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Common problems with Ground Source Heat Pumps

Posted by on 14 October 2010 at 10:14 am

A poorly designed and installed ground source heat pump system will, effectively, be heating a property on electricity alone, which is by far the most expensive solution on a unit-by-unit basis. So what are the common problems that befall GSHPs?

1.  Slinkies. A slinky, in heat pump terms, is when the pipes that collect heat from the ground are coiled up repeatedly and wrapped over each other. This greatly increases the amount of energy being extracted per square metre, to such an extent that the ground cannot recover. More heat is absorbed than replaced, resulting in a catastrophic drop in efficiency, and forcing the heat pump to rely on its electric back up to heat the property.

2.  Cheap equipment: The delicate balance to strike with heat pumps is initial cost vs payback period. An impetus on cheaper initial cost always results in a less efficient system, that year-on-year is more expensive, and increases the payback of the system exponentially. Cheaper heat pumps have a much lower Coefficient of Performance (COP), basically the amount of kilowatts (kW) in heat produced to the amount of kWs of electricity to run the machine. A properly designed system will generate up to 5kWs of heating for every kW taken to run the machine, a cheap one can be as low as 1:1.3!

3.  Lack of installer knowledge: In the rush to jump on the “green pound” bandwagon, a plethora of firms are embarking on heat pump installations without any prior experience in the field. They are not just like traditional plumbing systems and the effectiveness of the system hinges on everything being designed and installed correctly. There have been examples of companies insulating the very pipes supposed to be drawing heat from the ground, and then docking them into the wrong part of the heating system!

Picture by Patrick Hoesly

More information about ground source heat pumps from YouGen

Heat pumps information page

Does your ground source heat pump cost too much to run?

Ground source heat pumps don't need immersion heaters

Heat pumps: 12 tips for people thinking of installing one

 

If you have a question about anything in the above blog, please ask it in the comments section below.

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Comments

7 comments - read them below or add one

Rosemary

RosemaryComment left on: 24 January 2017 at 2:46 pm

We are part-owners of a small mid terraced house, (housing association) that was built 6 years ago. We have ground source heating which works well apart from the noise of the pump - Greenline HT Plus. The pump has been sited on the first floor in the airing cupboard which is situated between the two bedrooms. I would like to know if you can suggest how we can reduce the noise especially at night. The housing association insist that they have followed the correct proceedures as it is on a flat base. I would be very interested in your opinion

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malcolmcro

malcolmcroComment left on: 20 February 2011 at 8:49 pm

I have gone a little further in my quest for the best performing heat pumps and would like to ask the experts a question.

I have found a German user web site showing many users to be getting COP of over 5. It is http://www.waermepumpen-verbrauchsdatenbank.de/index.php?lang=en and makes interesting reading. I followed up one of the oldest and best manufacturers, WATERKOTTE who talk about the best installations having a borehole delivering input at 12 degrees C, which they say gives optimum efficiency. Boreholes I have seen here deliver -4 degrees currently in February.

Is this the main reason for our lower efficiencies?

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Cathy Debenham

Cathy DebenhamComment left on: 6 January 2011 at 5:15 pm

Hi Anlyon

Sorry to hear you're having difficulty with your heat pump. Is it a ground source or air source? If you let me know I'll point one of the experts at your question and see what they have to say.

Cathy

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anlyon

anlyonComment left on: 4 January 2011 at 11:54 am

I'm someone who is experiencing real frustration at getting issues with my heat pump resolved. It seems very difficult to get a engineer to actually come out and look at the problem and telephone based diagnostics seem hopeless. They seem to lob every problem back to the developer... and then guess what they do...

My experience of my ground source heat pump is that when it goes wrong (and over two years this has happened more frequently than I had hoped for) I get hammered with costs. Any tips? Can I change the company that service my heat pump?

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Stirling Consulting Limited

Stirling Consulting LimitedComment left on: 24 October 2010 at 10:53 am

In light of the Energy Saving Trust Report and our experience can any reader interested complete the following enquiry via our blog on:

http://groundsourceairtowaterheatpumps.blogspot.com/2010/10/practical-observations-requested.html

Thanks,

Joanna

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malcolmcro

malcolmcroComment left on: 21 October 2010 at 5:19 pm

As a recent purchaser of a GSHP I find your article of little help to the prospective purchaser.

If you quoted the often claimed safe figure for drawing heat from the ground of 40w per square metre then any buyer could tell whether there would be problems ahead.

Similarly price is not a good guide to performance. There are plenty of installers who know how to charge high prices but cannot do the job. There are plenty of buyers who have no better advice than that given by the salesman.

We must develop reference sites in which the user can prove the efficiency of his heat pump to a prospective buyer. Only then can we change the abysmal image of the UK GSHP installations compared with the German in the latest EST report.

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Kensa Engineering Ltd

Kensa Engineering LtdComment left on: 15 October 2010 at 11:51 am

Duncan, (I presume this was written by you), I have to disagree with a number of points and think your article requires clarification . 

Slinkies - This has been the preferred choice for Ground Source arrays by Kensa since 1999, when the company was formed. We have thousands of installations which use these successfully without any problems. Initial research on ground array design was carried out by Oklahoma University in the US and found that slinky ground arrays provided a number of benefits, such as reduced digging. Your point should be that any ground array needs to be sized correctly and installed correctly, this is true of straight pipe, slinkies and boreholes! If they are not designed properly or installed then this is where the problems occur.

Many systems in the market place use an in built electric immersion heater as their get out of jail card, so deliberatly undersize their ground arrays and rely on the immersion heater to compensate for this. Obvisously this results in higher running costs and carbon emissions. I feel this is done without the clients knowledge and is one thing that should be heavily penalised or banned in the industry.

Cheap Equipment - This is the same in any technology, you get what you pay for! Whilst true, its slightly different for heat pumps, as to get access to any grants, such as the RHI, you need to use MCS approved equipment which states minmum performance figures for units. Of course if you then go and install it incorrectly or in the wrong application, like a drafty uninsulated church, then this is where the performance will suffer. Any installer or company selling heat pumps should know this as this is why application is so important. Heat pumps do not suit every application!

Lack of installer knowledge - again the same for any technology and where there is growth you will also find opportunists. MCS is trying to rectify this, however as a scheme it does need to grow more teeth. It would be interesting to know how many companies have been removed due to poor installation and customers compliants?

I think the majority of the points in the blog are relevant to any technology, ground source, air source, solar, or even other non-renewable technologies.

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