Air Brick

[Diggory]

I’ve got an original air brick in a shower room.
The external wall has a cavity but narrow by modern standards; maybe 50mm.
It’s an old style vent; terracotta square grid on outside wall and plaster louvre on inside wall.
I’m fitting an in-line loft fan to the shower room and wondering if I should close up the vent.
I’m thinking that maybe I should draw my replacement air from the (warmer) house and not cold air directly through the vent.
I’m wondering if the colder air will increase my likelihood of condensation.

Advice greatly appreciated.

Best D

 

[Deluks]

Have you got a small gap under the bathroom door, that will usually do it.
If the vent is too close to the extractor you will create a loop, creating airflow between the two which might leave other areas of the bathroom damp.

Short answer, close it off.

 

[Ivor Windybottom]

Yep, ensure there's a 10mm gap under the door. It sounds like a lot but it looks totally normal. The extractor should be as far as possible from the door, as high as possible. Then you get a current of air across the whole room, clearing the lot.

An inlet vent can reduce the effectiveness of the fan, by providing a short-circuit route for the air that leaves the air in the rest of the room uncirculated. It's possible that it's only there because either fans hadn't been invented yet, or because there was once a gas water heater fitted in there.

 

[Diggory]

Thank you @Deluks & @Ivor Windybottom; much appreciated.
I’ll close it off as I’ve got a gap under the door - albeit not quite 10mm.
Having just replaced carpet with LVT, the flow under the door is smooth / unrestricted.
I can always plane a bit more off the door or even fit a vent in panel of the door.
By coincidence- I’m planning on adding a vent to the adjacent airing cupboard door so wouldn’t look too odd.

Best D

 

[Ivor Windybottom]

Just ensure there's a 10mm+ gap, I promise it won't be noticeable. A vent would look horrible and end up full of towel and bog roll fluff.

If you have a decent extractor you'll be able to feel the air rushing in under the door with your hand from inside it.

 

[Diggory]

Fair point - I’ll get the plane out.

Best D