Intake and Exhaust Ducts

[Mr Blobby]

Apologies if this has been covered elsewhere.  I did look, honest.

 

MVHR unit is going into warm loft. What ducting to the outside?  Should it be insulated?  If so what type is best?  This stuff?

 

 

... because it looks a bit too bendy, surely rigid ducting would be better.  If so then what insulation?

 

Also, the external vents all seem to be 180 diameter, the Zhender unit is like this:

 

 

... what size duct do I neeed to the outside, 200 or 180?

 

I do have a package quote from BPC but none of this stuff is clearly described.  I'll give them a ring I think....

 

[joe90]

I used 180 flexible ducting then wrapped it in rockwall insulation to stop condensation from cold air in the incoming pipe in a warm loft.

[JohnMo]

I used polystyrene duct - UBBINK AERFOAM INSULATED DUCT 

[Mr Blobby]

5 minutes ago, JohnMo said:

I used polystyrene duct - UBBINK AERFOAM INSULATED DUCT 

 

I like the look of this.  I see it in the marketing pics for Brink and Zhender but not sure if BPC sell it.

 

Would you use this again, and why?

 

[JohnMo]

I quite like it, but you can also get slightly thicker version from other manufacturers. I got it from EpicAir, they are quite good to deal with and if not not their site they seem to be able to get hold of it.

 

Easy to use and cut, not cheap but gives a nice finish. better than trying to make a bendy floppy duct straight.

 

[MikeSharp01]

Yep we will be using the UBBINK AERFOAM INSULATED DUCT via Epic, cos they are local and I can save the delivery costs, My only question though is what do people go up through the roof with - the UBINK cowels have a massive flow restriction .

[Mike]

Just had a delivery of Zehnder Comfopipe in foamed polypropylene. Not too dissimilar to the Ubbink, but with smoother bends (of which I have quite a few). They'll be mostly sitting in the ceiling insulation for additional, er, insulation.

 

Avoid the flexible duct at all costs.

[Mr Blobby]

On 05/02/2024 at 21:33, Mike said:

Just had a delivery of Zehnder Comfopipe in foamed polypropylene. Not too dissimilar to the Ubbink, but with smoother bends (of which I have quite a few). They'll be mostly sitting in the ceiling insulation for additional, er, insulation.

 

 This is what I would like to use, but, AFAICS, BPC don't sell either the Comfopipe or Ubbink, just the hard plastic duct and then the insulation to go round it. 

Which is much cheaper but looks a bit crapper.  I can see my builder rolling his eyes, again, when I tell him I want to do something different 😆

 

My next stupid question is what is the best way to terminate the foam duct at the vent in the cavity wall? Does the foam pipe go throught the cavity to the vent?  Or alternatively, run a peice of 180mm thin plastic duct through the cavity wall and join the foam duct to that?

Edited February 12 by Mr Blobby

[JohnMo]

23 minutes ago, Mr Blobby said:

best way to terminate the foam duct at the vent in the cavity wall?

Have two units, one through timber stud wall, the foam was taken through the wall, the other unit goes through ICF and that had a cast in place hard plastic duct, with a stub on the inside flush on the outside.

[Mr Blobby]

On 12/02/2024 at 18:08, JohnMo said:

cast in place hard plastic duct, with a stub on the inside flush on the outside.

 

This seems like a good idea.  What pipe and vent did you use through the wall?

 

My concern is that the 200mm comfopipe has a 280 outside diameter.  Thats seems like a very big hole through a block wall.

I'm looking at a 200mm blauberg plastic pipe to a 200mm blauberg vent as an alternative like this:

 

 

The 200mm comfopipe should slide over the blauperg pipe ok I think and then it looks like the external cowl from the same manufactruer will slide into the rigid pipe ok.

As well as looking easier to install through a smaller hole in the wall the bull nose cowls are a third of the price of the zhender grills.

 

 

 

I suppose my unknowns are:

 

1.  Would it be structurally ok to have a 280 mm hole in a block wall for the Zhender 280 insulated pipe to go to the outside?

(I can get a firm to core drill it thanks to @Conor's advice elsewhere, I hust dont want the wall to collapse 😬)

 

2. Do I need insulated pipe through the cavity?  The cavity is insulated anyway. 

 

 

 

[JohnMo]

1 hour ago, Mr Blobby said:

What pipe and vent did you use through the wall?

I just used white solid plastic pipe

[Nickfromwales]

On 12/02/2024 at 17:42, Mr Blobby said:

 

 This is what I would like to use, but, AFAICS, BPC don't sell either the Comfopipe or Ubbink, just the hard plastic duct and then the insulation to go round it. 

Which is much cheaper but looks a bit crapper.  I can see my builder rolling his eyes, again, when I tell him I want to do something different 😆

 

My next stupid question is what is the best way to terminate the foam duct at the vent in the cavity wall? Does the foam pipe go throught the cavity to the vent?  Or alternatively, run a peice of 180mm thin plastic duct through the cavity wall and join the foam duct to that?

You have a cavity wall / masonry build yes? If so, the foam will be subject to the conditions within the cavity, dripping condensation off a snot or tie etc, so I would use the rigid plastic for longevity. I'd use 200mm plastic through internal leaf, with the foam 180 inside that, and then lose the sleeve as you get to the inside face of the external leaf, drop the hole dia to 180mm and then punch through with the foam to the outside facade.