What size Mibec pipe should I need for a 12kw ASHP?

[cbk]

I'm trying to figure out what size Mibec twin wall insulated pipe to install as part of the groundworks before I've actually chosen an ASHP or had a proper design.  First budget design suggested a 12kw ASHP would be required for UFH (approx 120m2 floor area) and DHW.  Pump will be positioned about 10m away from the house and advice elsewhere on here suggested Mibec twin insulated pipe seems are the way to go.  But should I allow for 25mm or 32mm pipes to connect from ASHP to the manifold inside the house?

 

Any advice much appreciated.

 

[Nickfromwales]

At 10m distance I would go for 32mm, but ideally you should short-list a few ASHP's and cross refence this against their installation instructions / criteria.

[cbk]

Thanks Nick, I checked Vaillant install instructions and that uses 32mm so will go with your advice.

Regards, Chris

[Stuart X-Ray]

We are just getting to your stage and used 32mm Duo pipe with a Samsung 8kW unit. Did you bury your Mibec in the ground? How deep? Did you insulate the trench? Thanks, Stuart. Roseland Cornwall.

[cbk]

Ended up with the same pipe size as you and yes it is buried in the ground and runs inside house under floor slab. I didn’t use anything special for trench so just relying on the insulation around the pipe.