Air Souce v Ground Source (Bore hole) ££

DeeJunFan

Hi,

I have been focusing on simply Air Source Heat pump for a while now as my site is fairly tight on space and considered bore holes to expensive.

I'm building in Northern Ireland and recently there have been changes to grants etc which are making the calculations a bit more complicated.

Eg.

Grant for Heat Pump

Air Source - £1700
Ground Source - £3500

RHI payments for 7 years (estimated as not yet confirmed)

Air Source - £500
Ground Source - £1200

So far have been quoted around 6.5k for the Air Source Pump and 11K for the Ground source pump so after the grant it works out

Cost
Air Source - £4800
Ground Source - £7425

Deduct the estimated RHI yearly payments

Net Cost (Over 7 Years)
Air Souce - £4800 - 500*7 = £1300
Ground Source - £7425 - 1200*7 = £-975

Which leaves the Ground Source pump £2275 Cheaper over the first 7 years (not taking into account running costs)

The only unknown at the minute is the bore hole?

How much do you think would be an expected cost for good Bore holes?

Also would you consider the running cost savings to more than offset the cost of bore holes? I haven't looked into the Ground Source heat pumps all that much. Would there be any issue with supplying Domestic Hot water from a ground source pump?

Thanks in advance.
Damian

declan52

Boreholes are expensive ( used to drill them ). it all depends on the ground conditions at your site. Might be too sandy, not enough water strikes, might be shallow rock making it way more expensive. But you only know when the hole is drilled so its a bit of shot in the dark. Hole is priced per metre plus transport costs setting up costs loads of extras so beware.

DeeJunFan

Thanks for that.

Do you think there is anyway to get a rough cost? Would i be able to estimate the cost based on any boreholes drilled nearby? Not sure if there are any but i could try and find out.

If the borehole remains an unknown quantity then i wouldn't be to confident going ahead with it.

Are ground source heat pumps that much better?

Cheers
D

declan52 wrote: »

Boreholes are expensive ( used to drill them ). it all depends on the ground conditions at your site. Might be too sandy, not enough water strikes, might be shallow rock making it way more expensive. But you only know when the hole is drilled so its a bit of shot in the dark. Hole is priced per metre plus transport costs setting up costs loads of extras so beware.

declan52

Prob upwards of 6 grand depending on how deep the hole goes. Have a look on google for the geological map for your area to see what is there. Gives a rough clue of what to expect. Or if somebody close by has drilled even better. Phone a few of the companies that do gshp and they will be able to give you a better price. I looked at both but have ended up going for a biomass system. All depends on your own house construction in terms of insulation, orientation, doors and windows to how much heat you will need to determine type of heating.

DeeJunFan

Thanks Declan,

Spoke to a local installer today and he said 7K (sterling) would be a ball park. Hard to know people on here seem to have got much more competative quotes but i think there is a lot of granite around where i am building (Mourne Mountains)

I don't think the sums add up if you add that kind of money for borehole compared to Air Source.

D

declan52 wrote: »

Prob upwards of 6 grand depending on how deep the hole goes. Have a look on google for the geological map for your area to see what is there. Gives a rough clue of what to expect. Or if somebody close by has drilled even better. Phone a few of the companies that do gshp and they will be able to give you a better price. I looked at both but have ended up going for a biomass system. All depends on your own house construction in terms of insulation, orientation, doors and windows to how much heat you will need to determine type of heating.

declan52

DeeJunFan wrote: »

Thanks Declan,

Spoke to a local installer today and he said 7K (sterling) would be a ball park. Hard to know people on here seem to have got much more competative quotes but i think there is a lot of granite around where i am building (Mourne
I don't think the sums add up if you add that kind of money for borehole compared to Air Source.

D

granite is pretty hard but can be drilled. Done a gd few holes in mayobridge. Hard on the drill rig. Cost all depends on how much they want the job. Its a lot of money to be out but suppose over the life time of a house you should make it back if all the sales speak is to be believed!!

DeeJunFan

declan52 wrote: »

granite is pretty hard but can be drilled. Done a gd few holes in mayobridge. Hard on the drill rig. Cost all depends on how much they want the job. Its a lot of money to be out but suppose over the life time of a house you should make it back if all the sales speak is to be believed!!

Mayobridge is where I'm building so i will have to ask around and see who has it done and how much it cost.

As you say can the sales pitch be believed?

D

declan52

DeeJunFan wrote: »

Mayobridge is where I'm building so i will have to ask around and see who has it done and how much it cost.

As you say can the sales pitch be believed?

D

It was in and around the landfill site we drilled. As it was an old quarry the rock was sticking out of the ground. I am sure the surrounding area isn't much different. Its all about who you believe the most, I was for a borehole at the start then air source as the ground at my site is all sand. Done a bit of research into ashp and don't believe all the COP information. You used to be able to see live info of a few installations on the Mitsubishi site and wasn't convinced on how efficient they are to run. Might be better in a few years. That's why I went for biomass. They are not without there problems either but have to pick one and that's what I went for.

DeeJunFan

I know where you are talking about. about a mile away maybe but not that far. I would say all the ground around there is the same. Lot of mountains and lots of stone.

As for the air source i don't think the figures are wrong i just think the way the are put across is wrong as they dont include things like defrost cycles which can be very expensive on very cold days.

My sister went air source and is really happy with it but still would like to explore all the options myself.

how do you find the biomass? What are you burning, how is it delivered/stored etc?

Thanks
D

declan52 wrote: »

It was in and around the landfill site we drilled. As it was an old quarry the rock was sticking out of the ground. I am sure the surrounding area isn't much different. Its all about who you believe the most, I was for a borehole at the start then air source as the ground at my site is all sand. Done a bit of research into ashp and don't believe all the COP information. You used to be able to see live info of a few installations on the Mitsubishi site and wasn't convinced on how efficient they are to run. Might be better in a few years. That's why I went for biomass. They are not without there problems either but have to pick one and that's what I went for.

declan52

DeeJunFan wrote: »

I know where you are talking about. about a mile away maybe but not that far. I would say all the ground around there is the same. Lot of mountains and lots of stone.

As for the air source i don't think the figures are wrong i just think the way the are put across is wrong as they dont include things like defrost cycles which can be very expensive on very cold days.

My sister went air source and is really happy with it but still would like to explore all the options myself.

how do you find the biomass? What are you burning, how is it delivered/stored etc?

Thanks
D

am installing a pellet stove. Not in yet only on first fix on my build. Will use bagged pellets till I get a shed built to store a few tonne in. At least you can see your sisters in action and see how it performs in a house. Hard to beat seeing a system in action. A few of my friends have a pellet system installed and are more than happy and their houses wouldn't be the best in terms of airtightness and insulation.