Insulating the unit in a cold loft?

[Jim K]

I'm soon about to retrofit a Vent-Axia Sentinel Kinetic BH to my bungalow, so it'll be going into a cold loft.

 

I have an opportunity to build an osb box to hold and contain the unit, and there's an option to make it a bit larger I can also add insulation. I'm getting conflicting advice from forums, Vent-Axia technical and the manual that comes with it as to whether I should, and if it's worth it.

 

I want to get as close to the 90% claimed heat recovery as possible, so it seems there are 3 options:

 

1. No insulation: AKA "it doesn't need it, just do the ducts", put it on a shelf in the loft and forget about it.

2. Build a box & loosely insulate: cut neat holes for the ducts and stuff loft insulation around the unit, but leave small gaps for it all to breathe in case the unit "sweats".

3. Build a box and SEAL it: Celotex, tape, make it tight with no air gaps for maximum heat retention - but also no airflow for any dampness that might creep out.

 

If it was your house what would you do? Is condensation (other than the condensate pipe) something to consider?

Edited August 8, 2023 by Jim K

[jayc89]

I plan sandwich some sheets of OSB between 50mm PIR and build a "room" out of it. Will use it for the MVHR unit as well as a few other bits and bobs. 

[Jim K]

I've gone with somewhere between option 1 (just put it on shelf/wall) and option 2 (loosely insulated box)... Once it's in place in the loft and proven to work, i'll put some extra loft or duct insulation over the top of it all to protect the unit from excess heat from the roof in summer, and keep it a bit warmer in winter.

 

Anything more complex and it risks being hard to access the unit if ever needed for anything more than a filter change.

Edited August 31, 2023 by Jim K

[Big Jimbo]

Sounds like a plan.