Ground Source Heat Pumps

edwh

Thanks for these calculations. Very useful.

I'm not looking at this primarily as a cost-saving measure in the short-term, or worried about the opportunity cost of what else I could do with the money (though I appreciate that this is MSE). It's partly environmental concerns, and partly long term - I'm expecting grid energy to shift to lower carbon sources, and domestic oil to get increasingly expensive.

If it reduces cost a little in the short term, that's great; if it increases them noticeably then that's bad.

The calculations so far (which are obviously finger in the air and need a proper survey) suggest that it's probably worth going to the next step of getting someone in to quote.

lovesgshp

edwh wrote: »

It's 316 M2, though we might not use all of that in winter.

Existing bills according to the EPC are:
- £500 over 3 years for lighting
- £7353 over 3 years for heating
- £594 over 3 years for "hot water"

The heating might be on the high side because they currently heat a conservatory for plants, which would be disastrous in terms of efficiency. The EPC estimates we could save:
- £1500 over 3 years by room-in-roof insulation
- £303 over 3 years by cavity wall insulation
- £633 over 3 years by extra wall insulation (but at great cost)

I obviously cannot quote on the lighting saving, so please excuse me for that.
With a normal GSHP, then the breakdown between heating and DHW is about 20% DHW to 80% heating. That heating requirement over the 3 years is very high
Ok, for a 316m2 property, we would estimate normally, without the thermal data @ approx a 17kwh output pump with normal insulation levels. With higher insulation, probably down to 14Kwh output.
I do not think you will get that much further below for the size of the property and age.
The figures that you have quoted from the EPC, seem quite high, as energy costs in the UK are far lower than here and they seem to be about the same as someone from here would pay for 3 years.
Analysing a little further, you can reduce the GSHP heating circuit by 30% in rooms that do not need constant heating.
HTH

lovesgshp

I think if you are going for a GSHP, then you would be probably in the 20k euro area with the excavations etc, depending on the size of the pump.
Expect 2x 120 mtrs plus excavations for the 17kw unit, or 112 mtrs for the 14kwh unit.

AL0104

Hello,

I've been reading the threads on GSHP & ASHP here for a while & found a great deal of useful information. I wonder if anyone could help answer what might possibly be a daft question?

My situation is that I'm currently building a new house in a rural part of Cornwall & want to install a heat pump for all heating & hot water. Ideally I'd go for ground source however with relatively limited gardens (approx 700 sq. m) all the quotes I've had call for an 8k system with two 100m boreholes - not cheap!

The thing is we already have a new borehole (32m deep) for our water supply, plus an older well (8m approx) that both yield large amounts of water. Would it not be possible to utilise those water sources for a heat pump system? Is there any way a closed-loop system can share a borehole with one for drinking water? If not, since we know there is so much water at 30m depth, couldn't a more economical "water source" heat pump system be designed using shallower boreholes?

lovesgshp

AL0104 wrote: »

Hello,

I've been reading the threads on GSHP & ASHP here for a while & found a great deal of useful information. I wonder if anyone could help answer what might possibly be a daft question?

My situation is that I'm currently building a new house in a rural part of Cornwall & want to install a heat pump for all heating & hot water. Ideally I'd go for ground source however with relatively limited gardens (approx 700 sq. m) all the quotes I've had call for an 8k system with two 100m boreholes - not cheap!

The thing is we already have a new borehole (32m deep) for our water supply, plus an older well (8m approx) that both yield large amounts of water. Would it not be possible to utilise those water sources for a heat pump system? Is there any way a closed-loop system can share a borehole with one for drinking water? If not, since we know there is so much water at 30m depth, couldn't a more economical "water source" heat pump system be designed using shallower boreholes?

Hi and welcome to the discussions.
A 8Kwh output pump, would probably need 2 x 90mtr approx excavations, so with 700m2 of garden area you should be able to do that. If not then go for compact collectors which are far cheaper than a borehole.
http://www.plumbcenter.co.uk/en/renewables/ground-source-heat-pumps/worcester-bosch-greenstore-heat-pump-compact-collector-16770
The well at that depth would be too shallow and therefore not suitable.
HTH

AL0104

Thanks very much - I hadn't considered compact collectors before. Looking at the specs though they seem to suggest that you need twice as many if you don't plan on recharging the ground using air recovery systems (which we don't). If that was the case & we needed 20-25 compact collectors for an 8Kwh system that would seem more costly than the borehole option. Shame we can't make use of all the water we have 30m below our garden though.

lovesgshp

AL0104 wrote: »

Thanks very much - I hadn't considered compact collectors before. Looking at the specs though they seem to suggest that you need twice as many if you don't plan on recharging the ground using air recovery systems (which we don't). If that was the case & we needed 20-25 compact collectors for an 8Kwh system that would seem more costly than the borehole option. Shame we can't make use of all the water we have 30m below our garden though.

Yes, without the heat recovery system, you would need twice as many panels, as the heat loss through the collectors does not give a suitable recharge time.
I still think, that with your ground area, you could still have a conventional layout. Pity you cannot send a scale drawing!!

akmodi

Hi,

I have an E11 Iceenergy (from IVT) heat pump -- which is to small for my house. Thus a large amount of top up is used from additional heat source.

We have Gas at the house, a boiler can be installed.

Does anyone have any experience of adding a gas boiler at the peak demand times to take the additional burden ? How is this controlled /fed etc ?

These are called bi-valent systems, but how can one convert a GSHP to this?

Thanks

lovesgshp

akmodi wrote: »

Hi,

I have an E11 Iceenergy (from IVT) heat pump -- which is to small for my house. Thus a large amount of top up is used from additional heat source.

We have Gas at the house, a boiler can be installed.

Does anyone have any experience of adding a gas boiler at the peak demand times to take the additional burden ? How is this controlled /fed etc ?

These are called bi-valent systems, but how can one convert a GSHP to this?

Thanks

Hi Akmodi.
Yes, you can have a gas system as a back-up.
Just a few questions though as I have a E11 like yourself.
You say it is too small for your house, so how many m2 is the house?
Rads or underfloor, and if rads is there a buffer tank?
What temps are you setting for heating/dhw?
Go into the K2 menu and let me know the readings from #7 (7.1-7.4), and also from #11 (Alarms).
Edit: Also how long has the pump been installed?

lovesgshp

Akmodi
If you can give me the answers to the questions that I asked above, then I will give you my thoughts on the existing system, as you may not need to go to the extra expense of adding the gas supply.
If you do not know how to get into the K2 menu, then hold the "HEAT" button down for about 10-15 secs.