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    • CommentAuthortopher
    • CommentTimeDec 20th 2011
     
    Gusty,

    Well done mate. So glad you are so chuffed with it. Give us some news on the tweaks and consumptions.

    Congrats,........Topher.
    .
    • CommentAuthorSprocket
    • CommentTimeDec 21st 2011
     
    Congrats Gusty.
    Looking forward to hearing more about it as you live with it though the coldest bits of Winter.
    Interesting too that you've clearly decided to see how low you can go on the UFH temp.
    And that you have some radiators on the circuit - let us know how that works out.

    Our first heat pump is running (a little 4kW one has been going a couple of months now). I've taken that down very low and it's all working great but I don't know how it will do when it's really cold.
    That GSHP is in an old barn here that we have rennovated, not in the house. I'd love to do the house too but I think we would need to drive old rads for that and run a much higher temperature and so far I haven't found anywhere to put a big buffer tank :-(
    • CommentAuthortopher
    • CommentTimeFeb 6th 2012 edited
     
    Report Number 27. 6 February 2012.

    Its all obvious and predictable now, but I was surprised. When the house was first refurbished 25 years ago, it had a 9 Kw resistance heater for the under floor heat. I found that it could just maintain 19 ÂșC inside with 0 ÂșC outside. As my heat pump was 15 Kw, I calculated it could get 19 ÂșC inside with -10 ÂșC outside. I am going to find this is wrong.

    First it is not possible to get 15 Kw continuously. The pump is an on/off device and continuously raises the temperature until is is shut off by the heating curve calculation, or a temperature limit. So I am getting less than 15 Kw. I have tweaked the settings to get it to stay on as long as possible and be off for the least time. The external temperature has varied from -1 to -5 ÂșC and the inside is gradually reaching 19 ÂșC. I have recently returned to France and the internal temperature was 14 ÂșC. With the huge thermal mass of concrete and the low ambient it takes a long time to heat up.

    Second I am now not sure if the underfloor system is able to transfer enough heat into the building when it is very cold outside. The water temperature in the underfloor pipes varies from 32 to 42 ÂșC. If I could keep it at a constant 42 ÂșC, I would get a better heat transfer.

    EDF the electricity supplier are having a bonanza period. With the cold weather they are making every day allowable a 'red day' with the very high tariff. Grrrr.

    Update on 8 February. I was right about EDF, all week days are red, Saturday is white, only Sunday is blue which is must be.

    Last night it went down to - 7 ÂșC. The inside temperature dropped from 19 to 18 ÂșC, so it looks as if my heating capacity is able to cope with around -4 to -5 ÂșC outside. If I could turn the clock back and redesign it, I would have a heat pump with proportional control, if such a product exists. I am not sure if a bigger buffer cylinder would help, it would take longer to give out the heat before the pump started again, but I think the net result would be the same.
    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 6th 2012
     
    How are you notified that it is a 'Red Day'?
    • CommentAuthortopher
    • CommentTimeFeb 6th 2012
     
    Hi SteamyTea,

    There are three ways.

    1. You can ask EDF to send you an email, this arrives around 4 pm in the afternoon and tells you what tariff it will be tomorrow.

    2. I have a little box plugged into the mains. It tells you what the tariff is today, and at around 8 pm it tells you what it is going to be tomorrow.

    3. From experience and the weather forecast you can make a guess. For example this week is forecast to be very cold, and EDF have lots of red days left to use. So I predict (with almost 100% certainty) all this week will be red days. When the ambient is milder and most of the red days have been used up it is less predictable, a cold day tomorrow could be red, or white. Sometimes at the end of the heating season, if they have some red and white days left they use them up indiscriminately because they have to.

    I use all three methods.

