Extractor fan position

Grenage

Our new place doesn't have an extractor fan in the bathroom; I'm decorating, so I might as well do it now.

I believe they are normally positioned opposite the point of air ingress - in this case the door.  Pretty much the only steam generated comes from the shower, so I was tempted to place it above that.  Only down side is it's an extra 3-4 metres of ducting.

I can't imagine it will make much difference, but thought I'd sanity check.

Lorian

The door being next to the shower is not ideal.

Assuming you can use an inline fan mounted up in the loft so there is no electrics near the shower I would put the duct above or near the shower. An line is much more powerful.

 It's costs a bit more but you could use solid pipe ducting to compensate for the longer run, trying to avoid right angle bends. The pipe should be well lagged to stop condensation forming inside it and ideally should run down towards the external grill.

You'll need an electrician or be competent to make sure you have a 3amp fused supply if fed from the lighting circuit and a 3 pole isolating switch outside the bathroom door.

You need to think about how you will start and stop the fan too - humidistat or pull cord or triggered by the light switch with delay off.

When cutting in to the ceiling always check for cables running above the ceiling first.

Grenage

I've fitted an in-line fan before, and I'm fairly competent with electrics.  It's just the positioning I was pondering.

I'll be putting the isolator next to the fan, so that will be in the loft.  I used a timer last time, but I'll probably use a humidistat this time.

I'm not sure if having it above the shower will make much difference with the position of the door.  The ceiling is very high so there's well over a metre gap above the screen.

Ectophile

If it's a long duct, make sure you get a fan suitable for blowing through a duct - one that can produce a higher pressure.  That's especially important if the duct has bends.  The basic axial fans can't always do it.

Baldytyke88

Grenage said:

I've fitted an in-line fan before, and I'm fairly competent with electrics.  It's just the positioning I was pondering.
I'll be putting the isolator next to the fan, so that will be in the loft.  I used a timer last time, but I'll probably use a humidistat this time.

I'm not sure if having it above the shower will make much difference with the position of the door.  The ceiling is very high so there's well over a metre gap above the screen.

I had 2 quotes for fitting a fan, one wanted to fit it above the shower in the ceiling, the other guy was going to drill a hole in the wall next to the shower.

Mr.Generous

My 2p worth, I wouldn't call that a long run, a std bath is 1700mm - about 5'6" so you might be running 8ft ducting to the fascia boards. Perfectly normal for an inline fan. I have used timer run on fans for many years at home, and in rental property without issue. A couple of years ago I switched to humistat fan in one rental and it stopped working. A quick look revealed scorching on the PCB, not ideal, it could have gone up in smoke. No charring around wiring points so presumably just a faulty fan. And then the replacement did the same thing. Also humistat fan. I stuck a timer fan in and next time I saw my electrician son-in-law mentioned it to him. Maybe a complete coincidence, but he showed me pics on his phone of a nasty bathroom fire that started in a humistat fan. Very small sample, but I'm steering clear.

Lorian

Grenage said:

I've fitted an in-line fan before, and I'm fairly competent with electrics.  It's just the positioning I was pondering.

I'll be putting the isolator next to the fan, so that will be in the loft.  I used a timer last time, but I'll probably use a humidistat this time.

I'm not sure if having it above the shower will make much difference with the position of the door.  The ceiling is very high so there's well over a metre gap above the screen.

Ok. Manrose are my favourite fans but they aren't the easiest to get a tidy finish into the wiring in the PCB. Bootlace ferrules trimmed back make a good connection in the blocks.

You need at least 500mm of pipe either side of the fan.They are better sucking rather than blowing so dont have it too close to the inlet.

 They tend to not have backdraught shutters built in so factor in one of those in the pipe run. Make sure the orientation is right to open. Some rely on gravity to close rather than springs 

Mount the fan on rubber to keep vibrations down.

Click brand has a modular fan
Isolation switch and fuse holder that can fit in one matrix front and single backbox, quite neat job.

If you use the humidistat version and have the isolator in the loft consider a pull cord in the bathroom to turn it off at night as an over-ride for any noise annoyance.

Grenage

Thanks for the input chaps.  I installed the last fan on bungee cords and it eliminated any vibrations, although that was using flexible ducting.  I'll use solid this time, so I might use a very short piece of flexi either side to decouple.

ThisIsWeird

I'd suggest that 'distance' isn't an issue, as it can easily be compensated for with larger ducting - 5 or even 6" - and using a smooth rigid type. And, the best location will remove the moisture at source.
Especially given that you have a high ceiling, I would definitely position the grille above the shower - that is surely the best location by far.

The bathroom door location isn't an issue - it'll presumably be shut during use, when the fan will be doing the bulk of its work. In summer, good chance the window will be cracked open, and likely to be trickle-venting for all, or most, of the year, so I'd consider these air-supply sources to be a minor consideration here - they will just supply a gentle cleansing waft to replace what's being extracted. Priority will be to get rid of the moisture asap, before it condenses anywhere.

But, other things to consider are noise - will anyone upstairs hear it? I fitted a Manrose inline in our eaves, suspended on cords from the rafters, but we still hear it to an irritating degree in the adjacent upstairs bedroom.
Adding a humidistat is a good idea, but carries the risk of it running when you just don't want it to - eg noise at night. Ditto for timers.

I plumbed for now't with mine, just a separate pull cord switch so it's used only when wanted. We just leave it running after showers, and whoever passes the bathroom next turns it off. 

These days, of course, there's all sorts of sophisticated Smart control, like Bluetooth, humidity, time, auto-adjust speed, and - yup - smell. Some will run constantly to provide a background level of ventilation, with zero noise and minimal power.

Kiran

An inline extractor mounted in the loft and you can have multiple extract points. You can fit one directly over the shower and one above the WC for maximum effect. If you get one that is reasonable power, this is where inline beats the through wall or ceiling mounted. Sufficient air changes will trump position in this instance

Grenage

Thanks guys, I have been convinced. 

I'll add a 150mm unit and feed from above the shower.  I'll also add a dedicated switch and run it separately; less to go wrong!