Gerthermal vertical borehole costs

rodge123

Created this thread from here but got no reply....though I might have better luck here. (Not sure how to move a Thread).

I've got a quote for Heat Pump and UFC to use as a PC sum in tendering documents.
But the following was noted in the quote:
- Price excludes ‘0-Heat-Loss’ pipe if unit located away from dwelling.
- Trench excavation or bore hole drilling excluded from geothermal quotation.

So my questions:
1: Is it normal for a company to not drill the borehole as part of the HP/UFC installation?
2: How much are the boreholes likely to cost? (250m2 building to heat on 0.6acres, horizontal layout not option due to septic tank/well/other building on site.)

Any other tips/advice welcome

Thanks

Builder Ben

If you have a long site or long lane way in it may be possible to a a long, narrow ground source collector.
Otherwise, allow about €38-€45 per vertical metre drilled. In general you will be looking at a depth of around 70-100 metres.

murphy31ie

38 to 45 a metre, are you serious. I will pm anyone a company that does it for 25 to 28 a metre

rodge123

murphy31ie wrote: »

38 to 45 a metre, are you serious. I will pm anyone a company that does it for 25 to 28 a metre

Could you pm that company murphy?

Thanks

hexosan

I got quoted €20 per metre. I'd love to know who's charging €38-€45 thats laughable.

Builder Ben

They were prices I got quoted including the grout pipes etc....

Calahonda52

Builder Ben wrote: »

They were prices I got quoted including the grout pipes etc....

these numbers are better quoted either:
for an estimated depth rather than in per metre because it creates an expectation that the depth is a budget variable rather than a design requirement, so if all in at 45 a metre, quote between 3500 and 4500 for depths between 75 and 100.
or
so much for turning up and X euro a meter after that subject to a minimum number.
This avoids the problem of quoting and charging for 100 and only drilling 25.

Condenser

hexosan wrote: »

I got quoted €20 per metre. I'd love to know who's charging €38-€45 thats laughable.

Anyone doing it right won't get away with charging less than €30 per metre. By the time you take probe, grout, drill bits, diesel and the cost of the €300,000 pieces of equipment on site you can be damn sure anyone doing it for less is a chancer.


Your borehole depth is dependant on the cooling capacity of the heat pump divided by the expected return per metre from the bore. So for example if you had a 10kw heat pump and the electrical load was 2kw then it would have a cooling capacity of 8kw. If you were drilling in limestone a return of 45w per linear metre would not be unreasonable. So 8000W divided by 45W equals roughly 178m so you would be looking for 180m of bore or 2 x 90m ideally. Anything above the 45w should be considered a bonus that will add to performance.


Unfortunately most things in this country come down to a price war and the quality of the service or the product gets forgotten about. In Germany or Europe in general getting good boreholes properly completed cost in the region of €45 to €55 per metre and they have all the equipment required just a days shipping away. Everything here needs to be imported so anyone doing it for below €30 is cutting corners everywhere they can.

Calahonda52

Good analysis!
In passing, in this brave new world of certification:
who signs off on

1. actual depth drilled?
2. expected energy output from the holes

Condenser

Calahonda52 wrote: »

Good analysis!
In passing, in this brave new world of certification:
who signs off on

1. actual depth drilled?
2. expected energy output from the holes

Its all pretty much falling on the installer/designers shoulders. If he has to contract in someone to do the drilling they better be damn sure it being done right. Its also a case of the installer interacting with the driller and discussing the conditions encountered. Just because there is a certain rock type in an area is a guarantee of nothing. Conditions change over very short areas. A bore with high water quantities is not equal to one with a trickle of water and the second should be grouted top to bottom. Complete grouting is not achievable in certain water stratas as it will get washed away. Your driller needs to be adaptable to differing conditions and have the equipment to deal with it. Drilling requires more than just drilling a hole and dropping a pipe into it and at the end of the day it is the heat pump installer who has to certify the installation.
As with the case above if the supplier can't even supply the minimum recommended depth for the bore then its time to look elsewhere.

rodge123

Condenser wrote: »

Its all pretty much falling on the installer/designers shoulders. If he has to contract in someone to do the drilling they better be damn sure it being done right. Its also a case of the installer interacting with the driller and discussing the conditions encountered. Just because there is a certain rock type in an area is a guarantee of nothing. Conditions change over very short areas. A bore with high water quantities is not equal to one with a trickle of water and the second should be grouted top to bottom. Complete grouting is not achievable in certain water stratas as it will get washed away. Your driller needs to be adaptable to differing conditions and have the equipment to deal with it. Drilling requires more than just drilling a hole and dropping a pipe into it and at the end of the day it is the heat pump installer who has to certify the installation.
As with the case above if the supplier can't even supply the minimum recommended depth for the bore then its time to look elsewhere.