    You may be interested to look at

    http://bleuciel.edf.com/abonnement-et-contrat/les-prix/les-prix-de-l-electricite/option-tempo/l-historique-52426.html

    It shows the current year to date.
  1.  
    Posted By: SprocketI'd love to do the house too but I think we would need to drive old rads for that and run a much higher temperature


    I recently installed a Daikin Altherma HT ASHP which is actually two heat pump circuits in series. The first circuit draws heat from the air and delivers the working fluid into the house at about 20-30degC (I think). The 2nd circuit takes heat form this fluid and boosts it, to transfer it into the CH water at 75degC. This runs the existing radiator circuits (old farmhouse with no UFH). No backup heater or thermal store. Air temp has been -7degC here last week and all works fine.
    By comparing this years elec meter readings against previous years oil consumption, I believe the overall system CoP has worked out at about 2.5-2.7.
    Downsides: 1) the second circuit is all inside the house so bit noisy (should have put it in a garage) 2) its more complex than a 'normal' HP so purchase cost was bit more expensive. Reliability unknown but no issues yet.

    I chose it as a drop-in replacement for an oil boiler without needing to replace the whole house heating (actually it turned out to be a lot more work than jut dropping it in).
    Am surprised there are not more HPs that work like this, as overcome the well known problems losing temperature and CoP during winter just when you need the heat the most.
    • CommentAuthortopher
    • CommentTimeFeb 6th 2012 edited
     
    Report Number 28. 6 February 2012.

    In the early part of this story, there were questions about the bore holes. Would they provide enough heat to the heat pump. Well, for that bit at least I think it is OK, just as Paul in Montreal had said it would be. I have 2 x 100 meter boreholes with two loops in each borehole, this feeds a 15 Kw heat pump.

    Following continual use over one week, at worst the supply is +7.1 ÂșC and the return +2.6 ÂșC. I believe Nibe's specification for COP measurement requires a primary supply of 0 ÂșC and an output of 35ÂșC.

    8 February update. The heat pump has now been going flat out for 8 days and the worst temperatures are now +5.9 ÂșC supply and + 1.8 ÂșC return.
    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 6th 2012
     
    Thanks
    • CommentAuthortopher
    • CommentTimeFeb 15th 2014 edited
     
    Report Number 29. 15 February 2014.

    The heat pump had been working without problems until 5 Jan 2014. I was in the UK and a friend who checked the house regularly told me that it had stopped with a temperature alarm. I contacted the installer, and after a few days he was able to investigate. He found the return temperature from the primary circulator to be minus 8 degrees; In my experience, it had never been lower than plus 2 degrees - clearly a wrong value. This circuit pumps the glycol around the closed loop that takes the heat from the two 100 meter deep boreholes. This value caused the system to shut down. He thought (wrongly) that the sensor was defective and ordered a new one. After 11 days it finally arrived.

    The result was the same. He found the circulating pump for the primary had stopped working, hence the minus 8 degrees. The pump is a specially made product by Grundfos for Nibe the heat pump manufacturer. A new one off the shelf, can only be purchased from Atlantic, the agent for Nibe in France. Its retail cost is 1,572 €. The pump caused a 4.5 amp fuse to blow and gave off that tell-tale smell of burning electronics.

    When the system was installed I paid 466 € to have it set up by an 'expert'. I was not impressed by his 'expertise' but I was also buying 3 years insurance, so fortunately, I will not have to pay the huge cost of the new pump.

    Finally on 13 February (39 days after the fault was first reported) the new pump arrived. It was smaller than the old one and is marked efficiency 'A' like a fridge. Apparently there have been three different designs of this pump over the years. This must be in my view, because of reliability issues. The pump has a permanent magnet and I assume it is a DC device. The control electronics is in a plastic container mounted on the side of the pump. Its speed can be varied remotely. I have set it to 85% of full speed, this gives a supply/return temperature difference of 5 to 6 degrees.

    I expect to be presented with a bill for manpower. If/when it arrives, I will ask for a contribution from Atlantic on the grounds of the product having an inherent design defect. As I am in France, I will probably lose.

    Let me know if anyone is reading this and wants to hear the end of the story. OK thanks for your interest. Things happen slowly here, when something happens, I will let you know.
    • CommentAuthorTriassic
    • CommentTimeFeb 15th 2014
     
    Yep someone here and eager to hear what happens next....
    •  
      CommentAuthordjh
    • CommentTimeFeb 17th 2014
     
    Lots of us, I expect, not just Triassic on his lonesome ...
  2.  
    As a seasoned GSHP owner, I'd also like to hear ...
    • CommentAuthortopher
    • CommentTimeFeb 18th 2014
     
    Thanks to all for your continued interest - very gratifying.

