Ground Source Heat Pumps

Cardew

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/48204/3307-acoustic-noise-air-source-heat-pumps-1.pdf


1.3 Potential noise created by these systems has often been highlighted as a


restricting factor at planning stages and often required expensive acoustic


assessments.


1.4 There is little data available on the actual noise level of ASHP units when


installed on real sites. Instead, designers, planners and customers have had to


rely on manufacturers’ performance claims, which are typically based on lab


testing in ideal conditions.

lovesgshp

Many thanks Cardew, I think that with the link that you clarified what I was trying to put simply into even more detail.

edwh

I'll be moving into a property which currently has oil heating, and want to look at renewable options. Bear with me, because these are newbie questions.

The property is old (probably C18th), with walls that are about 50cm thick but without cavity insulation in most of it. The floors are solid and therefore underfloor heating would be very disruptive to retrofit. It has decent double-glazing; loft insulation could definitely be improved, and that's clearly a priority.

The questions I have are mostly about what things I can and can't do in combination, and phasing - partly because we want to cultivate some of the land where the GSHP might go and therefore don't want to dig it all up in the wrong order.

1) Can I fit a GSHP and retain the existing oil heating as a backup? That would avoid the risk of suddenly having massive electricity bills. I've come across scare stories, and though we have reasonable assets we don't have a great income, so while I can plan for capital expenditure I don't want to risk high ongoing costs.
2) I understand that GSHPs work better when you replace the radiators. Is it remotely sensible to consider doing this in two stages, i.e. installing it and seeing how it goes and then replacing the radiators later?
3) There is a stream running through the land, about 20ft below the height of the house. It's a couple of metres wide, not more than a foot or two deep, with a reasonable flow year round. Is it worth considering a water source heat pump, or do you really need a deep lake for this?
4) We probably can't do roof-mounted PV cells, but we have enough room that we could do a lot of ground-mounted ones if that was sensible. Would I be kidding myself if I thought that we could offset some of the running costs of the GSHP in this way?
5) I've seen some suggestion that you can pump heat back into the ground from solar during the warmer months. Could someone expand on the pros and cons of this?

Finally, this is in the Ribble Valley/Bowland area, so any recommendations for or against local suppliers would be useful.

Thanks very much for reading, and for any help you can offer, as I start to navigate this complex area.

jackyann

fluffymuffy wrote: »

Crazy Prices !

I just put my data in - house age/size etc and it told me ....
- a ground source heat pump installation would cost £72,109.51

- an Air Source heat pump would cost £18,776.16

I've just installed my own for £580. OK it's only 5.2kw. Perhaps the one quoted has a higher output. I could install 4 for £2K. That would be warm enough to compare.

If you don't mind, I'd be interested to know what the co-efficient of efficiency is (and have you had it in long enough to check if what you are actually getting?)
Thanks

jackyann

edwh wrote: »

I'll be moving into a property which currently has oil heating, and want to look at renewable options. Bear with me, because these are newbie questions.

The property is old (probably C18th), with walls that are about 50cm thick but without cavity insulation in most of it. The floors are solid and therefore underfloor heating would be very disruptive to retrofit. It has decent double-glazing; loft insulation could definitely be improved, and that's clearly a priority.

The questions I have are mostly about what things I can and can't do in combination, and phasing - partly because we want to cultivate some of the land where the GSHP might go and therefore don't want to dig it all up in the wrong order.

1) Can I fit a GSHP and retain the existing oil heating as a backup? That would avoid the risk of suddenly having massive electricity bills. I've come across scare stories, and though we have reasonable assets we don't have a great income, so while I can plan for capital expenditure I don't want to risk high ongoing costs.
2) I understand that GSHPs work better when you replace the radiators. Is it remotely sensible to consider doing this in two stages, i.e. installing it and seeing how it goes and then replacing the radiators later?
3) There is a stream running through the land, about 20ft below the height of the house. It's a couple of metres wide, not more than a foot or two deep, with a reasonable flow year round. Is it worth considering a water source heat pump, or do you really need a deep lake for this?
4) We probably can't do roof-mounted PV cells, but we have enough room that we could do a lot of ground-mounted ones if that was sensible. Would I be kidding myself if I thought that we could offset some of the running costs of the GSHP in this way?
5) I've seen some suggestion that you can pump heat back into the ground from solar during the warmer months. Could someone expand on the pros and cons of this?

Finally, this is in the Ribble Valley/Bowland area, so any recommendations for or against local suppliers would be useful.

Thanks very much for reading, and for any help you can offer, as I start to navigate this complex area.

can really only help with the water suggestion - when I looked a couple of years ago, you needed a 2 metre drop

Cardew

edwh wrote: »

I'll be moving into a property which currently has oil heating, and want to look at renewable options. Bear with me, because these are newbie questions.

