Extractor Fan Recommendations

[chuckalicious]

Going to be running an humidity controlled extractor fan from the ceiling in my bathroom above my shower, into the loft and out the gable end wall. I would want the facing flush on the ceiling it at all possible. Bathroom is 2.2w x 3.5h x 2d (metres).

Doing it this way sadly means a duct length of 4.5m with 1 90 degree bend. It is either that or I have to get it vented through the roof and involve roofers etc which Id prefer to avoid.

Thanks.

 

[^woody^]

An inline centrifugal, and you might need to go up to a 150mm unit and duct for that distance - particularly if the outlet is on a wall that gets the prevailing wind.

 

[chuckalicious]

Thanks Woody. Take it wouldn't work well to step down to 100mm at the vent as that's the core bit I have!

 

[endecotp]

Try it and see; if it's inadequate you can consider enlarging the vent.

Humidistats are not much liked by people here. I don't think you get humidistat inline fans (and you do want an inline centrifugal or mixed-flow fan). So you'll need a separate humidistat. But try first with a standard timer fan and see if that works for you.

 

[theprinceofdarkness]

You will get condensation within the duct, so run it vertical above the bathroom, then turn it over so the long length of it slopes downwards. So condensation in the first part drips back down into the bath room, then 4.5m worth of condensation drips down the slope and out through the grill. Don't use flexible ducting, any low points will slowly fill with water and finally break something and tip its contents onto your ceiling. This happened to a mate of mine.
Its only wet air, so you can dummy something out of DPC and tape providing its resting on a plank to support it and to give it the slope, just do it. The other point if your house is made with lime mortar avoid the ali ducting, minute bits of lime will blow about and rot through the ali. Happened to my set up within a couple of years.
Frank

 

[chuckalicious]

Ok will need to check out fan options. It needs to be on when the shower is being used, but it is a mains shower so no switch to also turn on the fan. Other people in the house will not remember to do it manually...

 

[^woody^]

If the duct is insulated, then it won't get any significant internal condensation.

Yes you should be OK with a 100mm outlet with a larger fan and duct.

Really though just have a read of the chosen fan's guidance, as a better 100mm fan may be as effective as a not so good 150mm unit. See what performance they state with 6m of duct.

Don't forget to allow an air inlet into the bathroom - 10mm gap at bottom of the door normally.

 

[theprinceofdarkness]

Yah, I over came this problem by using a clip on current transformer (part of an obsolete Smart meter) and some electronics to automaticaly switch the fan timer on. One fan 10 Min timer when just using toilet light, 40 mins when fired up from the shower heater.
Frank

 

[chuckalicious]

Ok thanks everyone. Glad it can be done with that sort of run. I had wondered about condensation so will take that into account too, even if just for belt and braces approach. Just the powering on method to figure out.

 

[chuckalicious]

Just looked at humidity controlled switches. Perfect for the job but I foresee issue as all my bathroom walls are tiled floor to ceiling. Can't see how Id get power to it unless I can mount it on the ceiling.

 

[endecotp]

There have been other threads about how to turn on a fan when the shower is on automatically, try searching.

 

[ban-all-sheds]

it is a mains shower so no switch to also turn on the fan.

I assume you mean it is a mixer, with H&C water, hot coming from a cylinder or combi boiler?

If so get a temperature switch and fix it to the hot feed pipe. Shower turned on - a few seconds later the fan will start. Depending on how much overrun you need, and how sensitive the switch is, it might stay on long enough after the shower stops to keep the fan running for long enough. Or it might not.

 

[JohnD]

There have been other threads about how to turn on a fan when the shower is on automatically, try searching.

The simplest and most common method is to have the fan come on automatically with the light switch, and an overrun timer. This will also ventilate the bathroom after the WC has been used.

More complex and expensive methods of switching are available.

Modern fans use tiny amounts of electricity, and can be very quiet.

Some of these (towards the bottom of the page, not the pathetic 80 cu.m/hr ones) are powerful and quiet. Look at the extract rate and the noise ratings.
http://www.tlc-direct.co.uk/Main_Index/Ventilation_Index/4_Inch_Fans_Duct/index.html

 

[ban-all-sheds]

The simplest and most common method is to have the fan come on automatically with the light switch, and an overrun timer. This will also ventilate the bathroom after the WC has been used.

1. Another meaning of "simplest and most common" is "thought-free, this-is-the-way-it's-done-because-this-is-the-way-it's-always-been-done".
2. Not all bathrooms always need a light turning on in order to use the shower or fill the bath.
3. Not all bathrooms need a fan to operate whenever someone goes in there, no matter why they are there.
4. Not all bathrooms contain a WC.
5. Not all uses of a WC generate a need for ventilation.

Some of these (towards the bottom of the page, not the pathetic 80 cu.m/hr ones) are powerful and quiet. Look at the extract rate and the noise ratings.
http://www.tlc-direct.co.uk/Main_Index/Ventilation_Index/4_Inch_Fans_Duct/index.html

Or, if he can make the vent sizes larger - http://www.tlc-direct.co.uk/tcl/search.tcl?search=td500&Submit=Search

 

[JohnD]

More complex and expensive methods of switching are available.

And some people like to make life complex and expensive.