Windowless bathroom EXTRACTOR FAN

[ElsieJ]

Please accept that this is not a duplicate post, but as I have information about the current extractor fan I wonder if any advice could be given regarding the suitability.

Fan is currently is disconnected because of water collecting behind fan in the duct.

Current fan is: Xpelair 2001, 220-240V, 15W max, model no. 90841AW, outer casing measures approx. 6 inches square.

Property is first floor flat, with one flat above and a pitched roof. Flat has no windows; is approx. 400 cubic feet, and has a bath and a shower cubicle. Fan outlet is at top of wall next to the shower cubicle, and has to travel approx 12-14 feet to outlet on top of roof, along a vertical duct.

 

[stem]

You will need a minimum of 15 litres a second extraction rate for a bathroom. This rate equates to 54 cubic metres/hour or 32 cubic feet/minute, depending which units the manufacturer uses to specify their products performance.

In your case, because of the duct run, select a fan with a centrifugal impeller, instead of the traditional fan blades, centrifugal blades generate additional pressure to overcome the pressure losses in the ductwork.

Because the duct is vertical, any condensation that forms on it will run back down the duct and into the fan, this is a particular problem if the duct passes through un heated loft. So the duct must be lagged and fitted with a condensate trap with a drain to remove the collected condensation. You will also need a cowl to prevent rain entering.

Electrically speaking bathrooms are now separated into divisions, click here for details. So the fan you purchase must be suitable for installation in the zone you are locating it it.

To work properly, the fan should be sited at the opposite side of the room to where replacement air comes in, which as you don't have a window, will probably be the door. Make sure that there is a gap underneath it to allow air in. This way air is drawn across the whole room ventilating it effectively.

 

[Taylortwocities]

There is a fan size calculator here http://www.tlc-direct.co.uk/Technical/Ventilation/Ventilation4.html

Don't forget that to efficiently pull air out of a room you must allow an equivalent amount of air into the room.