Heat Recovery in Attic

hexosan

I'm having my MVHR installed at the moment and a question has arisen, should there be an inlet or extract point in the attic.

Attic is inside the thermal envelope of the house. It won't be habitable for the time being but may be used down the line.

893bet

hexosan wrote: »

I'm having my MVHR installed at the moment and a question has arisen, should there be an inlet or extract point in the attic.

Attic is inside the thermal envelope of the house. It won't be habitable for the time being but may be used down the line.

If it is inside the airtight layer then I would assume it needs ventilation. You don't want your attic timbers getting damp. That said there would be no real source of dampness up there.

Conclusion. I have no idea.

hexosan

893bet wrote: »

Conclusion. I have no idea.

Same as me so.

BryanF

Is the layout designed for future use?

If you were to extract could you recycle the heat that rises?

Can a suitably central located service chase be provided to allow for future extension to the system?

hexosan

BryanF wrote: »

Is the layout designed for future use?

If you were to extract could you recycle the heat that rises?

Can a suitably central located service chase be provided to allow for future extension to the system?

The attic is left open plan for the time being and I can erect stud walls to section it off at a later date.
MVHR pipes are all at the back of the support walls in the attic so easy to tap into them later.
I wondered about the warm air that would rise into the attic been recirculated back down into the house. Supplier reckons because it's an attic space with no heat source it shouldn't have the MVHR installed but will put it in if I want it.

SemperFidelis

I'd put a point in and close off the valve then its just a case of opening the valve and re-balancing the system if required in future.

hexosan

SemperFidelis wrote: »

I'd put a point in and close off the valve then its just a case of opening the valve and re-balancing the system if required in future.

That's what I'm going to go with but now to decide if it should be an inlet or extract.

Strolling Bones

hexosan wrote: »

Attic is inside the thermal envelope of the house. It won't be habitable for the time being but may be used down the line.

for the reasons highlighted - yes

BryanF

Could the system be balanced with an extract only in the attic? What kind of hatch at ceiling level is being used?

exaisle

hexosan wrote: »

That's what I'm going to go with but now to decide if it should be an inlet or extract.

One of each I'd assume so the system would remain balanced...

hexosan

BryanF wrote: »

Could the system be balanced with an extract only in the attic? What kind of hatch at ceiling level is being used?

It's not a hatch I've a full stairs into the attic.

Outkast_IRE

Well it sounds like it should be an inlet so, as arent the extracts generally from bathroom/ kitchen / utility areas.

I assume it will be a bedroom or study etc going up there in the future so might as well leave an inlet there, or one of each if you think an ensuite or similar may go up there in the future.

rampantbunny

I'm using my attic space, two rooms, and the system designer has an air supply to each room.

Thought about questioning whether one room should have an extract, because that room would generate heat if anything due to it housing media equipment. In the end I just put my trust in the design.

Question..you mentioned you could split the space later using stud walls. Where will your duct run be in that case (regardless of it being extract or supply). Are you going to run multiple ducts for each potential part of the broken up space.

hexosan

Attic will be split into three rooms (due to shape) . I know where the walls of each are going give or take a meter or so.