Insulating ducting in the loft

[ADringer]

Hi all,

 

Just had my MVHR installed in the unheated loft and was planning on running the ducting underneath the loft insulation. This isn't actually feasible as I underestimated how much ducting there was and how much space there is for the loft insulation!

 

So I'm looking at alternatives, and I'm thinking the easiest thing to do would be to get something like this: https://www.bpcventilation.com/insulated-flex-duct. Would this be ok? Manufacturer instructions says I need 25mm wool insulation so this should hopefully be ok.

 

The only thing I wasn't sure of was my ducting is 90mm, whereas that lagging is 100mm - does having this extra 10mm gap make any difference in performance?

 

Thanks

[Dave Jones]

could always wrap the ducting in this insulated ducting, would be overkill but more is better right.

 

https://www.screwfix.com/p/manrose-aluminium-insulated-flexible-ducting-hose-silver-10m-x-102mm/90765

 

 

[Iceverge]

You could use a blown insulation like cellulose to bury it completely. 

[ADringer]

1 hour ago, Dave Jones said:

could always wrap the ducting in this insulated ducting, would be overkill but more is better right.

 

https://www.screwfix.com/p/manrose-aluminium-insulated-flexible-ducting-hose-silver-10m-x-102mm/90765

 

 

Yeah that's the sort of product I was looking at (linked in my post), but Screwfix is almost double the price! Would it be an issue having a 102mm wrap around a 90mm pipe? Would the air pocket make any difference?

[Andehh]

If sealed off fully, the air pocket would prob help!