Advice Needed on Bathroom Extractor Fan

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Hi all,

We have a downstairs bathroom which has a bath and shower and we have no kind of extractor fan fitted in the room. The only kind of vent is a celling mounted grill that is located above the bath and is connected to a flexi pipe to an outside grill on the wall as the bathroom has 3 outside walls.

The other vents are window vents and the windows which we have open alot and the heating source is a large double radiator.

The main problem we have is the amount of steam which fills and stays in the room while running a bath or shower and we have just noticed a small amount of mould next to the grill mounted on the celling and also the tiles get very wet if the bathroom is used. The images below show the location of the vent grill etc above the bath.

If anyone can give me an ideas on if i should fit a celling mounted extractor fan and if i could use the location where the grill is already. The flexi pipe go's up by about a foot then across to the outside wall.

I have no access to the celling Void above the bathroom as a hatch was never installed and i also dont want to spend to much on doing this.



Many Thanks
Chris
 
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If you have no access to the duct, how do you know what kind of condition it is in. It would also be better if the duct was thermally insulated along it's route.
Also if you were to install an electrical extractor, you would require access into the void, to route cables.
Ideally you would need to calculate the size of fan best suited for room and an overrun facility on the fan normally triggered by the light being operated but you could also have a humidistat, which detect when humidity is high, generally over 60% and then the fan would kick in.

The circuit/equipment would likely require RCD protection.
 
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Ideally you would need to calculate the size of fan best suited for room
The trouble is that all the "calculators" and tables I've ever seen will give you a pitifully useless fan, based on the assumption that 15-20 air changes per hour (or, even worse, the figures in AD F) are actually enough.

Better to get the most powerful fan you can fit or afford. As long as it doesn't pin animals or small children to the grille, or suck the door of its hinges, it'll be right.




and an overrun facility on the fan normally triggered by the light being operated
But then the fan will come on if you only go in to wash your hands, clean your teeth etc.


but you could also have a humidistat, which detect when humidity is high, generally over 60% and then the fan would kick in.
Dubious reliability?

Chrisb - what type of shower is it? Do you use the bath?
 
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You could fit a ceiling mounted fan and the light is close enough to fish the cable to fan without ceiling access, though it would only mean lifting a board in the room above.Ideally should be a permanently open vent in the room to the outside.I would avoid humidistat as they react to humidity and you need to remove it before it has chance to build up.
 
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Hi

Its just a Mira shower over the bath and yes we use both.

There is no room above the bathroom. Its an extended part of the house so it only has a slope roof with roof tiles on.

Chris
 
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we use both
Triggering the fan with the shower is easily accomplished. The bath is trickier - not so much to make it start, but keeping it running long enough. A temperature switch on the hot feed to the taps would be a good trigger, and that would stay open for a while after you stop running the water, and then the fan would stay on until its delay time ran out - question is would that be enough?

Maybe a manual switch to work the fan would be best. You will get into the habit of using it.


There is no room above the bathroom. Its an extended part of the house so it only has a slope roof with roof tiles on.
You must get access - you cannot vent an extractor fan through an uninsulated duct.
 
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There is no room above the bathroom. Its an extended part of the house so it only has a slope roof with roof tiles on.
You must get access - you cannot vent an extractor fan through an uninsulated duct.[/quote]
Never had a problem with uninsulated duct as long as the fan is powerful.
Simple ceiling mounted sensor will operate the fan when ever the room is occupied, far more effective than a switched fan.
Good ventilation will prevent mold etc, so not just used when showering or using bath.
 
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Simple ceiling mounted sensor will operate the fan when ever the room is occupied
Even when not needed.


Good ventilation will prevent mold etc, so not just used when showering or using bath.
Would you advise PIR operated powerful extractor fans in every room in the house?
 
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