Flow return pipes under passive raft or through walls

[Meabh]

We are doing groundwork for a passive raft and the walls will be ICF. ASHP will be located outside the pantry window area) which is  about 5/6m from the plant room. Opinions on how to install the flow/return pipe please?

Option 1 - pre-insulated twin pipe under the raft insulation but with a 90 degree fixing to get the pipe up to the plant room or

Option 2 - through the walls.

Many thanks

[Nick Laslett]

This thread here might be useful. 
 

 

The forum creates some challenges because it is difficult to know sometimes where a topic might fit. Discussion about insulated twin pipe, not many opinions on this at the time. 
 

This discussion also covers pipe sizing. 
 

 

Edited May 18, 2023 by Nick Laslett

[Conor]

We cored a 100mm hole in our wall and ran the pipes plus power / data cable through it in individual ducts, foamed it up after. Then they all go through the outer insulation layer of the wall, finally rendered over. Only bit of insualtion actually needed we're for the flexy hoses coming out from the wall to the unit.

[JohnMo]

Ours ended up being done a year after the house was complete. Converted to 28mm copper before coming up the wall. Then core drilled 2x 50mm holes, placed copper tube central in the holes (slight upwards to allow self bleeding) and used expanding airtight foam to keep in place. And then sealed the ends at the wall with sealant.  Then used external 19mm insulation.

[HughF]

The 90 degree elbows for the insulated twin stuff are not cheap... Something to bear in mind.