • 26,902 Posts
    • 13,048 Thanks
    Cardew
    House size 360 sq mtrs using radiators.
    Originally posted by Geotherm
    360 sq metres - all heated? That is a BIG property.
    • markums
    • By markums 21st Jan 11, 1:03 PM
    • 22 Posts
    • 38 Thanks
    markums
    Have you come across many people doing their own digging and backfilling of trenches? Does it need to be done by people who have full licenses to comply with installation standards or anything?
    I ask as i've done alot of digging and plant work myself before and thought when i get around to it, this could be a massive saving for me.
    • lovesgshp
    • By lovesgshp 21st Jan 11, 1:04 PM
    • 1,258 Posts
    • 707 Thanks
    lovesgshp
    360 sq metres - all heated? That is a BIG property.
    Originally posted by Cardew
    Hi Cardew.
    Many of the properties here are old farmhouses that have been restored. The one above is in Tuscany. The norms are around 200+ sq mtrs. Local to myself there are 2 houses 240 sq mtrs using 14Kw pumps, 260 and 300 sq mtr using 17Kw output units
    • lovesgshp
    • By lovesgshp 21st Jan 11, 1:15 PM
    • 1,258 Posts
    • 707 Thanks
    lovesgshp
    Have you come across many people doing their own digging and backfilling of trenches? Does it need to be done by people who have full licenses to comply with installation standards or anything?
    I ask as i've done alot of digging and plant work myself before and thought when i get around to it, this could be a massive saving for me.
    Originally posted by markums
    The way that we install here is as follows: Once we get all the technical detail of the property and size the pump, then we mark out the excavation lines. The normal depth is 1.2-1.5 mtrs. If 2 excavations they should be mimimum 3 mtrs apart and 1.2 mtrs wide. A local excavation company will normally do this and then an engineer will arrive for supervising the loop layout and pressure testing before the backfill. Depending on the soil type, sand may be required under and over the loops.
    The ground loop collectors ( which must be accessible ) should be at a maximum distance from the house of 40 mtrs and at a depth of 60 cms with the lines insulated and from them to the house/heat pump.
    There is no reason why you could not complete the excavations yourself.
    Last edited by lovesgshp; 22-01-2011 at 5:13 PM. Reason: clarify collector depth etc
    • welda
    • By welda 21st Jan 11, 1:58 PM
    • 580 Posts
    • 270 Thanks
    welda
    Why was the thread pulled, then re-instated?
    • lovesgshp
    • By lovesgshp 21st Jan 11, 2:27 PM
    • 1,258 Posts
    • 707 Thanks
    lovesgshp
    Why was the thread pulled, then re-instated?
    Originally posted by welda
    You can see my question on the site feedback forum under the spam buttons heading and MSEAndrea kindly reinstated this discussion
    • welda
    • By welda 21st Jan 11, 4:30 PM
    • 580 Posts
    • 270 Thanks
    welda
    You can see my question on the site feedback forum under the spam buttons heading and MSEAndrea kindly reinstated this discussion
    Originally posted by Geotherm
    I was bewildered as to why post was pulled, specially as questions were beginning to open up a reasonable debate regarding GSHP, an area that has interested me for a long time!

    • thechippy
    • By thechippy 23rd Jan 11, 8:32 PM
    • 1,919 Posts
    • 2,480 Thanks
    thechippy
    Thanks Chippy. Sorry for the long delay in answering, but the thread has only just been reinstated. Do you have any info or articles about this village, as would be interesting reading.
    I monitor my pump here and have not seen any performance reduction over the last 5 years. If you take the basis that in winter, a heat pump is running circa 10 hours per day, with a flow rate on a ground loop of 11 ltrs per minute (for a 11Kw output unit) , then the recharge time is longer for the loop. At the moment, I am getting 6.0C in with 2.0c out Outside temp 2.0C and snowing today). As the heating need is reduced in say Spring, this then starts to rise and during the summer we get even higher inlet temperatures. Some people use the ground loops to slightly cool the house, as passive cooling in the Summer months, when outside temperatures are higher than the feed in temperature
    Originally posted by Geotherm
    Sorry Geo,

    Can't remember where I read it. It was mentioned by another engineer months ago and I managed to find it on google. Just had a google and can't find the article as we speak.
    Happiness, is a Kebab called Doner.....
    • lovesgshp
    • By lovesgshp 24th Jan 11, 12:35 PM
    • 1,258 Posts
    • 707 Thanks
    lovesgshp
    Sorry Geo,

    Can't remember where I read it. It was mentioned by another engineer months ago and I managed to find it on google. Just had a google and can't find the article as we speak.
    Originally posted by thechippy
    No problem Chippy. Further to your post, I tried an experiment here, where the pump was only used for DHW, so circa 1 hr per day. I used a woodburning inset fire so we did not freeze, but that does not have any relation to the heat pump, so completely independant heating.
    The ground loops recharged temperature at a higher level, than 5 years ago in the same period, through less input, but you have to remember that they pull out more heat in the winter, on a longer operating time.
    I did ask our engineers, who solely deal in heat pumps, but I could not repeat the reply!!! The engineer that told you was a geothermal guy I presume ?
  • kje
    David Nicholson-Cole from Nottingham has a very good blog about his home which has PV, solar collectors and GSHP (two boreholes). It does have a lot of data on it as it seems to have been run as a university project as well as his own home eco project, so is more "scientific" than some of the claims bandied about. Google "chargingtheearth".
    • welda
    • By welda 24th Jan 11, 7:03 PM
    • 580 Posts
    • 270 Thanks
    welda
    This MSc Thesis paper may go some way to explaining loss of thermal recharge, although I reckon you will know of this possibility.

    Page 37 on pdf doc.

    http://www.esru.strath.ac.uk/Documents/MSc_2007/Le_Feuvre.pdf



    Please note copyright, link added for perusal/illustrative purposes only.
    Last edited by welda; 24-01-2011 at 7:43 PM. Reason: added info.
    • Cardew
    • By Cardew 24th Jan 11, 7:18 PM
    • 26,902 Posts
    • 13,048 Thanks
    Cardew
    This MSc Thesis paper may go some way to explaining loss of thermal recharge, although I reckon you will know of this possibility.

    Page 37 on pdf doc.

    http://www.esru.strath.ac.uk/Documents/MSc_2007/Le_Feuvre.pdf

    Originally posted by welda
    Thanks,

    I have only skimmed that section and we are not allowed to quote from the thesis(copyright) but it does seem to confirm that under some conditions what 'thechippy's' read has some validity for boreholes.
    • welda
    • By welda 24th Jan 11, 7:26 PM
    • 580 Posts
    • 270 Thanks
    welda
    Hi,

    I did notice copyright, I have edited and added info re; copyright.
    • Meatballs
    • By Meatballs 24th Jan 11, 7:46 PM
    • 410 Posts
    • 246 Thanks
    Meatballs
    You could quote it as part of a review or criticism on the work.
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