Open loop ground source heat pump.

[Oliver90owner]

The water pump (not heat pump) you would need to pump water out of the well at that depth and at the flow rates I was talking about would probably be completely unfeasible and / or uneconomic.


It may need c.150W to pump that volume over 12m. BUT, that is assuming only to lift to ground level, not taking into account extra lift and pipe losses, motor inefficiency, etc. Nor does it account for a further several metres lift if exhausting the suppply (expected).

At over ten metres, it would require a self priming pump or a submersible. I suspect, with all variables added as a worst scenario, a half horse power motor (or more?) may be necessary.

[AE-NMidlands]

The water pump (not heat pump) you would need to pump water out of the well at that depth and at the flow rates I was talking about would probably be completely unfeasible and / or uneconomic.

It may need c.150W to pump that volume over 12m. BUT, that is assuming only to lift to ground level, not taking into account extra lift and pipe losses, motor inefficiency, etc. Nor does it account for a further several metres lift if exhausting the suppply (expected).
At over ten metres, it would require a self priming pump or a submersible. I suspect, with all variables added as a worst scenario, a half horse power motor (or more?) may be necessary.

If you are returning water to the well (returning it to the underground reservoir) wouldn't it act like a syphon and save most of the energy?
You might need a semi-rigid pipe on the downflow for that to work, to stop it sucking itself flat.
A

[Oldgreybeard]

We have a well for our drinking water. The water sits about 11 metres down usually and we have a 600 watt submersible pump that pumps the water up to an accumulator tank that feeds the house. The pump can deliver around 30 litres per minute, I think. Might give an idea as to how much pump power is needed.

When I wanted to put extra wells in to run a heat pump I did some sums to find out how much water we needed to pump out and back, and the numbers looked like those that @Nowty has already given. In our case it looked as if we would need to pump more than the maximum allowed of 20,000 litres per day in cold weather, which would have meant getting a licence.

Unfortunately there isn't any sort of siphon effect when pumping water out, through a heat pump and then back down a well, and what's worse is that submersible pumps are inefficient, and use a lot more power than they should when lifting water out of a well. If we had decided to use wells and a GSHP, then I was planning to do a (far less heroic) version of @Nowty's civil engineering masterpiece, by putting some vertical loops of pipe deep into the well. That way I could have just used a circulating pump that uses a lot less power, as the weight of the water going down the pipe counterbalances the weight of water coming back up.

As an aside, I well remember following the tale of @Nowty's underground masterpiece. There were many times I looked at some of the photos of props etc through partly closed hands over my eyes, thinking that it was one of the most scary things I'd ever seen. Brilliant job in the end, though!

[nowty]

Have you had much of a problem with corrosion on those pipes?

Not yet.

They certainly are no longer shiny, but the ground loop is pressurised to about 1bar with a small expansion vessel, so a leak would be instantly noticeable.

[nowty]

As an aside, I well remember following the tale of @Nowty's underground masterpiece. There were many times I looked at some of the photos of props etc through partly closed hands over my eyes, thinking that it was one of the most scary things I'd ever seen. Brilliant job in the end, though!

That sounds like an excuse to post the scariest picture of all time.

For those don't know the saga, basically 8 years ago I found a sink hole under my house and driveway which was caused 40 years ago by the builder driving a concrete pile straight through a half metre diameter culvert (buried river in a pipe). Builder went bust years ago, insurance company said no damage to your property so its a maintenance issue, council said it was water company problem, water company said its not our pipe, finally Environment Agency told me its a river and its your responsibility as land owner to fix it. Several contractors refused the work as too unclear who was responsible for it and they did not want to get involved in any legal dispute. Environment Agency told me you could use our contractors but it will probably be cheaper to partially demolish and re-build your house.

So me and my lodger spent 6 months digging and repairing it ourselves. Total cost £5k and £1k of that was installing a water harvesting system.



Built a steel reinforced concrete bypass around the offending pile.



Now looks like this underground.



And like this at ground level.

[Tinbum]

Sink holes are great!

