ASHP grommets

[Selfbuildsarah]

Hi all

The pipes for our ASHP are being fitted through an external rendered wall of our MBC timber frame. The external rendering is starting shortly but we haven’t had our airtightness test yet. We are hoping to get ASHP pipes in through the wall and fix grommets and tape in advance of rendering (after airtightness test) so that they a render around. There are so many different grommets and tape. We think we will go for Pro Clima but not sure which. Do we need different kind for external and internal? Thanks all.

[Redbeard]

Pro Clima are good, and the Tescon tape they are based on is good for UV exposure for ...I cannot remember how long (a good period). What are the external grommets being applied to? A final render board before rendering (in which case I feel you'd need a std grommet with another layer of 'render-on' tape over) or ply/OSB on the 'outside' facing a final cavity between the OSB/ply and the render board? If the latter I think a Tescon-based grommet should be fine. Ecological Building Systems are, i think, still the importer. Why not try them?

[Nickfromwales]

5 hours ago, Selfbuildsarah said:

Hi all

The pipes for our ASHP are being fitted through an external rendered wall of our MBC timber frame. The external rendering is starting shortly but we haven’t had our airtightness test yet. We are hoping to get ASHP pipes in through the wall and fix grommets and tape in advance of rendering (after airtightness test) so that they a render around. There are so many different grommets and tape. We think we will go for Pro Clima but not sure which. Do we need different kind for external and internal? Thanks all.

It’s only the internal that needs to be airtight, the external only needs to be weathertight. 
 

Also, it’s prudent to have the pipes fall to outside, vs be laying flat (or worse, accidentally falling to inside), a good general rule of thumb for possible ingress of rainwater.

 

I would break the pipe insulation where they become exposed outside the frame, and weather-tighten there, then change to the higher spec UV resistant Armaflex insulation, setting that in to a generous ring of CT1. Wrap that exterior insulation with duct tape, where the renderer will be striking it, to keep it in good order. 
 

Once rendered, cut the insulation to leave 30mm or so remaining, complete the plumbing, and dress the UV res insulation back to that.