Fitting a bathroom extractor fan.

[bluenun20]

Hello all,

I would like to reduce the humidity in my bungalow and am thinking of getting an extractor fan fitted in my Bathroom.

Is it best to position the extractor fan above the bath or in the middle of the room?
The Bathroom is only 6 foot, 1.8 meters wide.

I was going to route the extracted air through the ceiling into the loft space and out through the cavity wall rather than go out through the roof tiles.
Is that a good or bad idea?

Should the extractor fan be fitted to the bathroom light which is a 3 wire connection?

 

[PrenticeBoyofDerry]

Best place to locate the extraction vent, would be where most of the condensation is going to be. But ideally not near any external source of air.
The fan does not have to be connected to the bathroom light, but normally are. It is often desired that the fan comes on with the light and overruns when the light is turned off.
As the work is in the bathroom, you need to check that the work is deemed notifiable to building controls and whether RCD protection is required as additional protection for the location and any newly buried cables.

 

[ericmark]

For a new build there are regulations mainly in Part F, but also Part P you may as well follow them even if not forced to, they talk of windows and if the window opens no need for fan, if no window then fan can run on light switch, if however there is a non opening window then you need some way to switch on fan without lights, this could be a simple pneumatic push switch or a PIR.

The problem with any fan is the air needs to be replaced from some where, again building regulations warn against fitting fans if there are open flue fires in the house. Open flue does not mean old open hearth fire, it means the fire draws air from the room, not outside, most central heating boilers have a balanced flue and are OK, some solid fuel fires have ducts to draw air from outside, but many draw their air from the room. The fitting of draft excluder's and security doors which seal very well means that houses are more and more likely to end up below atmospheric pressure when using extractor fans including tumble driers. So depending on house you may need vents in bathroom door or even a heat recovery unit.

There are two basic types of heat recovery units, those which both blow air in and out, and those with blow it out and rely on the depression in the room to draw the air back in, the latter look like simple extractor fans, the heat exchanger is built into the pipe going through the wall, also with that type you want the door to be well sealed.

Drawing the replacement air from outside in the main means the air is dryer so it dries out the bathroom better, relative humidity changes with temperature, so if at 2°C it is 95% once warmed up to 20°C it's more like 40% which is considered too dry. So they work better than a simple fan.

However drawing air across the room from under door to extractor is different to sucking air from room and blowing it back in from the same unit, so the type of unit has to be selected first then work out where to put it.

Part P means in the main it's not worth fitting as a DIY job, so better asking the electrician who is going to fit it for advice.

 

[bluenun20]

Thank-you PrenticeBoyofDerry and ericmark for your replies.

It is not quite as simple as I had initially hoped
I was going to do the fitting of the fan and pay an electrician to wire it up.

I do have an opening window in the Bathroom so maybe no need to install an extractor fan.
I got the idea after visiting my Mother's flat, they have no opening window in their bathroom.

There are no open flues here, I have storage heaters as my only heat source in this 1990 Bungalow.

 

[PrenticeBoyofDerry]

Just because you have an opening window in the location, does not exclude you from having or needing any additional extraction for condensation.

Building regs require mechanical extraction, if no opening to an external air source. Not that there cannot be one if you have one.

And as you have no open flues that is not an issue, and if you did that does not exclude extractor fans, but some testing would be required.

 

[JohnW2]

Part P means in the main it's not worth fitting as a DIY job, so better asking the electrician who is going to fit it for advice.

Why do you say that - is it notification you're thinking about? If so, at least in England, the work would only be notifiable if the fan were within bathroom zones, which I imagine is relatively unusual.

Kind Regards, John