Loft Conversion: Bathroom Extractor fan, is this ok?

[da3533]

Hello

need to choose a spot for my extractor fan... wanting to put it in between the rafters but the PIR insulation will be there.... so I thought to ask whether it would be compliant to situate the fan onto the back wall leading to the storage area also making it easier to duct through to the nearest wall vent.

see pic.
Please note: bath rub/shower will be on the left as marked in green and toilet/basin vanity will be on the right.

 

[JohnD]

You need the shortest and most direct run, as ducts can hold water from condensation (especially if they are the ridged, flexible type)

And water vapour is lighter than air so you need the extraction vent to be at ceiling height, and preferably over the shower.

 

[da3533]

i dont think it can be over the shower in my case as the height between the floor level to ceiling is 2.10m... regs state it needs to be minimum 2.25m if in zone 1.
so I might just situate it next to the shower screen, outside... connect straight into the roof using a Single Pantile Roof Vent (from the extractor fan to the roof is just 10cm away...)

this would be fine right? has a 4cm adapter to connect

 

[^woody^]

You would fit a compliant SELV unit or a remote inline fan.

Its no good compromising with a fan that is not performing how it should

 

[da3533]

You would fit a compliant SELV unit or a remote inline fan.

Its no good compromising with a fan that is not performing how it should

these can fit above the bathtub even though height is less than 2.10m?

 

[^woody^]

With a suitable IP rating yes

 

[JohnD]

An inline fan is fitted in the duct, so need not be at the inlet grille. They can be much more powerful than a surface fan.

 

[da3533]

An inline fan is fitted in the duct, so need not be at the inlet grille. They can be much more powerful than a surface fan.

Thanks, will do this. however, I have to cut a tunnel into the PIR insulation in order to put the 100mm ducting through to the bottom where it will connect to the inline fan, is this the correct way? do I use insulated ducting instead?

 

[JohnD]

Don't understand

Can you draw a sketch?

 

[da3533]

oh ok, here is a pic i just took.
See below. the red dot would be where the ventilation grill is. the red line is the 100mm ducting. however, this can only go between the rafters where the PIR insulation board suppose to fit in... so do I cut a 100mm tunnel into the back of the insulated board, and use insulated ducting ....

 

[JohnD]

Why do you have such an enormously long duct?

 

[da3533]

Why do you have such an enormously long duct?

that pipe has been in the loft for ages, its not connected to anything .the red line I drew just so happened to seem to connect to it but doesn't

 

[da3533]

and the red line where the ducting is to go is about 1.2m down, may seem long int he picture but its not.

 

[da3533]

so from looking at the pic above, do I cut a 100mm tunnel into the back of the insulated board, and use insulated ducting? or normal ducting?

 

[JohnD]

are you taking it down the roof slope and out through the eaves?

I'd have thought a roof vent would be simpler, provided you have a competent roofer who can make a hole without causing leaks.