Bathroom Extractor Fan

[trevalex]

Hi
I just moved into a flat I purchased last month. One of the things that needed fixing was the bathroom extractor fan as it was very noisy.

So I set about tracking down the exact same model fan.
That was easy bit.
When I removed it I was surprised what I saw.. See images below.
1. The fan had been chopped at the back (removing the back draft flap) in order to fit it to the ceiling.
2. The hole in the ceiling looked all wrong..
I don't know much about ventilation ducts in flats.. But I would expect the fan would somehow attach to the duct in some sort of air tight manner..
This looks like just by luck (or bad building) it sits over the duct.

Anyway I thought like for like for the time being…so I put my new fan motor inside the housing of the old fan(the one that was butchered).. in order that i could at least have a fan that if anything didn't make much noise when I used it.

In my mind though thinking this surely doesn't work if their is no actually duct attached to the fan… to me it looks like just an empty space in the ceiling.
(not i can see on the roof of the flats small vents.. which I assume is where these ducts lead to).

What I am looking for is some sort of assurance that I am using the right type of fan (a centrifugal fan in this case).
And is the condensation collection normal.. ?
(Should I maybe add a drain hole?).

Thanks in advance.
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[wingcoax]

You appear to have a wall mounted fan that has been adapted to fit the ceiling. A ceiling fan does not normally have a backdraft shutter as gravity prevents then operating properly.

 

[trevalex]

Are you sure?

Description says they can be ceiling mounted.
http://www.discount-electrical.co.u...ractor-fan-with-humidstat-100mm---4-inch-240v

and

http://www.manrose.co.uk/specifications/centrifugalfanrange.pdf

I did check all this before buying the like for like.

Any other ideas?

 

[trevalex]

I have made some changed to the run time of the fan to see if this helps move the steam into the vent more..Still was surprised to see so much water collect in the cover.

 

[securespark]

It is usual with ceiling mounted fans fitted in a certain manner to fit a condensation trap into the pipe or ductwork, otherwise there is a risk the moist air will rise into the cold ducting, and condensation will drip back into the fan.

http://www.wickes.co.uk/110mm-conde...match||plid|&gclid=CMScyKuxtrYCFQ7KtAodRW4Ajg

See these instructions from Greenwood for diagrams:

http://www.greenbrook.co.uk/product-pdfs/C100_Ins.pdf

 

[trevalex]

Thanks but if you see my pictures you will see that all I have is a hole in the ceiling with a circular hole in what I presume is ducting..
As this is a flat (and hence leasehold) all I can see is what I can see once it goes into that space I have no idea what is fitted in he rest of the ducting or if a condensation trap is fitted.

I would expect their to be some sort of join between the back of the fan and the ducting.. but there isn't..
Nor is there space to fit any.. ?

 

[mattylad]

a hole in the ceiling with a circular hole in what I presume is ducting..

Best to check so that you know rather than assume.

 

[ban-all-sheds]

Thanks but if you see my pictures you will see that all I have is a hole in the ceiling with a circular hole in what I presume is ducting..

You've also got a round disc of something which appears to be plugging what might be ducting. Does it come out?

 

[stem]

To me, it looks like the duct would likely have been installed at the time of building construction and a hole should have been cut through into it for the fan during the second fix. However, it appears that the hole was never cut!

I believe that the spigot you can see should be the other way up, and protrude through the hole so that it sticks up into the duct. If so, that may explain why the fan was butchered to make it fit.

The horizontal duct should slope slightly down towards the outlet, so any condensation takes a similar route (condensation traps are fitted in vertical ducts) The raised spigot should be sealed in place with silicone to prevent any condensation from the duct running back through the fan.

Sometimes this method is used so that one duct can be used with several fans. In which case backdraft shutters would be required.

Untitled

• stem
• 8 Apr 2013
• 1

If the fan is not pulling air through it, because the outlet is blocked, there will be little if any air resistance and so the blades and the motor will operate faster than normal and accelerate wear. (Similar to what happens when you block off the inlet to a vacuum cleaner and the motor speeds up)

 

[trevalex]

To me, it looks like the duct would likely have been installed at the time of building construction and a hole should have been cut through into it for the fan during the second fix. However, it appears that the hole was never cut!

I believe that the spigot you can see should be the other way up, and protrude through the hole so that it sticks up into the duct. If so, that may explain why the fan was butchered to make it fit.

The horizontal duct should slope slightly down towards the outlet, so any condensation takes a similar route (condensation traps are fitted in vertical ducts) The raised spigot should be sealed in place with silicone to prevent any condensation from the duct running back through the fan.

Sometimes this method is used so that one duct can be used with several fans. In which case backdraft shutters would be required.

Untitled

• stem
• 8 Apr 2013
• 1

If the fan is not pulling air through it, because the outlet is blocked, there will be little if any air resistance and so the blades and the motor will operate faster than normal and accelerate wear. (Similar to what happens when you block off the inlet to a vacuum cleaner and the motor speeds up)

Sorry for late reply. This makes sense to me ..
Reckon I could ask the management of the building to rectify this or would it be the leaseholders responbilty?

 

[trevalex]

My dad also mentioned a good trick.
Take a match and hold it up to the ducting so its smoking.. the smoke should be naturally pulled up the duct.
This will tell you if the duct is allowing a free flow of air.
Obviously if its blocked then steam will just build up in the duct (especially if the previous fan was knackered).. then your steam has no where to go so it will condense back into your bathroom.

Oh and just worked out the guarantee on the flat expired so it will be a whip round scenario for all members of the block to get it fixed.

 

[stem]

It's quite likely the match test would appear to work, you don't require much suction to pull in smoke. Any tiny gap in the fan casing would allow enough air through the fan to pull the smoke from a match in. If the duct is closed, it wouldn't be extracting the air out of the room, but it would allowing it to seep back into the room through joints in the fan casing.

A better test is to use a square of thick paper just big enough to cover the entire fan inlet grill. With the fan running, there should be sufficient suction to hold it in place.

Regarding the incorrect installation, the warrantee shouldn't matter. Someone has been paid to install the fan system and they haven't done it correctly, so should put it right. Assuming someone is able to contact them.

Also, you may find that the other flats fans have been installed correctly and so they may not want to contribute.