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Topic Title: Ground source heat pumps
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Created On: 22 January 2010 10:13 PM
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 01 December 2011 07:14 PM
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perspicacious

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 01 December 2011 07:27 PM
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OMS

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Dunno

Try this

OMS

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Failure is always an option
 01 December 2011 07:36 PM
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rocknroll

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Originally posted by: OMS

Dunno

Try this

OMS


Oh dear, Oh dear I suppose its my fault again!! LOL

regards

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"Take nothing but a picture,
leave nothing but footprints!"
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"Oh! The drama of it all."
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"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
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 01 December 2011 07:43 PM
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OMS

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Won't be the first time, bro -

OMS

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Failure is always an option
 04 February 2012 09:32 AM
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OldSparky

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Originally posted by: colinhaggett

Hi, a friend of mine has a heat pump heating his house and hot water. It seems to be using a lot of electric about £170.00 per month. It is a new build 4 bed house, do you think this about right or is it setup wrong?


sounds right to me..

they consume electric like is going out of fashion..

people seem to think they are a cheap source of heating.. wrong
 06 February 2012 09:11 AM
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HarryJMacdonald

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Is anyone aware of a kWh meter which will allow subsequent USB download to a PC? The ones I have seen appear to need permanent connection to a running PC.

I think the more expensive OWL does this. About £45.00 if I remember right.
 06 February 2012 09:53 AM
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perspicacious

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From CIBSE Journal Feb 2012 (not sure if available on line):

Various quotes:

Energy Savings Trust field trials had revealed that none of the installations had a higher CoP than 2.5. This means that none were as good as just burning gas.
The industry average CoP for GSHP is just 2.3; yet, unless it is over 2.6, it can't be classified as renewable.
'Ground-source systems must be combined with the lowest possible temperature heating system. There is not much wrong with the technology; it is how it is applied that has been the problem.'

Regards

BOD
 06 February 2012 09:59 AM
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Zs

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As this topic is back to the top I'll give you an update on the one I was involved with.

I went on a course and was instructed in how to get into the engineers' controls. It was evident that the system was using immersion for much of the time. It would not switch off. The whole unit was changed.

New patio, £16k. Free air source pump added by Ice energy to compensate for the poor performance of the original ground source. The electricity bills remained high. Eventually the client took legal action. I'm not sure where she got to with that, but she moved house.

Last month the new occupants called me to ask if I could help them with their high electricity consumption. The billed units have increased since then.

I think they would do well to change back to a conventional gas central heating system.

Zs
 06 February 2012 01:34 PM
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OMS

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I think they would do well to change back to a conventional gas central heating system.


Or buy a wood burner !!

As highlighetd in the CIBSE article, it's not the technology at fault - it's the application. To get high COP's you need source and sink at much less temperature difference - so 80C flows to normal radiators are non starter - you need nice big radiators or underfloor heating with very low flow temperatures to make a GSHP work effectively.

Regards

OMS

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Failure is always an option
 14 January 2013 10:39 AM
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varme

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Geothermal heating is an environmentally friendly and stable source of energy. Geothermal energy is thermal power produced and stored in the ground. Thermal energy is the power that establishes the warmth of matter. Geothermal energy never generates any pollution, and does not contribute to the greenhouse result.

Advantages of this type of Heating System:

1. Clean, nominal emissions of carbon dioxide

2. trustworthy and run 24/7

3. trouble-free on the earth

Edited: 14 January 2013 at 10:47 AM by varme
 14 January 2013 10:56 AM
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AJJewsbury

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Geothermal heating is an environmentally friendly and stable source of energy. Geothermal energy is thermal power produced and stored in the ground. Thermal energy is the power that establishes the warmth of matter. Geothermal energy never generates any pollution, and does not contribute to the greenhouse result.

True, but not that useful in the UK unless you fancy digging down to coal-mine depths, or happen to live in Bath.

