Extractor fan 2 fan, 2 speed unit: 1x suck 1x blow ..Standard or faulty unit/installation ?

[cumfy]

Hi,

I have moved to a property with an extractor, twin fan, two speed, wall mounted, in a small windowless bedroom which I assume has been installed to comply with building regulations.

The odd thing is that one fan blows and the other sucks. I tested with a thin plastic bag. Both speeds work.
Is this a standard set-up ? I can't find anything on their website that would suggest it is.
I would expect both fans to extract and am curious as to whether this might possibly be a production fault or a modification.

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[PrenticeBoyofDerry]

Sounds strange, make/model please.

 

[cumfy]

Ventaxia. No model markings.

 

[^woody^]

If its windowless, then one is an input fan.

But if the bedroom is windowless, I'm wondering how it complies with building regs in the first place?

 

[PrenticeBoyofDerry]

There are heat recovery fans that will let air back in, but I doubt one would have a two speed facility where one speed does one thing and the other the reverse.

 

[cumfy]

If its windowless, then one is an input fan.

But if the bedroom is windowless, I'm wondering how it complies with building regs in the first place?

I guess it is just an internal room not bedroom technically.
Is an input fan required for windowless rooms under building regs?
That would explain it, but seems like an odd stipulation; much more effective to have an extractor..... Surely ?

 

[JohnD]

i have seen it done in the "break room" in an office building, where people might be eating pies, burgers, pot noodles or egg sandwiches (it might formerly have allowed smoking).

It takes away the need (usual with an extractor fan) for replacement air to be sucked in from the rest of the building, so the air throughput rate is unusually high and the room is kept fresh.

 

[^woody^]

I guess it is just an internal room not bedroom technically.

If you've moved to it, (purchase or rented) then you need to get it clarified what the room is. If its a store room then that's OK, if its presented to you as a habitable room then maybe not - unless there are other fire precautions elsewhere.

A room needs fresh air in and out and so without a window, a fan is normally the next option. Most likely is a heat recovery unt, but there are older "acoustic fans" too. If you post a picture of the grill it can be identified, or you can just google on V/A's range of current and older models.

 

[cumfy]

It takes away the need (usual with an extractor fan) for replacement air to be sucked in from the rest of the building, so the air throughput rate is unusually high and the room is kept fresh.

But doesn't the air tend to just get recirculated, with the just expelled air getting sucked back in (on both sides) ?
The outside is just the common stairwell of a set of flats, so there is no wind.