Extractor fan installation?

[Gareth]

Hopefully someone will be able to provide advice.

I've installed a 100mm extractor fan in a small bathroom. The fan is capable of extracting 93m cubed per hour. The room is *very* small: toilet, bath and shower attachment to bath taps (combination boiler) with no room left.

The extractor fan seems to work well when the bath is being used but it isn't functioning effectively when the shower is used: the condensation is very apparent and has causing water/damp/condensation damage to Artex in one corner of the small room (I tried to repair the Artex damage with filler but that too has flaked because of condensation).

Can anyone tell me if this is a common problem? (If so, why does shower use cause this when bath use doesn't?)

If a bigger fan is needed I don't feel at all confident installing it - cutting holes in the ceiling and even roof for larger ducting. Does anyone know which trade would install the ceiling fan and ducting. I think an electrician wouldn't deal with the ducting and a plumber wouldn't deal with the electrics?!

Gareth.

[meow2222]

Some 4" fans are better than others. Throughput will be determined by the resistance to air flow into the room just as much as by the fan. To put it another way, fans cant be expected to achieve the stated figures. Showers put out much more steam than baths. If there is no wide open air input route, a grille in the door may solve it. Extacting air by teh shower obviously makes more sense than elsewhere. However in the medium run a humidistatic dehumidifier will cost you less thsn a fan.

NT

[Chris J Dixon]

The moisture in the air gets there by evaporation. The amount of evaporation is related to the surface area of water exposed to the air. The surface area of the bath (plus some wet skin) is very much less than that of all the water droplets falling from the shower head. The finer the spray, the greater the effect. The motion of the droplets further enhances this.

Chris

[Dave Liquorice]

Can 93m^3/hr of air get in when the room is in use and/or the door closed? Does the fan run on after use of the room? If so for how long?

[The Medway Handyman]

An excellent point. If you want 'air out' you have to have 'air in'.

In the past I've sold lots of hot water pressure washers that were installed in sheds/buildings/containers.

The purchasers always seemed to ignore the advice given and made the enclosure damn near airtight. Result? No boiler ignition because there was no airflow.

A grill in the door solved that problem, so it should work well in a bathroom.