Suitable extractor fan

[littlespark]

Not specifically electrical, but best way to minimise condensation in a shower room. Asking for a customer.

Background.
Customer is a neighbour. Previous owners of house had broken through between a downstairs WC and a large cupboard and fitted in a shower cubicle.
There is an existing 4” extractor fan directly through the wall, which goes on and off with the lights… no run-on.
They don’t want to open the window while they have a shower, as it faces the street and they don’t want to flash their bits to passing motorists.
They complain that the room is forever needing painted.
They believe a stronger fan is required, and they want a heater put in… (no nearby power, so maybe a small wattage heater off lighting circuit?)
Would either help at all, or is the best answer to just ventilate the room?
If they don’t want to open the window, then a fresh air inlet? Just another hole through the wall with standard grills?

 

[nicebutdim]

Humidistat fan or maybe heat recovery unit so they don't blow that nice warm air out through a wall?

 

[Jim_e_Jib]

How tightly does the door to the room fit? Could it be that a bit skimmed off the bottom will allow more air to enter and the fan expel more damp air?

As above, I think upgrading to fan with an overrun/humidistat would be a good idea.

 

[Pretty Mouth]

Poor insulation can be a big factor in condensation. Are they getting a lot of mold forming?

 

[David Prosser]

Opening a window isn’t always a good idea, especially in winter. If it's cold and there’s a lot of steam about it can cool the air down rapidly and makes the water held in the air condense out quickly and form droplets on the walls, windows etc. Better to remove the water laden air if possible. Unless it's some sort of passive house then there will be plenty of air moving through the bathroom. A heater to keep the air warm for longer will definetly help.

 

[DPG]

If the room is fairly well sealed then cut a slot low down in the bathroom door and fit rectangular plastic vents on either side. The extractor fan can only extract the damp air if enough replacement air can be sucked into the room to replace it.

 

[littlespark]

Thanks for all the input.

I know it’s a 2012ish new build… not a passive house.
I might swerve it a bit… I’m not sure if the conversion was done to regs, and it could be a minefield to sort out. It’s now a room containing a bath or shower, so zones apply…. Whereas it was initially just a WC.

I might suggest the air vents through the door… the fella is a joiner to trade…
And question if the paint they’ve been using is suitable for bathrooms or just regular emulsion.

 

[brianmoooore]

There is an existing 4” extractor fan directly through the wall, which goes on and off with the lights… no run-on.

Surely the last three words above is the first thing to be addressed.

 

[littlespark]

Surely the last three words above is the first thing to be addressed.

They leave the switch on.

 

[brianmoooore]

In that case, lack of wall insulation is causing the problem. Walls are so cold that water is condensing out before the fan can shift it, and so cold that it won't evaporate again even if the fan does run on.
Even 25mm of Celotex can make a lot of difference.