I know my brother in law backfilled their bore hole with gravel, they met water after a few meters.
I know our neighbours have a dug well and it has plenty of water at about 4 meters I believe.

Will this determine if we need to grout ? I.e. extra costs?

We have an existing bore hole well on site, could this provide us with useful data to use before any drilling of geo bore holes is done?

Calahonda52

rodge123 wrote: »

I know my brother in law backfilled their bore hole with gravel, they met water after a few meters.
I know our neighbours have a dug well and it has plenty of water at about 4 meters I believe.

Will this determine if we need to grout ? I.e. extra costs?

We have an existing bore hole well on site, could this provide us with useful data to use before any drilling of geo bore holes is done?

Backfilling with gravel is exposing the ground water aquifer to surface sources pollution such as animal waste and the like.

It is not the proper or environmentally correct way to do it but is typical of the Irish approach to doing anything right.

Condenser

rodge123 wrote: »

I know my brother in law backfilled their bore hole with gravel, they met water after a few meters.
I know our neighbours have a dug well and it has plenty of water at about 4 meters I believe.

Will this determine if we need to grout ? I.e. extra costs?

We have an existing bore hole well on site, could this provide us with useful data to use before any drilling of geo bore holes is done?

More cowboy solutions. Like a bird dropping a stone into a bottle trying to raise the level of the water. You need to grout to the first significant water ingress i.e. a flow of water that would wash away the grout if you tried to grout deeper. Even a bore that has significant levels of water at the end but only a few litres entering at different levels should be grouted also. If you leave a bore with low water flows ungrouted the cold water sink to the bottom of the bore where it just plummets in temperature and affects overall performance. What ỳou described is the typical irish solution to an irish problem. Putting gravel in there only hindered the water flow and left the probe open to potential damage.

rodge123

Condenser wrote: »

More cowboy solutions. Like a bird dropping a stone into a bottle trying to raise the level of the water. You need to grout to the first significant water ingress i.e. a flow of water that would wash away the grout if you tried to grout deeper. Even a bore that has significant levels of water at the end but only a few litres entering at different levels should be grouted also. If you leave a bore with low water flows ungrouted the cold water sink to the bottom of the bore where it just plummets in temperature and affects overall performance. What ỳou described is the typical irish solution to an irish problem. Putting gravel in there only hindered the water flow and left the probe open to potential damage.

Sorry guys, he actually backfilled with soil/clay and finished off the top few meters with gravel.

Complete grouting is not achievable in certain water stratas as it will get washed away

What would you do in this case Condenser?

Do you have any recommend articles/links I could read to get up to speed on the proper way to install vertical borehole geothermal systems? (Just so I have a better chance of identifying cowboys when it comes to the build!)

I had a quick read of this which is easy enough to follow.

Condenser

[/quote="rodge123;96038903"]Sorry actually backfilled with soil/clay and finished off the top few meters with gravel.



What would you do in this case Condenser?

Do you have any recommend articles/links I could read to get up to speed on the proper way to install vertical borehole geothermal systems? (Just so I have a better chance of identifying cowboys when it comes to the build!)

I had a quick read of this which is easy enough to follow.[/quote]

That is the most random borehole backfill procedure I've ever heard off and completely unachieveable in terms of getting a fully filled bore with good thermal contact.

The correct proceedure for completing a geothermal bore is to case to solid rock, then continue drilling with the main string to the required depth. The main string should then be removed and a geothermal probe dropped (either a single loop 40mm or double loop 32mm) along with a grouting tremie pipe. The probe should be filled with water and pressure tested. A grouter should then be used to mix and pump the grout down the tremie pipe to fill the bore from the bottom up to avoid air pockets. When filled the casings should be removed to allow full contact with the bore over its entire length. The only exception to any of this is where water volumes are too high. A sponge or net should be set on the probe at the point just above the level of high water ingress and should be grouted from there up.
Any procedure apart from the above is a self styled version of what should actually happen either because the right equipment isn't available or lack of knowledge

Heres a good video of how its done properly http://youtu.be/w_nRoHTWu0s

rodge123

Thanks Condenser.

So the decisions on whether to grout all the bore depending on water flows is only decided on the day of the actual drilling?

Also, how can the Heat pump installer know what the minimum recommended depth should be before any holes are drilled? I.e. they dont yet know the soil/rock type composition?

Could you PM me the details of a few reputable companies you would recommend? (Drilling and HP Installers)

Do any companies provide HP and bore drilling service as one?