    While I am waiting for a probable bill for manpower, I tried to find out about the primary circulator. I was trying to find if it had a design defect. The original one was a Grundfos Magna model GEO 25-100 180. Part number 969 17 292. The new one is noticeably smaller and has the electronics mounted in a different way. It is model UPM GEO 25-85 180, part number 976 38 525. I telephoned Grundfos UK, they had no information, saying that it would have been supplied to Nibe from a European OEM part of the company. I have sent an email to Nibe HQ in Sweden to see what that produces.

    Now for something completely different - my compressor has had 6,090 starts in 3 heating seasons, its running time is 1,853 hours (average run time 18.25 minutes). Anyone know a typical lifetime for a compressor? Paul (in Montreal) your system must have been going for a few years now, do you know how many starts yours has made, and the total running hours?
  3.  
    Posted By: topherAnyone know a typical lifetime for a compressor? Paul (in Montreal) your system must have been going for a few years now, do you know how many starts yours has made, and the total running hours?


    No idea - there's nothing in the controller that counts. On the really cold days, the run time is over the order of 2-3 hours and then the controller interrupts it for 5 minutes. Not sure what the reason for that is. When we had the really cold weather, it was running 24/7 for a week at a time (apart from the 5 minutes off every couple of hours). We're on season 9 now, but, of course, we have the cooling season as well. I'd guess we're at 2-4000 starts per season. Once the bearings and so on are bedded in then it should run for 20-25 years I'd say assuming nothing breaks. I don't believe that it's the number of starts that determines the life unless something breaks. I guess the start wears the bearings a bit, but not that much. There's no brushes to wear out and the motor coils should last indefinitely if there's nothing attacking the insulation on them. Of course, the start capacitors will eventually give up - I've already had to replace the start/run capacitor on the blower fan, but it was an easy fix and cost me less than $10 to get 2 new ones (including shipping).

    We did have the TXV die on one of our systems though - that was a more complicated repair as the whole refrigerant loop has to be vacuumed, purged, soldered, purged and refilled.

    Paul in Montreal.
    • CommentAuthortopher
    • CommentTimeFeb 19th 2014
     
    Paul,

    Thanks........Topher

    Gusty,

    Your system has been going for two heating seasons.
    How is it?
    Are you still as happy as you were on 20 Dec 2011?.........Topher
    • CommentAuthorDantenz
    • CommentTimeFeb 20th 2014
     
    Posted By: topherReport Number 28. 6 February 2012.

    In the early part of this story, there were questions about the bore holes. Would they provide enough heat to the heat pump. Well, for that bit at least I think it is OK, just as Paul in Montreal had said it would be. I have 2 x 100 meter boreholes with two loops in each borehole, this feeds a 15 Kw heat pump.

    Following continual use over one week, at worst the supply is +7.1 ÂșC and the return +2.6 ÂșC. I believe Nibe's specification for COP measurement requires a primary supply of 0 ÂșC and an output of 35ÂșC.

    The first heating season will provide the highest source temperatures from your boreholes thereafter, they fall gradually each year over a period of about 4-5 years before stabilising.
    • CommentAuthortopher
    • CommentTimeFeb 20th 2014
     
    Dantenz,

    That's interesting. I wish I had kept a more careful record of the temperatures. If I understand correctly this means that the efficiency of the heat pump falls gradually until the temperature stabilises.

    Regards,............Topher.
    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 20th 2014
     
    unless that is taken into account at the design stage.
    • CommentAuthortopher
    • CommentTimeFeb 21st 2014
     
    Report Number 30. 21 February 2014.

    The bill arrived in the post today. 40.00 euros per hour, 7 hours work, plus 20% TVA or VAT. Total 336.00 Euros. I suppose I should be grateful, a heating technician in the UK, would probably be twice the price.

    I have decided to pay up and keep quiet. The only good thing is that the invoice includes a detailed list of the work done.