The property is old (probably C18th), with walls that are about 50cm thick but without cavity insulation in most of it. The floors are solid and therefore underfloor heating would be very disruptive to retrofit. It has decent double-glazing; loft insulation could definitely be improved, and that's clearly a priority.

The questions I have are mostly about what things I can and can't do in combination, and phasing - partly because we want to cultivate some of the land where the GSHP might go and therefore don't want to dig it all up in the wrong order.

1) Can I fit a GSHP and retain the existing oil heating as a backup? That would avoid the risk of suddenly having massive electricity bills. I've come across scare stories, and though we have reasonable assets we don't have a great income, so while I can plan for capital expenditure I don't want to risk high ongoing costs.
2) I understand that GSHPs work better when you replace the radiators. Is it remotely sensible to consider doing this in two stages, i.e. installing it and seeing how it goes and then replacing the radiators later?
3) There is a stream running through the land, about 20ft below the height of the house. It's a couple of metres wide, not more than a foot or two deep, with a reasonable flow year round. Is it worth considering a water source heat pump, or do you really need a deep lake for this?
4) We probably can't do roof-mounted PV cells, but we have enough room that we could do a lot of ground-mounted ones if that was sensible. Would I be kidding myself if I thought that we could offset some of the running costs of the GSHP in this way?
5) I've seen some suggestion that you can pump heat back into the ground from solar during the warmer months. Could someone expand on the pros and cons of this?

Finally, this is in the Ribble Valley/Bowland area, so any recommendations for or against local suppliers would be useful.

Thanks very much for reading, and for any help you can offer, as I start to navigate this complex area.

I am sure 'lovesgshp' will be along soon and give expert advice; and as he lives and works in Italy has no vested interest in getting a sale!


I take it you have read the Energy Saving Trust trial report on both GSHP and ASHP here. http://www.energysavingtrust.org.uk/Organisations/Working-with-Energy-Saving-Trust/The-Foundation/Our-pioneering-research


This details the second 12 month trial to overcome the results of the first trial which were 'disappointing'.


You will see that the average SPF(System Performance Factor) was 2.82. So if your electricity cost is, say, 12p/kWh the effective cost of GSHP heating is 4.26p/kWh.


You could have a higher, or lower, SPF than 2.82; but that figure was only achieved with a lot of 'interventions'(improvements) by manufacturers.


Oil currently cost just under 6p/kWh but you have to take into account the efficiency of the boiler. That could mean paying effectively between 6p/kWh for a really modern boiler to around 8p/kWh for an old boiler.


Given that a GSHP will cost at least £20,000, you will need huge consumption to make a GSHP a financial proposition. If you use, say, 30,000kWh a year for heating and hot water(double the UK average) your savings will be between £600 and £1,200 pa. Against that you need to offset the interest of £20,000 in a long term saving account earning 3%?? = £600 a year.


So in my opinion, even if your house is found suitable for a GSHP, in financial terms it is a non-starter.

lovesgshp

edwh wrote: »

I'll be moving into a property which currently has oil heating, and want to look at renewable options. Bear with me, because these are newbie questions.

The property is old (probably C18th), with walls that are about 50cm thick but without cavity insulation in most of it. The floors are solid and therefore underfloor heating would be very disruptive to retrofit. It has decent double-glazing; loft insulation could definitely be improved, and that's clearly a priority.
Can you give the M2 of the area to be heated, as this helps to get a idea of the pump size you may need? We have many 200+ year old houses that have either retrofit or new installs.

The questions I have are mostly about what things I can and can't do in combination, and phasing - partly because we want to cultivate some of the land where the GSHP might go and therefore don't want to dig it all up in the wrong order.
Depending on the above answer, then we can estimate the length of the above excavations required, if you are going for a horizontal system. Most are circa 1.2 mtrs deep, so no problem for small shrubs etc. No large deep rooted trees are advised though over the lines

1) Can I fit a GSHP and retain the existing oil heating as a backup? That would avoid the risk of suddenly having massive electricity bills. I've come across scare stories, and though we have reasonable assets we don't have a great income, so while I can plan for capital expenditure I don't want to risk high ongoing costs.
As a retrofit, then you can have the oil system as a backup if required.
2) I understand that GSHPs work better when you replace the radiators. Is it remotely sensible to consider doing this in two stages, i.e. installing it and seeing how it goes and then replacing the radiators later?
That is not always true, as usually with a radiator system then there would be a buffer tank fitted and the heating curves for the GSHP adjusted for them. Remember that the temperature flow to the rads will normally be about 50C, but it will be a more stable heat and at a fairly constant level. Another alternative if you do not find it suitable, would be the installation of fan coils to replace the rads. Another advantage of the fan coils, is that you can use them to cool the house in the "hotter" Summer months if needed.
3) There is a stream running through the land, about 20ft below the height of the house. It's a couple of metres wide, not more than a foot or two deep, with a reasonable flow year round. Is it worth considering a water source heat pump, or do you really need a deep lake for this?
Too shallow
4) We probably can't do roof-mounted PV cells, but we have enough room that we could do a lot of ground-mounted ones if that was sensible. Would I be kidding myself if I thought that we could offset some of the running costs of the GSHP in this way?
Yes, if you are getting the feed in tariff, but only on good days in the winter. Remember the pump will be running at higher levels in the winter.
5) I've seen some suggestion that you can pump heat back into the ground from solar during the warmer months. Could someone expand on the pros and cons of this?
You will not increase the ground heat level that much in the summer months. The input temp here is +20C in the summer from the ground loops, so you will not achieve that much more. In the winter, then you will have a advantage, but you need the heat to go to the ground loop and not heat the earth.

