Looking at a potential house that needs a complete overhaul. I’d like to install ground source heating but the garden slopes, at a very rough guess, 2m height over 40m long (garden is approx 20m wide)

How much complexity and cost would that add to digging the trenches for the source pipes?

Anyone any experience with things like this?

Before you even get that far your garden is 40m x 20m? Is that enough room to get enough pipe in? Is your house suitable for low temperature emitters? Lots of questions before you even look at outside

You need to assess the heat demand for your heating in Kw, then you can consult data which can tell you how much heat you can expect per meter run. If surface area likely to be insufficient then bore holes can be an option.

As a rough rule of thumb – you need 50m2 per kW of heat load.

If you are gutting it, and reinsulating to at least current minimum building regs, then you can (again, rough rule of thumb) assume 50W/m2 – so a 150m2 build, will have a peak heat load of 7.5kw, requiring 375m2 of ground loops.

Remember the above is a very rough guide – ground thermal conductivity will vary by the ground type – sand/gravel needs more area, wet soggy loam may need less.

Best to get an expert to quote/design.

Btw, the slope is irrelevant regarding the pipes/pump – its a closed loop so what you pump up the hill, falls down the other side.

Also, make sure the heat emitters – rads or underfloor are sized to suit the flow temp of the heat pump. Rads typically trebled in size, underfloor centres at 150mm.

cheers guys.

Proposed floor space is, by chance, 149.87m2 according to Autocad, so Ssmudger’s numbers fit in perfectly. So need 375m2 of land, and even if I’ve over-estimated the dims, I’m certain I’ve got more than that. We’ll potentially be digging the garden up anyway to remove some massive trees (and provide firewood for stoves), which is why I had the idea.

I know about the radiator issue. I’d fit underfloor heating throughout, replacing the floorboards etc in the process.

Obviously, I’ll get the experts in when it comes to it, my main concern was the slope, which Smudger has again explained.

Your talking about £30,000 or so to do the job properly.