Heating pipes through external wall- best practice

[cwr]

Evening all,

 

One of the next jobs on my list is to get a pair of 28mm pipes out through an external cavity wall to the boiler that's mounted in an outside steel housing, which sits about 2 inches from the rendered external wall.

 

I am wondering on how best no do this, I'm sure others on here will have a good solution.

 

My current line of thought is to run pipes in a pair of plastic ducts, say 68mm (ie bit of downpipe), with 19mm pipe insulation. Then somehow seal the inside end to the plaster ( for airtightness).

 

Or perhaps run both pipes in a single larger duct?

 

 

[joe90]

To get the flexi pipes to my ASHP I core drilled 2 x 80mm holes and used pipe insulation with 75mm OD from the unit right through to the inside and sealed to the plaster skin with flexible silicone. 

[Nickfromwales]

1 hour ago, joe90 said:

To get the flexi pipes to my ASHP I core drilled 2 x 80mm holes and used pipe insulation with 75mm OD from the unit right through to the inside and sealed to the plaster skin with flexible silicone. 

+1, but I would have sleeved ( ducted ) the pipes as it’s a cavity. 

[Nickfromwales]

If ducted, and in a cavity wall, they need to run downhill to the external leaf also.