extractor fan is barely drawing. Can't access it.

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An extractor fan in a windowless bathroom is barely drawing, I can feel only the slightest pull and a smoke test confirms. Tenants report that steam is very slow to clear and, indeed, after years of no problem the black mould is advancing.

The fan sounds normal - not too loud or quiet. I can't seem to access it, the loft doesn't go over the bathroom, so it may be sealed into the ceiling (is this possible?). The house was completely renovated into a rental style about ten years ago, I'm trying to hear from the vendor (I bought it 2.5y ago) about that point and if he can advise.

It vents out through the roof itself, under a special tile - there's a grill and the pipe clearly pops out there.

Can anyone advise on this situation? Is there much I can try to do to get it moving, could it be clogged up and need clearing out? Stick a Henry hose up the hole in the ceiling?

If it's whirring nicely but not drawing, could it still be a fault with the fan itself?

Many thanks,
 
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do you have a 12mm gap under the bathroom door to allow warm air to be drawn from the house and aid the airflow ??
try cracking the door open a few mm and see what happens ??
 
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do you have a 12mm gap under the bathroom door to allow warm air to be drawn from the house and aid the airflow ??
try cracking the door open a few mm and see what happens ??

This is all with the door wide open. It's quite a large house, as well, though I don't suppose any windows were open at the time of my test. Would that make a difference.

In any case, for years (also before my ownership) it sufficiently kept the mould at bay so I wonder if something has changed, you see, rather than it having been inadequate from the start.
 

JohnD

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do please show us photos, of the fan and of the duct and outlet you mention.

There might be fluff (or birdsnest) clogging, but there are some excellent extractors on the market now that are both quieter and more powerful than old models. Especially the ducted ones.

100mm duct is typical but there are larger sizes, you need to know what yours is. If you can see make or model names or numbers that will help.
 
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This is all with the door wide open. It's quite a large house, as well, though I don't suppose any windows were open at the time of my test. Would that make a difference.

In any case, for years (also before my ownership) it sufficiently kept the mould at bay so I wonder if something has changed, you see, rather than it having been inadequate from the start.
you are better with the door shut or cracked open a few mm
whilst i would expect a smoke bomb or burning taper to draw smoke easily if you are inches away from the ducting with an open door what you want is a pressure imballance to cause flow that wont happen easily with a gentle fan and an open door
 
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do please show us photos, of the fan and of the duct and outlet you mention.

There might be fluff (or birdsnest) clogging, but there are some excellent extractors on the market now that are both quieter and more powerful than old models. Especially the ducted ones.

100mm duct is typical but there are larger sizes, you need to know what yours is. If you can see make or model names or numbers that will help.

Attached is a picture of the vent and duct, it's 100mm. The fan mechanism itself I can't see or access, I'm trying to find out if that portion of the loft is accessible perhaps from a neighbour's house or something. I did a toilet-paper test and it will hold a sheet tight to the grill. It is clearly a bit dirty so I'll vacuum out the duct but I don't yet know how far it goes. I can estimate the full distance from ceiling to outside must be at least 2-3m

Screenshot_64.png


I couldn't get any useful picture of the roof outlet, it's too small and I only have a phone camera. I'll get my ladders up there but I can see it's not blocked on the outside, at least.

you are better with the door shut or cracked open a few mm
whilst i would expect a smoke bomb or burning taper to draw smoke easily if you are inches away from the ducting with an open door what you want is a pressure imballance to cause flow that wont happen easily with a gentle fan and an open door

Ah, interesting, ok - that does make sense.

Yes, now there are tenants.

It's like they come infected with black mould, isn't it!
 

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