    I wanted to keep the old pump to dismantle it, but it had to go back under the terms of the insurance.
    • CommentAuthorBoggy
    • CommentTimeOct 20th 2014
     
    Topher et al,

    Many thanks for an informative and entertaining couple of hours reading!

    First may I put my pedant's hat on?
    A "meter" is a measuring device; a "metre" is the SI unit of distance.
    KWh is correct.

    I am going to install my own GSHP using long trenches, for several reasons:
    1) I already own a digger (excavator),
    2) I have enough land,
    3) Pipes (300m each) can be laid with no joins
    4) Ground is rock more than about 2m deep.
    5) Water table here is never more than 100mm from the surface (mid West Wales)

    I am going to do everything. I reckon I can save ÂŁ1000s this way and reduce the payback time, which for me is most important as I'm no spring chicken. Once we are "in credit", the actual COP matters less, and I can tweak the system in my own time to get the best performance from it.

    I will also have a solid-fuel stove for back-up.

    All the advice here has been invaluable, so thanks to you all once again.

    Boggy
  4.  
    Hi All,

    I was talking to a friend of mine over the weekend and we started on the GSHP RHI. We both went for SPF changes from the default 2.5 the RHI try to give you. Mine came back as 4.1 and theirs 3.1. The units are different and they trenched. I had to bore as I did not have the land. Would this have made such a difference to the SPF of our HP's? It will make a significant difference to RHI payments that is for sure.

    Thanks in advance.

    Also west Wales.:tooth:
    • CommentAuthordb8000
    • CommentTimeOct 22nd 2014
     
    Just found this because of the updates.
    Topher, since you wanted feed-back; thank-you it was an extremely interesting and helpful thread.
    Dave.
    • CommentAuthorSprocket
    • CommentTimeOct 22nd 2014 edited
     
    Hi Gusty

    Two GSHPs here get 4.1 and 4.3 after uplift. Both are on boreholes.

    I don't know if/how boreholes vs trenches are considered for SPF though. They might be.
    I think I would expect floor type (assuming UFH) and secondary flow temperature to be biggest factors considered though.
    I think GSHP sizing and presence of any supplementary heat source are a big deal for the green deal assessment (though not affecting SPF).
    • CommentAuthortopher
    • CommentTimeJan 14th 2015
     
    Report Number 31. 14 January 2015

    In total I believe I have had 4 leaks from brass fittings. This could have been due to defective fittings or plumber over tightening. I suspect the latter. With the constantly fluctuating temperatures, any weakness will be assisted to fail.

    The most recent a year ago was in the primary. The antifreeze mix leaked out, and the heat pump shut down due to poor circulation. The liquid escape was not excessive but it made the chipboard flooring become like soggy cardboard. Finally this spring time I am going to disconnect the heat pump, move it, fix the soggy floor, and re-install it; rather a plumber and a carpenter are going to do the work.

    Apart from this, it continues to work well. I find I have to adjust the settings when the ambient is mild and adjust again when it gets cold. I do this to achieve at least 18 minutes of 'on' time for the compressor. I have not found compromise settings that would give 18 minutes minimum in both mild and cold conditions. If anyone has suggestions on this I would be pleased to hear them. Nibe heat pumps have a huge variety of settings - probably too many. For example the heating curve slope can be varied, max and min can be set, overshoot set, a kink can be put in the slope, and more. . . .
    • CommentAuthortopher
    • CommentTimeJan 15th 2015
     
    Boggy,

    A request - would you give us a regular update on how your project develops please? When you encounter problems the people who read this may help with solutions. I got help with my setbacks. Your readers will be interested to know how it is going too.

    My apologies for getting meter and metre mixed.

    I dont understand this bit "the actual COP matters less, and I can tweak the system in my own time to get the best performance from it."

    My understanding is that the COP of a heat pump is a measure of its performance with defined things like input water temperature. So if your heat pump has a COP of 3.0, you put in 1 Kw and get the equivalent of 3 Kw of heat out. If you have a COP of 4.0, you put 1 Kw in and get equivalent of 4 Kw out, that is 25% better. Tweaking will make your system work better and you will be able to get closer to your theoretical COP.

    Or have I got the whole thing wrong?