We have had a problem with flooding and a lot has been due to bad drainage. I've always known that our water goes under a main road from a dyke but had never seen the water going that way. The person we bought the house from said he'd never seen water going under the road and he'd lived here for 40 odd years. During the first lockdown I decided to investigate. Using some drain dye I found where the pipe exited into the next dyke which took about a day to work its way through. I then walked a straight line from that back to the culvert under the road and found this in the field.



I don't own the field and looking back on google maps it looks as if the farmer has just been ploughing over it for years. Further use of the dye showed it was connected to both ends of the pipes.

It took me ages to sort. The pipe had collapsed so had to be repaired. The culvert under the road, 3ft in diameter and about 20m long was totally full with silt etc and both man holes at each end were full, and they were about 12ft deep! I'd bought a vacuum tanker to go behind the tractor and an industrial diesel drain jetter and it took me over a week to get it all out.

part way though;


3ft culvert;

[spread-tee]

As an aside, I well remember following the tale of @Nowty's underground masterpiece. There were many times I looked at some of the photos of props etc through partly closed hands over my eyes, thinking that it was one of the most scary things I'd ever seen. Brilliant job in the end, though!

That sounds like an excuse to post the scariest picture of all time.

For those don't know the saga, basically 8 years ago I found a sink hole under my house and driveway which was caused 40 years ago by the builder driving a concrete pile straight through a half metre diameter culvert (buried river in a pipe). Builder went bust years ago, insurance company said no damage to your property so its a maintenance issue, council said it was water company problem, water company said its not our pipe, finally Environment Agency told me its a river and its your responsibility as land owner to fix it. Several contractors refused the work as too unclear who was responsible for it and they did not want to get involved in any legal dispute. Environment Agency told me you could use our contractors but it will probably be cheaper to partially demolish and re-build your house.

So me and my lodger spent 6 months digging and repairing it ourselves. Total cost £5k and £1k of that was installing a water harvesting system.



Built a steel reinforced concrete bypass around the offending pile.



Now looks like this underground.



And like this at ground level.

Aarrghh no Nowty, my nervous tic has come back

Desp

[daftlad]

Nowty, Spread-tee

My word, that's some serious DIY civil engineering!
I will post some pics in due course of some DIY civil engineering for changing the timbers holding my roof up (without taking the roof off)!
They are flogging pumps at the local bricodepot for 100€ on Thursday, think I will buy one and see how long it takes to empty the well?
The fact there are 2 wells on the property is maybe a sign that they will take ages to re fill, on the other hand it was an agricultural property so maybe they had to provide lots of water for animals?

Peas

[nowty]

Nowty, Spread-tee

My word, that's some serious DIY civil engineering!
I will post some pics in due course of some DIY civil engineering for changing the timbers holding my roof up (without taking the roof off)!
They are flogging pumps at the local bricodepot for 100€ on Thursday, think I will buy one and see how long it takes to empty the well?
The fact there are 2 wells on the property is maybe a sign that they will take ages to re fill, on the other hand it was an agricultural property so maybe they had to provide lots of water for animals?

Peas

I was thinking, if your hell bent on doing it open source from one well into another, you could do it in such a way that every hour or so, you reverse flow the water, that way you never empty a well and that would give you heat replenishment from both wells instead of just one.

[Stinsy]

Nowty, Spread-tee

My word, that's some serious DIY civil engineering!
I will post some pics in due course of some DIY civil engineering for changing the timbers holding my roof up (without taking the roof off)!
They are flogging pumps at the local bricodepot for 100€ on Thursday, think I will buy one and see how long it takes to empty the well?
The fact there are 2 wells on the property is maybe a sign that they will take ages to re fill, on the other hand it was an agricultural property so maybe they had to provide lots of water for animals?

Peas

I was thinking, if your hell bent on doing it open source from one well into another, you could do it in such a way that every hour or so, you reverse flow the water, that way you never empty a well and that would give you heat replenishment from both wells instead of just one.

Problem with that is you’d be sloshing the same water back and forth trying to extract more heat out of it each time. It’d freeze pretty quickly…