I put GSHP in our Barn Conversion and dug the 2 x trenches for the slinkies mysefl (with a 10T digger) to keep the cost down. RHi was a big incentive though. No mains gas here.
Not sure what to do for the next building conversion, if we can get near passive then a GSHP is probably overkill and the money better spent on PV instead, with immersion for DHW.

Posted By: Dominic CooneyStill contemplating GSHP for the main farmhouse to ditch the oil,

But why GSHP rather than ASHP?

In other countries GSHP performs better than ASHP 4.5 compared to 3.5 CoP for ashp here GSHP seems not to perform very well but it should. I suspect scrimping on depth of heat field or boreholes

As RobL says
No outdoor fan unit. Plus we already have 'boiler room' where the heat pump would go and plenty of room for unvented cylinder. Although I guess it would be feasible to connect to an outdoor ASHP unit, the boiler room isn't on an outside wall.

I already have PP as I put in for the barn and the house at the same time (the slinkies are in the field, not in the curtilage, so technically needs PP)

As Tony says, I have been very impressed with the CoP of the Kensa GSHP installed in the barn. We did make the trenches a few metres longer than specified and looped the extra pipe to make about 7 more loops in each of the two trenches. there's also about 40m from the barn to the manifold in the field which will gain a bit of heat from the ground along the way.

As with all things, insulating the house better makes the whole thing cheaper and easier when it come to the heat pump, Air or Ground source.

Posted By: Dominic CooneyI am making sure to put a suitable elec cable in from Consumer Unit to Plant Room (currently boiler room) and also larger mains water pipe from stopcock to plant room. (while the floor is up in the bathroom upstairs)

It's an interesting question what extra infrastructure to build into a house against possible future developments. I put several extra cables from the CU to the wet rooms and living room to serve possible heaters (I've subsequently fitted heaters to two of the five) and extra cables from the wet rooms to the plant room for possible humidity sensors for the MVHR (none fitted so far). I also fitted a spare duct between the house and garage so as to be able to run comms cables, but the end in the house is behind a plaster wall so in reality I used first a wifi connection and latterly a powerline system instead :( When I contemplate fitting a split ASHP I wish I'd run some more ducts for the refrigerant pipes and the power, but hey-ho. Hindsight is a wonderful thing.

Lineweight, I'm in a similar position to yourself. I have currently got a GSHP (Worcester Bosch) and it's been very reliable. I was fortunate and got the RHI for this installation. Building again I don't have that luxury so I'm also considering GSHP, ASHP, oil as I'm off gas network. My concern with the ASHP is that I live close to the coast. I'm sure in 5-10 years I'd have a rusty ASHP looking worse for wear with noisy bearing spinning away. GSHP's are expensive though and I bored last time. I'm also considering 10kw PV for power and DHW in summer and using oil for winter months. I don't like fossil fuels but my GSHP does cost around £500 a month with some EV charging thrown in but not much. Oil would be more economical imo but I like renewables if the grid is green.

Posted By: tonyPresumably, the better insulated your home is DHW becomes a bigger proportion of your energy use

This is the dilemma I had as my previous abode the space heating was greatly in excess of the DHW one did not need to bother. When doing our current abode we had difficulty working out what we needed so put in solar thermal which negates any use of "fuel" from March to October it then takes the "chill out of the water in the thermal store in the winter which feeds the ufh.

Posted By: gustyturbineI don't like fossil fuels but my GSHP does cost around £500 a month with some EV charging thrown in but not much. Oil would be more economical imo but I like renewables if the grid is green.

If you do a very good job of the fabric 1st approach you do not need a sophisticated source of heating. We spend less than £300 pa on bottled gas which we started off with to see if we could mange without a propane bulk tank, As we do not need much the £100 "maintenance fee" would make bulk gas dearer than our bottled. We have 6kw solar pv + battery and we are more than cost neutral on electricity. The export last year covered the cost of the gas. House by the way is 340 sq M but lots of solar gain and thermal mass which makes a big difference. A wood burning stove in the lounge augments the heating.

Posted By: lineweightis GS something that is only worth even thinking about... where a garden area is available, and ones where the budget is fairly generous?

A garden isn't necessary - I've seen one in a London house with vertical boreholes through the floor, but that wouldn't have been cheap.

Posted By: Mike1

Posted By: lineweightis GS something that is only worth even thinking about... where a garden area is available, and ones where the budget is fairly generous?

A garden isn't necessary - I've seen one in a London house with vertical boreholes through the floor, but that wouldn't have been cheap.

Not just expensive but very disruptive I imagine.

Re Ground Source piles in London - piled foundations are often necessary in any case.