    Regards,..........Topher
    •  
      CommentAuthorSteamyTea
    • CommentTimeJan 15th 2015
     
    CoP, or coefficient of performance is slightly more complicated as it is comparing one sort of energy with another, usually electrical with thermal. If you looked at just the thermal energy that went in i.e. from the ground loop and compared it to the energy that came out, then your CoP would be less than 1.
    Best to think about it as a multiplier, or a big leaver.
    If you want to get really technical then start looking at thee Gas Laws and phase changing, or think of it as I do as a simple PV/T calculation.
    All this is saying is that if you change one Pressure, Volume or Temperature, the other can change. So if you have a box of gas, squeeze it until it is half the volume, the temperature goes up, but the energy content is the same.
    • CommentAuthortopher
    • CommentTimeJan 15th 2015
     
    SteamyTea,

    I don't agree. . . . .

    I got this quote from Wikipedia http://en.wikipedia.org/wiki/Coefficient_of_performance

    A geothermal heat pump operating at COP_{heating} 3.5 provides 3.5 units of heat for each unit of energy consumed (i.e. 1 kWh consumed would provide 3.5 kWh of output heat). The output heat comes from both the heat source and 1 kWh of input energy, so the heat-source is cooled by 2.5 kWh, not 3.5 kWh.

    It is perfectly fine to measure heat output in kWh.

    My point to Boggy was that the COP of the heat pump is fixed by the design. It is possible to tweak the COP to the highest value by raising the primary input water temperature (if possible) and lowering the secondary water temperature. This is why underfloor heating with its lower water temperature is better than radiators for heat pumps.

    If Boggy gets a GSHP with a lower COP it will cost more to run than one with a higher COP, assuming he tweaks each to max efficiency.

    See http://www.nibe.co.uk/Home-Owner/NIBE-Heat-Pumps/Ground-source-heat-pumps/Product-range/NIBE-F1245-ground-source-heat-pump/ It says that . . . . .
    Nibe model F1245 8 Kw, as two COP values in the specification.
    With 0 degrees input and 35 degrees output COP = 4.44
    With 0 degrees input and 45 degrees output COP = 3.55

    So 0.89 kWh less output with the higher secondary temperature.
    • CommentAuthorMikel
    • CommentTimeJan 15th 2015
     
    It is probably more sensible to restrict the term CoP for a heat pump to the tested performance figure, e.g. as per EN14511 and use the SPF as that is what is going to be achieved in practice.

    Tested CoPs will vary according to type of heat pump (GSHP, A2W, A2A) and defined inlet and outlet temperatures.

    I have an electricity meter and heat meter fitted to our GSHP (producing heating and DHW to 50C) and currently weekly SPFs are approximately 3.5. The EST reports have differing definitions for SPF, which can further complicate matters! The CoP for the GSHP from the manufacturer's spec sheet is 4.16.

    WRT to the RHI, the SPF of the heat pump is calculated according to

    https://www.ofgem.gov.uk/publications-and-updates/heat-pump-spf-calculation-template
    Our system came out as SPF 3.1 from a re-assessment for the RHI using this method

    the heat pump is sized according to MCS 3005, specifically BS EN 12831

    and what you get back from the RHI will come from the deemed heating and DHW figures from the EPC or SAP for a new build.
    • CommentAuthorskyewright
    • CommentTimeJan 15th 2015 edited
     
    Posted By: MikelWRT to the RHI, the SPF of the heat pump is calculated according to

    https://www.ofgem.gov.uk/publications-and-updates/heat-pump-spf-calculation-template

    Nice. Thank you.

    I wonder if anyone in the government/Civil Service has heard of ods format?
    •  
      CommentAuthordjh
    • CommentTimeJan 15th 2015
     
    Posted By: skyewrightI wonder if anyone in the government/Civil Service has heard of ods format?

    Yes, DECC have. I had a long exchange with them a few years ago when they refused to accept a submission from me just after the government's open standards initiative started. They have a long-term maintenance contract with a multinational that means it's uneconomic for them to update their systems beyond whatever it was (Windows 98? I don't remember). Typical PFI-like government contractual naivity.
   
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