Ground source heat pumps generally work on the principle of the heat in ground being replaced over the summer - in effect they're a solar system with a big inter-seasonal heat store.

- Andy.
 14 January 2013 03:16 PM
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leckie

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I haven't wired a ground source pump but I have done lots of air source of multiple make, including three phase.

What I have found is that on the majority of the systems, unless the manufacturers are paid to come and commission them, that the heating engineers set them up wrong. The water temperature can only be heated up to approx 40-45 degrees with most systems. Most systems will use an immersion heater or water boiler as a back up heater if the ASAP cannot achieve the temperature that the control is set to. So its a bit like setting a conventional gas boiler thermostat to say 45 degrees and using a back up electric heater to get the water up to say 50-55 degree. If you ask the system to give a setting that is too high this will cause the back up electric heater to be continually used to supplement the ashp. That costs lots of money. You only want the back heater to increase the temperature of the domestic hot water temperature, not to the radiators, for most of the time.

Also, the radiators need to be much bigger than for a standard gas boiler type system so that they can still heat the building with lower temperature water, say 40 degrees. I think that if the system sensors see a big difference between the flow and return temperatures of the heating pipes, the system drops the back heater in, lots more money again. So it needs careful design and very careful setting up and programming to get the benefit of the ashp.
 15 February 2013 10:55 PM
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Zs

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I'm bumping this thread to the top after a long rest.

I have received another enquiry about large electricity bills on an Ice Energy system. I know little about it at the moment but will keep you in the loop.

I'd like to check the current situation. Anyone got, or had anything similar going on?

Zs
 16 February 2013 10:00 AM
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bajb

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I think there is an issue with these systems not being set up properly. I have been called in to sort out two recently where the customer has put a substantial proportion of a pension lump sum into greening a house and aiming for low future running costs only to find it is not operating as expected.

Example 1. New build big house, Danfoss GSHP, UFH, solar thermal, 4kW solar pv, Chelmer ecocat, Heatmiser thermostats and programmer, woodburners, passivent. All systems installed individually quite well. The detail of the plumbing and electrical work was excellent. What was missing was someone at the top level to understand how all the systems should operate together effectively to minimise costs in all weathers that occur in each season, without the customer having to be forever tweaking controls. He was the sort of customer who wanted to pay the money and have it just work in the background efficiently. There is also a philisophical difference between the way the Scandinavians design their control systems (the Danfoss GSHP) and our British prediliction for thermostats in every room with temeratures going up and down at different times of day and night. In well insulated Scandinavian houses temeratures are designed to be more stable. I had to sort out a reasonable compromise in the programming of the various systems and correct a few faults.

Example 2. 20yr old big house, on mains gas but replaced boiler with Mitsubishi ASHP, radiators, 300 litre thermal store, wood burner with back boiler, solar thermal, 6kW solar pv. Conversly on this one, the detail of the plumbing and electrical work was sloppy. Because the ASHP is external and circulating fluid needs to have antifreeze in it, then the whole of the thermal store and internal radiator system is also full of an antifreeze mixture which is unusual. Customer had problem getting firms to turn up and do the work (deep in Wales). There were some mistakes in the set up and some errors in design and again I had to sort out a reasonable compromise in the programming to make it work. This customer is quite hands-on; the battle will be to get him to let the control systems do their work rather than forever fiddling.

I suspect there are quite a few complex domestic systems that have been put in around the country in the last few years where the individual tradesmen involved have little grasp of the overall concepts behind these systems and the systems integration is not being done properly. Because the data collection and monitoring is normally rudimentary, the customers have little idea whether it is all working efficiently or not.
 16 February 2013 09:50 PM
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Zs

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Thank you for taking the time on that bajb. Example two of yours sounds like a real pig. Is it sorted?

I agree that the set-up is critical. That last experience from some time back was clearly to do with the unit using electricity to heat the water and I am going to try to ask the new owners what is happening nowadays. In passing, they inherited me as their electrician with the property and I was putting some lights up in their garden a few weeks ago. I noticed that the patio has sprung again.

