Ground Source Heat Pump Questions

miceri

I was at an exhibition in Aberdeen at the weekend, and spoke to various people about heat pumps, solar PV etc. and one of the guys I spoke to thought I might need 2 bore holes to accomodate a property of my size, I presume he's exaggerating then?

I have had a look at Air source heat pumps as well (same manufacturers as the ground source pumps), but they seem to be very different from the Mitsubishi ones you highlighted.

Yes, the Heat pumps I've looked at, have either had water tanks built in, or the option of hooking them up to an external tank.

Nibe was one of the manufacturers I've been looking at. Overall I think their kit has impressed me the most.

Thanks for that, good pictures.
I've no problems regarding information after the exhibition at the weekend. I've obtained literature from Nibe, Danfoss and Worcester Bosch. I've just got to read through it all now

Yeah, i'll have to get a few companies round to give me estimates at some point. No way near that stage yet though, just gathering information.

Thanks very much for your help.
Much appreciated
Hamish

ham1sh

255sqm

I read sqft

In sqm, my house is 290sqm heated and another 37sqm for the non-heated attached garage.

We only have 1 bore hole, I know of people who have drilled 2 for similar and smaller properties. 2 bore holes are required to 'cycle' less, but you also must factor in the costs of drill an additional hole. I also think that not all of the pump units are equipped for that... They also must be a certain distance apart, or you will be drawing geothermic heat from the same place.

So he wasn't pulling a fast one!

It also depends what else you will do with the house in terms of additional / complementary heating & ventilation systems. As I said previously, I am planning floor heating (waiting for the daft builders to send estimates in), heat efficient ventilation, triple glazing etc.

So, 1 bore hole was plenty enough for me.

As I now understand you have 255sqM, then forget the heat exchanger method, you do need something more substantial.

What type of terrain / location is your house?
You can also get heat pumps very similar to this that can be installed in a lake / sea if you have water very close, you can also have your entire garden dug up, and masses of piping laid to act as a collector in the ground. This is pretty useful for new builds.

miceri

Yeah that makes sense, and like you say an additional hole is probably going to double the cost. Hopefully I'll be able to avoid that.

It will definitely be undefloor heating on the ground floor, and probably radiators on the 1st floor. From what I understand these will have to be bigger than the norm, due to the lower heat output from the heat pump. Not too worried about that though.


The ground is quite hard about 1ft down, which is why I was thinking of going down the bore hole route. There's also a soakaway which could impede things via the trenching method.

There is a park which may available nearby, and apparently the ground isn't so hard there, so I'm hoping I'll be able to use that.

ham1sh

If you are thinking of mixing floor heating and radiators, then look carefully at which equipment you buy.

Floor heating temperature is significantly less than radiators. You will need a unit than is equipped to distribute 2 separate water flows. Otherwise, you risk damaging the under floor pipes.

The heat pump we got 'Nibe Fighter 1135' is prepared to do this, others are not - However, most have an optional uint you can buy to enable this. I would assume the plumber / installer would spec this out with you first.

Think about where the pump will be placed also, the Nibe range has a relatively noisy compresssor, but we have ours hidden in room that in effect 'swallows' this noise. Other rooms, especially next the bedrooms are not so lucky.

My neighbour did his at the same time as us, and choose a Bosch system, as it was quieter, because it was to be placed nearer to the lounge. Had a lower COP value though...

Are you thinking of having an 'all in one' unit, where the water tanks in enclosed with the pump unit? As we dimensioned for 4 people, 2 showers, 1 bath, 1 corner spa, then we choose the smaller stand alone pump, and a separate larger water tank.

m4rky_m4rk

Thanks again miceri, I never knew that, but I suppose it makes sense when you think about it.

We will be installing the pump in the garage, so hopefully noise won't be too much of a problem, but I'll keep this in mind when I eventually choose which system to go for.

We will be going for a separate water tank as well. We have 2 young kids  at the moment, and with all the baths and showers etc we tend to use quite lot of hot water. The washing machine seems to be running all day every day!

ham1sh

Heat pumps are quite popular here in Austria. The bore hole type seem to be more in favour at the moment with my Austrian friends. I think because of the smaller foot print in the garden and possible issues with future building work. It also avoids any issues with chilling plant roots. If its a new build I believe they can be placed beneath the house.  I think the ground conditions also influence the choice. The wetter the better for more efficient heat transfer.

I have also seen heat pumps here that extract heat from directly the outside air. The process can be reversed in the summer to provide a form of air conditioning.

johntheexpat

From what i've been told, the plant roots should be completely unaffected if the system has been designed properly. If done correctly you should never be taking more heat from the ground that what can be naturally replaced. If not designed/installed correctly then you can start to draw too much heat out and cause freezing.

I'm not intending doing any future building work, but having enough space in the garden for all the trenches could be an issue.
I would prefer to have the bore hole type, but they are quite a bit more expensive to install. If that's the only option I have though, then so be it.

A guy from Danfoss showed me this type of system, but I didn't like the idea of having a big ugly box stuck to the side of my house. He did say that they can be installed in an outbuilding or something instead, but i don't have any unfortunately.
Overall it looked like quite a good system, but i'd imagine after a few years it would start to look a bit shabby, due to weathering.

johntheexpat

Can you guys help please?

We have recently installed 2 x 10KW Danfoss (Eco) ground source units - we have 800mtrs of loops on single phase. The house is a 400 year old renovation (completed by ourselves) and has single glazing (listed) but very highly insulated. We installed energy meters to monitor input and output of both units.

Sice commisioning last August we have nonitored COP and seen figures from 2.9 to 3.4.

The sales literature from Danfoss was very clear for every 1 unit of energy used (input) you will get 3 free units for 25 years life. We have this documented and with the contracts.

We have had a number of meetings with Danfos and various engineers apointed by them and asked them to show how we get the 3 free units (COP 4) - they have been unable to do so and have not advised us of anything we have done wrong in installation or design.

I believe this is miss selling and should be covered under the sale of goods act - we have engaged solicitors and are looking at a significant claim over the 25 years at a reduced efficiency.

Has any one had similar statements or COP performance and seen undeliverable claims?

What can be done to resolve this?

Any ideas welcome.