ASHP pipework in floor below the insulation - any guidance?

[AAA]

Hi everyone,

 

Newbie poster here. Newbie ASHP-er as well! I am really hoping someone here can help....

 

Pipework for our ASHP (Samsung Gen6 8kW) is being installed at the moment, and the ASHP will be in a new build extension to our house, located on the rear external wall. The pipework runs approx 5m internally in a straight line to a very small plant room (cupboard). So everything for the HP is in the newbuild part of the house. I have a question about where the installer has put the pipes to and from the ASHP relative to the floor construction.

 

The floor will be made up of 100mm concrete slab / DPM / 150mm PIR insulation / another DPM / UFH pipework / screed.

 

The heating engineers have installed the inflow and outflow pipes from the ASHP on top of the concrete (ie under the insulation). The insulation they've put around the pipes looks like just the standard grey lagging you put around pipes inside a house and they're not laid on any extra insulation or anything. This, to me, is a crying shame, because of the heat losses that just wouldn't happen if the pipes were chased into the PIR. But because they've already installed the pipes, and they want to get on with the PIR and UFH I am certain they'll strongly resist my efforts to get them to change it and tell me a load of old rubbish as to why it's not possible.

 

They've done loads of ASHP installations (and are very confident in their own abilities...) so something 'official' would really help me. Can anyone point me to any guidance that covers where pipes should be located / minimum insulation standards?  I looked at the MCS information and couldn't see anything specific, will take a look at Samsung installation guide too.

 

I will be very grateful indeed if anyone can help. 

[JohnMo]

I would just biased the pipes to the the top of the insulation. Or even on top of it, depending on screed thickness. Certainly wouldn't be at the bottom, no matter what the contract says. 

[AAA]

Thanks JohnMo. Sorry for the stupid question - what does biased mean?

[Kelvin]

Our flow/return pipes are the duo insulated pipe type which is run under the concrete slab (so basically in the ground) The insulation of these duo pipes isn’t much better than the stuff your installers have used other than it’s continuous. It’s not an uncommon way to do it.
 

In your case chasing it into the insulation shouldn’t be too hard to redo. If they refuse to change it at least make sure the insulation lagging of the pipes is done well with no gaps and the joins are taped. 

[AAA]

Thanks Kelvin!

 

The lagging they've put on our pipes looks like it's this stuff - only about 13mm thick

https://www.screwfix.com/p/pipe-insulation-28mm-x-13mm-x-1m-35-pack/43273?tc=OT9&ds_rl=1241687&ds_rl=1245250&ds_rl=1249404&gad_source=1&ds_rl=1245250&ds_rl=1247848&ds_rl=1248151&gclid=EAIaIQobChMIg7uW-tq-hgMVp4FQBh1DxADFEAQYByABEgJiY_D_BwE&gclsrc=aw.ds 

 

 

Would the standard be to use duo insulated pipe instead? What's a reasonable minimum thickness of insulation?

[Kelvin]

It’s not necessarily a standard to use the duo insulated pipes it’s just a common and easy way to do it if going underground. It’s also used for community heating installations. Some folk on here have made their own by using pex pipework, 25mm insulation, then inserted into ducting (110mm) 
 

It would be better if it was 25mm closed cell pipe insulation like this stuff. This is same stuff they ought to be using to insulate the external pipes where it connects to the ASHP. 

 

https://pipelaggingonline.com/shop/armaflex-class-o/

Edited June 3 by Kelvin

[JohnMo]

1 hour ago, Kelvin said:

common and easy way to do it if going underground.

If you are not going underground it's not a cost effective solution. I would just tell the installer you want to put 100mm of your 150mm insulation below the pipes.  If you want everything flush prior to screed you may need to trim the 100mm down a little. Leave there 13mm insulation in place.

[Conor]

It should be relatively easy to unclip the pipes, put 50mm insulation down, clip them down again, then lay the remaining insulation. It's minutes of work. They just want to get the job done and be gone.

[Dillsue]

If you've got 150mm of high performance PIR insulating the room from the ground, why would anyone think half inch or so of cheapo pipe insulation would be good enough to insulate the HP flow and return from the ground.

 

You wouldn't accept water slowly dripping from a pipe so there's no reason to accept heat slowly "dripping" from the pipes.

[AAA]

Thank you everyone! It really helped to have your knowledge behind me.  Took a bit of negotiation with the contractor, but pipes are now inside 25mm continuous closed cell insulation and on top of 50mm PIR as well, with the rest of the 150mm floor insulation built up snugly around them. Not quite as good as them just being inside the thermal envelope of the house but considering where we started I'm really pleased with the end result.

A 

[JohnMo]

That should work