Finally, this is in the Ribble Valley/Bowland area, so any recommendations for or against local suppliers would be useful.

Thanks very much for reading, and for any help you can offer, as I start to navigate this complex area.

Hope these answers help. Sorry I cannot advise on any companies in your area, but hope someone in the forum will do so. Before doing anything, make sure that the full thermal needs of the property are calculated by the contracting company.
I can give you a maximum idea of what I think, if you let me know house size etc.

edwh

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)

jackyann

Cardew wrote: »

I am sure 'lovesgshp' will be along soon and give expert advice; and as he lives and works in Italy has no vested interest in getting a sale!


I take it you have read the Energy Saving Trust trial report on both GSHP and ASHP here. http://www.energysavingtrust.org.uk/Organisations/Working-with-Energy-Saving-Trust/The-Foundation/Our-pioneering-research


This details the second 12 month trial to overcome the results of the first trial which were 'disappointing'.


You will see that the average SPF(System Performance Factor) was 2.82. So if your electricity cost is, say, 12p/kWh the effective cost of GSHP heating is 4.26p/kWh.


You could have a higher, or lower, SPF than 2.82; but that figure was only achieved with a lot of 'interventions'(improvements) by manufacturers.


Oil currently cost just under 6p/kWh but you have to take into account the efficiency of the boiler. That could mean paying effectively between 6p/kWh for a really modern boiler to around 8p/kWh for an old boiler.


Given that a GSHP will cost at least £20,000, you will need huge consumption to make a GSHP a financial proposition. If you use, say, 30,000kWh a year for heating and hot water(double the UK average) your savings will be between £600 and £1,200 pa. Against that you need to offset the interest of £20,000 in a long term saving account earning 3%?? = £600 a year.


So in my opinion, even if your house is found suitable for a GSHP, in financial terms it is a non-starter.

When we were looking at this, the Centre for Alternative Technology advised us that (finance aside) it was really only worth installing a heat pump with a co-efficient of efficiency greater than 4. Below that, the return doesn't offset the "dirtiness" of the electricity. I know that manufacturers are now claiming better efficiency, but the Energy Saving Trust does put it into perspective!

We are very pleased with our Mechanical Heat Recovery & Ventilation pump, but we live in a very well insulated house (which is really the best place to begin!)

Cardew

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)

On a money saving website it is relevant to look at the financial issues involved.


In round figures the EPC states £8000 for 3 years heating and lighting, but can be reduced to £6000 by the first two items of insulation(£1,500 and £303)


The cost effectiveness of the £633 is for you to decide.


So £2,000 a year with oil CH and that includes heating a conservatory for plants.


The average cost of CH oil today is 57p a litre. So £2,000 will supply 3,500 litre, i.e approx. 35,000kWh. (1 litre = 10kWh)


What we don't know is the efficiency of the oil boiler, which could be between 65% and 95%; which we need to know to calculate the 'delivered' kWh. If we take the mid-point of 80%, that equates to 28,000kWh.


If your GSHP achieved the average SPF(sometimes called COP)of the EST trial of 2.82 it would require 9,930kWh electricity. This at 12p/kWh will cost approx. £1,200 pa.


So your headline savings could be in the region of £800 a year. However as stated earlier if the GSHP cost £20,000, that sum invested in a long term bank account could earn £600 in interest(indeed the best rate offered is 5% gross for a 10 year bond)


Now admittedly the above is based on 'back on an envelope calculations' but it is IMO a decent stab at the economics.


Obviously there are a huge number of unknowns.


1. Firstly is your house suitable for a heat pump?


2. Would it achieve a SPF of 2.82 - higher or lower?


3. Would a GSHP cost £20,000


4. RHI subsidies - how much?


5 Oil Boiler efficiency?


6 Will you heat the conservatory - and if not, what would that save.


7. Given that a GSHP has to run for much longer than an oil CH boiler, it will be required to run for some of the time while you are out of the house and in bed.


Decisions, Decisions!