Extractor Fan replacement - ensuite

[Sidewinder]

I see what you mean, but when the fan is not on natural convection will tend to be up into the above ceiling space, taking humidity with it. I would only be happy if such a  ceiling vent was ducted from outside.

The ceiling/floor/loft space is not sealed anyway.

If the fan is on at all times humidity is created then if the system is correctly designed, the levels should be correctly sorted and such should not transfer any volume of moisture into the void space.

 

[martyj]

Because it's an ensuite, what I do is shower with the door very slightly open so there is air intake, then the fan has a 20 minute run on and I leave the door fully open. Seems to be working ok so far?

 

[Murdoch]

Because it's an ensuite, what I do is shower with the door very slightly open so there is air intake, then the fan has a 20 minute run on and I leave the door fully open. Seems to be working ok so far?

How much of a gap do you have at the bottom of the door? Turn the fan on , close the door and standing clos to the inside of the door you should be able to feel the air passing over your feet.

if you don’t then shorten the door by about 5 mm to create the necessary air gap / flow.

 

[Doc Hudson]

Hello MartyJ, welcome to the forum.   Are there any other openings in the room such as vents or windows. If the room has no other openings,  is the fan operating correctly with a suitable duration of run-on timer?  (building reg's recommend 15minutes). How long is the ducting before the vent reaches outside? Many people have a fan that is only on while they are in the room that then goes off immediately they leave. This will not have sufficient time to remove residual moist air / steam so will promote mould growth etc. Also to extract air out, there must be an equivalent vent size letting air come into the room. (otherwise the fan is trying to create a vacuum.)  Typically with an enclosed room this requires a 10mm gap under the bottom of the average 760mm door to allow a standard 100mm diameter extractor vent pipe to pull in the same volume of air. Again many people have plush fitted carpets in the adjoin room so there is no inlet ventilation to the en-suit. (a simple test to check the gap is can you poke you fingers under the en-suit door from both sides?). Providing you have appropriate inlet ventilation, adequate timer run-on and the extract duct is not several meters long though the loft void, then the fan should do the job. It looks like a Greenwood Airvac to me?  But if there are several metres of duct to reach the outside it would be better with a higher power in-line centrifugal fan. 

Doc H. 

How much of a gap do you have at the bottom of the door? Turn the fan on , close the door and standing clos to the inside of the door you should be able to feel the air passing over your feet.

if you don’t then shorten the door by about 5 mm to create the necessary air gap / flow.

Already asked this back on 18th same day of original post,  (and 100mm dia duct pipe area approx. 78cm2. average 76cm door will need at least 1cm clear gap at the bottom),  But then OP said he leaves the door slightly open anyway so gap unlikely to be too small with door ajar.  

Doc H.

 

[Sharpend]

@Sidewinder

your point about a building being sufficiently leaky, is that the case these days with new builds, I know a few years back that New builds were air tested and had to be as close to negligible as possible, I remember that windows no longer had vents, all crevices and joints were sealed air tight, mastic and sealant was king, it got so bad we used to joke that if you left you tool box open long enough it’d get sealed to stop the air escaping with you when you left! 

Has this changed? I always thought that it was a bad idea as a building needs to breathe, what happens in the event of a gas leak in a sealed building, a rather exquisite explosion? 

 

[Sidewinder]

@Sharpend, you are fully correct with your ideas about new buildings, they are air tight, which is lettuced imho.

I took this as an older building.

I dread to think what would happen wrt a gas leak!

Or what about a CO leak from a boiler/fire etc., no gas exchange, just builds up...

 

[Sharpend]

what concerns me is that if us mere tradespersons can see this eventuality why can't those that are supposed to be more aware? it just shows how useless we have become, totally reliant upon computer models and little brain activity. 

Question is would the LFB pick up and run with this like they have with electrical issues? they will be the ones who ultimately bring it to the attention of those that may listen.

 

[Murdoch]

@Sharpend, you are fully correct with your ideas about new buildings, they are air tight, which is lettuced imho.

I quite agree. How many rental properties now have issues with mould and damp ? 

I see see a few and the common denominator is lack of ventilation .....