Bentonite thermally enhanced grout

badgerhowlin

Hi,

I am getting 2 bore holes dug 90meters.

The company that are selling me the heat pump are pushing for me to put Bentonite thermally enhanced grout down each hole.

My drilling contractor that i know well has said that there is no Rule that i need this. he has said that it will be Very expensive to put this down it. He has done many whole and one one person has gone with this all the rest of them have just filled the bore hole with water.

What do people think? is it worth it.

Condenser

badgerhowlin wrote: »

Hi,

I am getting 2 bore holes dug 90meters.

The company that are selling me the heat pump are pushing for me to put Bentonite thermally enhanced grout down each hole.

My drilling contractor that i know well has said that there is no Rule that i need this. he has said that it will be Very expensive to put this down it. He has done many whole and one one person has gone with this all the rest of them have just filled the bore hole with water.

What do people think? is it worth it.

You'll need to grout to a few meters below the water line at least. The water will give you conductivity and a return of about 60-65w per meter. Where there is no water the probes will be just hanging in mid air and giving no return. In Europe they grout each hole to the bottom because of legal regulations and also the fact that ground water is usually much lower than here in Ireland.
Don't let your driller fob you off with pea gravel or any other crap like that. Grout to below the water line and your bore will be fine. Most drillers don't have the equipment so like to avoid doing it if they can get away with it. Also use the powder grout rather than the nugget type. You get far better contact.

Supertech

Have had a similar conversation with borehole contractor recently. He advised using grouting tubes bored in at the same time as the borehole. This allows for grouting the borehole from top to bottom at a later stage if the need arises (if performance reduces or if grouting becomes the norm) He also made the point that European installers are obliged to grout each hole by the way. Furthermore, he pointed out that the tubes are negatively marked, so they're also a good way to guarantee the depth of the borehole (provided you see them going in of course )

My guy has also told me that there is no hard and fast rule at the moment. His point which is valid I suppose was that if the tubes aren't in there's no way to grout them afterwards. Our attitude was better safe than sorry. Thoughts anyone - big house and deep holes >120metres each!!

Condenser

Supertech wrote: »

Have had a similar conversation with borehole contractor recently. He advised using grouting tubes bored in at the same time as the borehole. This allows for grouting the borehole from top to bottom at a later stage if the need arises (if performance reduces or if grouting becomes the norm) He also made the point that European installers are obliged to grout each hole by the way. Furthermore, he pointed out that the tubes are negatively marked, so they're also a good way to guarantee the depth of the borehole (provided you see them going in of course )

My guy has also told me that there is no hard and fast rule at the moment. His point which is valid I suppose was that if the tubes aren't in there's no way to grout them afterwards. Our attitude was better safe than sorry. Thoughts anyone - big house and deep holes >120metres each!!

I've pretty much said it all above but regarding his point about confirming the depth of the probe, the length of the probe is printed on the side of it at 1m intervals, so you can see exactly what length the probe in the ground is.

He's right that you can't regrout after a period of time has passed as its most likely that sections of the bore will have collapsed.