This recent enquiry comes via an email to the IET and the property is a long way away (Cornwall). Not a job I can offer to pop round to every morning with a bag of clamp meters.

In the meantime, I can't for the life of me find the details I used to have about how to get into the system engineer's side of the controls. There's an interesting section of the information screen in there which tells the engineer how many hours the unit has spent using electric back-up heating. That's the bit I am after. I suppose there are other ways of finding out about the consumption behaviour. I'm going to ask the current owners of the old one if they still have my hand-written notes in their file, which they may have. But if you have any information on which buttons to press to get into engineer's side could you let me know please? Or even a copy of the user manual might prompt me if you have one; not available on-line.

I'm still looking for my notes and if I find the recipe I'll put it on here for safe keeping.

Zs
 17 February 2013 08:59 AM
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bajb

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Still working on example 2, but last visit (probably) is this week to put in a solar pv generation monitor and configure some thermostats and a CH programmer, assuming he has put in some backboxes and insulated some pipes. It's 2 hours driving each way which is a bit of a pig and I have been spending one day there every week or two since the New Year. It gives time for things to settle down between visits. Have also put together an annual maintenance regime so I think I will be invited back once a year.

Not worked on Ice Energy so cannot help there. Do they make their own stuff or re-badge? From a quick google I see that they have installed Mitsubishi Ecodan ASHPs in the past. Mitsubishi manuals are online.

Auxiliary heating in a GSHP can potentially be a very expensive mistake if set up incorrectly. As can anti-legionella immersion heaters coming on too often. I meter both my electricity into the heating system and heat output from the system here at home for my own GSHP and anti-legionella once a week killed the overall COP. I have found anti-legionella set up on systems which are thermal stores (where the domestic hot water is only heated immediately before use). Clearly pointless in that case.
 17 February 2013 06:03 PM
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sbrown2

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I work on maintenance for a large automotive company. I used my qualifications to get on a competence and MCS scheme to push through electrics, plumbing, ventilation and heating. The properties I've certified have been:

1) New builds
2) Thus well insulated,
3) only two bedroom,
4) have underfloor heating downstairs,
5) the builder I am with wants to move this to larger properties but only by the introduction of solar,
6) there are eco solutions, but there is something as part of professional registration you see, but is ignored............................"design solution",
7) people do not want to pay for a design solution!!! or designers do not give it!!!!!!!!!!!
8) I am trying to pull out because I am aware that the benefits cannot be made without the design solution being accurate.

Any additional advice would be gratefully received.

Kind Regards

sbrown2
 17 February 2013 06:13 PM
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sbrown2

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I also missed the following:

1) we used the RHPP,
2) we are also looking to the RHI for ASHP's and GSHP's,
3) I personally have beenthinking of pulling out as the builder makes money on everything, I make money on certification only (more fool me!)
 18 February 2013 08:33 PM
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sparkiemike

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Originally posted by: Zs
I'm bumping this thread to the top after a long rest.

I have received another enquiry about large electricity bills on an Ice Energy system. I know little about it at the moment but will keep you in the loop.

I'd like to check the current situation. Anyone got, or had anything similar going on?

Zs


Do keep us updated Zs. I am currently working on a system where Ice have supplied the ASHP and under floor heating. They are due to commission in a few weeks time.

It will be interesting to see how efficient the system will be.
 18 February 2013 08:42 PM
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perspicacious

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Where a few customers have gone down the woodchip RHI route, I always advise them to have a meter fitted to record the kWh parasitic losses to run the plant. A local one has a control panel that is 65 W on standby with the District Heating (DH) pump further submetered that uses about 20% of the total.

Oddly enough, the main companies don't like my suggestion.

Yet to do ground/air source from new, but I'd advise the same, as the results on existing set ups I've done, are very revealing

Regards

BOD
IET » Wiring and the regulations » Ground source heat pumps

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