ASHP flow and return routing

[HughF]

I’m putting on a single storey rear extension and need to bring the 28mm flow and return for the ashp through the floor of the new extension from the garden, and then up the now inside wall of the house before punching through the cavity wall at first floor level to run towards the cylinder cupboard in the middle of the house.

 

I can’t box in at skirting height as I’d need to cross a doorway, so it needs to come across the slab, which will have ufh in it.

Should I make up a trench with shuttering and pour around that, and then board over it (my neighbours did this when they relocated their boiler to their new rear extension)? I could follow the perimeter of the slab so to avoid crossing the ufh.

 

Or should I do something fancy with coming through the type1 layer that’s at the bottom of my floor design? 
 

I am already planning to come across the garden with some insulated twin ducting, I suppose I could carry that through the founds and up out the slab?

Edited September 15, 2022 by HughF

[TonyT]

I’ve installed plenty of AC units with buried 100mm ducting to allow the insulated  refrigeration pipes to be installed underground to avoid trouble spots,

 

just

make sure that they protrude above the finished floor level so that they can be sealed appropriately.

 

what’s wrong with following the outside of the extension, popping into the house and up a pipe box or use the proprietary ducting and run external to the first floor space?

[HughF]

32 minutes ago, TonyT said:

I’ve installed plenty of AC units with buried 100mm ducting to allow the insulated  refrigeration pipes to be installed underground to avoid trouble spots,

 

just

make sure that they protrude above the finished floor level so that they can be sealed appropriately.

 

what’s wrong with following the outside of the extension, popping into the house and up a pipe box or use the proprietary ducting and run external to the first floor space?

It’s a full width rear extension, and I detest externally exposed pipe work even when boxed in. I also can’t bring it up the side of the house as I the joists run the wrong way. I’ll do a drawing to explain it better.

[HughF]

A couple of sketches. The ashp will either go on the wall, or up the garden. I’d prefer the up the garden option, as would my wife. It would be 15m of underground twin ducting though.

[TonyT]

Run it internally then in a stud wall /behind a stud wall with no joins in the copper pipework 

[TonyT]

Or plastic pipework

[HughF]

8 hours ago, TonyT said:

Run it internally then in a stud wall /behind a stud wall with no joins in the copper pipework 

I don’t have any walls to run it in, the extension is open plan…

 

It has to go in the floor, I just need advice on which part of the floor to put it in. I’m leaning towards either in the insulation layer (along with the ducts for the ventilation of the existing suspended floor void) or in the type1 layer. Either way I’m going to need to come through or below the footing.

[jfb]

27 minutes ago, HughF said:

I’m leaning towards either in the insulation layer

Well it is going to need insulating wherever it goes so why not here

[HughF]

3 hours ago, jfb said:

Well it is going to need insulating wherever it goes so why not here

Fair point…. I guess it depends on whether the heat pump goes up the garden or against the wall. Against the wall then the flow and return can punch through the 2 courses of block work below dpc and end up in the insulation layer. 
 

If up the garden then I’ll buy £1k worth of twin insulated 32mm and bring it right into the house under the floor void. Quicker, easier, less figuring out to do.