This build claims to combine the two -
"with a range of features including ‘energy piles’ |(heating coils inserted within ten of the foundation piles) utilising a solar-assisted ground-source heat pump to create a thermal store beneath the building; PVTs (solar thermal panels);"

They're a neighbour. The house has changed hands a couple of times and I know there were some issues with the heating early on (the second owners replaced the GSHP with a larger unit I think) but, without knowing any of the tech details it *seems* like a good solution - combine structural piles with GS piles. IIRC they were combined Solar Thermal/PV panels with the idea being the thermal cools the PV increasing the efficiency and the excess hot water is pumped into the piles to create a ground thermal store.

I seem to remember reading (on here?) that that type of panel was not so great but would be interesting to have a proper tech analysis of the system.

https://www.archdaily.com/300175/slip-house-carl-turner-architects/50b7da21b3fc4b239a00011e-slip-house-carl-turner-architects-section?next_project=no

What I don't understand is this comment from the architects own site -
https://turner.works/thoughts/post/slip-house-in-details/
"The house is preforming brilliantly–once the heating is turned off it takes a good 12 hours for the temperature to drop by a degree or two. However you have to get used to not opening the doors unless it’s 22 degrees outside"

All the floors (and ceilings) are precast concrete and it's described as having a high level of insulation - it should have huge thermal mass. Our own house only has a concrete ground floor (and Fermacell internal walls which must give a significant bump to mass over plasterboard) - you can open doors wide in really cold weather and the retained heat of the structure very quickly warms the internal air. So that seems odd.

Maybe it takes the excess heat from the London Underground transport system which I seem to recall something on here about it increasing year on year in the surrounding soil.

Posted By: Simon StillRe Ground Source piles in London - piled foundations are often necessary in any case.

This build claims to combine the two -
"with a range of features including ‘energy piles’ |(heating coils inserted within ten of the foundation piles) utilising a solar-assisted ground-source heat pump to create a thermal store beneath the building; PVTs (solar thermal panels);"

They're a neighbour. The house has changed hands a couple of times and I know there were some issues with the heating early on (the second owners replaced the GSHP with a larger unit I think) but, without knowing any of the tech details it *seems* like a good solution - combine structural piles with GS piles. IIRC they were combined Solar Thermal/PV panels with the idea being the thermal cools the PV increasing the efficiency and the excess hot water is pumped into the piles to create a ground thermal store.

I seem to remember reading (on here?) that that type of panel was not so great but would be interesting to have a proper tech analysis of the system.

https://www.archdaily.com/300175/slip-house-carl-turner-architects/50b7da21b3fc4b239a00011e-slip-house-carl-turner-architects-section?next_project=no" rel="nofollow" >https://www.archdaily.com/300175/slip-house-carl-turner-architects/50b7da21b3fc4b239a00011e-slip-house-carl-turner-architects-section?next_project=no

What I don't understand is this comment from the architects own site -
https://turner.works/thoughts/post/slip-house-in-details/" rel="nofollow" >https://turner.works/thoughts/post/slip-house-in-details/
"The house is preforming brilliantly–once the heating is turned off it takes a good 12 hours for the temperature to drop by a degree or two. However you have to get used to not opening the doors unless it’s 22 degrees outside"

All the floors (and ceilings) are precast concrete and it's described as having a high level of insulation - it should have huge thermal mass. Our own house only has a concrete ground floor (and Fermacell internal walls which must give a significant bump to mass over plasterboard) - you can open doors wide in really cold weather and the retained heat of the structure very quickly warms the internal air. So that seems odd.

It may be unfair to judge a 2006 project in 2023... but spot the cold bridges

https://linituk.com ? Yeah, pics look like it.

Thanks, interesting link! Heat pumps of the 'air-con' style have been mounted on urban roofs and upstairs walls for many decades. This one is mounted inside the loft with ducts to suck in air, which has been done before with EAHPs and DHW tank heatpumps.

Will be interesting if it takes off for CH units, internal noise and weight are the obvious issues. But its good to see new things being tried out, especially by a gas boiler company that was pushing for gas boilers to be retained in the hope that hydrogen might arrive for them!

<blockquote><cite>Posted By: WillInAberdeen</cite>Thanks, interesting link! Heat pumps of the 'air-con' style have been mounted on urban roofs and upstairs walls for many decades. This one is mounted inside the loft with ducts to suck in air, which has been done before with EAHPs and DHW tank heatpumps.

Will be interesting if it takes off for CH units, internal noise and weight are the obvious issues. </blockquote>

It sounds good in principle but there are a few issues that it will be interesting to see the solutions for -
1) you've now put the supposedly noisy, supposedly vibration prone object within the house structure. I've heard of issues even with loft mounted MVHR units transmitting vibration through the house structure (which magnifies noise).

You're not just going to be dropping these on top of a board on top of ceiling joists

2) ASHP needs to move a lot of air - it's going to need a really big vent hole. And somehow you're going to need to silence that (otherwise any noise from the unit is just going to end up transmitted down the duct and still be audible to neighbours.

But encouraging to see alternative solutions. A lot more likely to work efficeintly than the AirCon units I saw in a French restaurant where they'd stuck them in a small space under a roof.