Humidistat Advice

jonny2510

In addition to my other thread, re. the extractor hood, I'm also looking to get a humidistat fitted in the bathroom (again to try to alleviate some of the condensation problems we've been having).

I've had a builder round (a friend of the family, so someone we can trust) who's recomending fitting an extractor fan through the roof in the bathroom, near the shower (the bathroom is tiled all round, and we dont want to disturb/damage them).

He's going to fit a drainpipe I thing he said, through the roof slates with a covered cap over the top. He's suggested I get an electrician to wire up the humidistat.

Can anyone suggest a good humidistat that will do the job of removing as much moisture from the air as possible?

Would I need to buy a kit, to fit it to this pipe?

Am I missing anything obvious?

Mikeyorks

You need a good quality (if you're going to this sort of trouble - something off the shelf at e.g B&Q is generally underpowered) in-line extractor fan. I wouldn't go for a humidistat control - but a timer model wired to the light and set to run on after the light is off. You merely flick the light on and immediately off - if you want to bring the extractor in without wasting the light. Good for 'odours' as well.

The configuration will be the vertical equivalent of the horizontal diagram at the top of this page :-
http://www.tlc-direct.co.uk/Main_Index/Ventilation_Index/4_Inch_Fans_Duct/index.html

.... but because you're putting it out into free air on the rooftop (rather than less turbulent air from the fascia / soffit) - I'd include a non-return widget in the pipework - all on this (TLC) site if you look around the Ventilation links.

Measure your bathroom and work out the cubic metres (total width x length x height) multiply that by 10 (ie air changes per hour) - and that's the capacity extractor you need.

This one :-

http://www.tlc-direct.co.uk/Products/SLTD250T.html

... moves 250 cu metres / hour and is relatively silent when mounted above the ceiling (across the joists on a board - and put a sheet of foam between it and the board to kill off any transmitted vibration.) Don't buy the kit version - buy the flexible pipe etc separately. Get the aluminium flexible ducting if dormice visit your loft - as the little sods love chewing the white plastic stuff and will turn it into a colander overnight. My kitchen extract pipe (just changed to aluminium) pays testimony to that - but the bathroom one has never been touched

All you see of this is a little white grille in the ceiling. Consider the one with the light (comes in white / brass / chrome) particularly if the shower is in a cubicle?
http://www.tlc-direct.co.uk/Products/BGSLW.html
Either way - mount the extract grille in the ceiling very close to where the shower is - as that creates most steam. And this extractor will remove most steam 'in flight' - without allowing it to get around the rest of the room and condense.

Timed extractor and low voltage shower light are an easy wiring job (electrician or competent person) - needs the switched live to the bathroom light and a permanent live re the timer overrun (hence 3 core + earth).

jonny2510

Mikeyorks wrote:

You need a good quality (if you're going to this sort of trouble - something off the shelf at e.g B&Q is generally underpowered) in-line extractor fan. I wouldn't go for a humidistat control - but a timer model wired to the light and set to run on after the light is off. You merely flick the light on and immediately off - if you want to bring the extractor in without wasting the light. Good for 'odours' as well.

The configuration will be the vertical equivalent of the horizontal diagram at the top of this page :-
http://www.tlc-direct.co.uk/Main_Index/Ventilation_Index/4_Inch_Fans_Duct/index.html

Any particulare reason for recomending the timed fans over humidistats?

The room (at max is) 2.7 long x 2.2 high x 2.15 m wide (=12.8 Cubic metres). So by my reconning, I need approx 130 cubic metres of air shifted per hour.

Would this be sufficient or should I just bight the bullet and do it properly, buying either this 160 cubic metres / hour model, or even aim for oiverkill and get the 250 Cubic Metres / hour version for just £10 ish more

.... but because you're putting it out into free air on the rooftop (rather than less turbulent air from the fascia / soffit) - I'd include a non-return widget in the pipework - all on this (TLC) site if you look around the Ventilation links.

do you have a link to this, as I can't seem to see it anywhere?

Don't buy the kit version - buy the flexible pipe etc separately. Get the aluminium flexible ducting if dormice visit your loft - as the little sods love chewing the white plastic stuff and will turn it into a colander overnight.

I suppose if I'm doing it properly, alluminum would be the way to go. To avoid the mice thing if at all possible. I've never seen a mouse in the house, but I suppose it's better to be safe than sorry.

All you see of this is a little white grille in the ceiling. Consider the one with the light (comes in white / brass / chrome) particularly if the shower is in a cubicle?

http://www.tlc-direct.co.uk/Products/BGSLW.html
Either way - mount the extract grille in the ceiling very close to where the shower is - as that creates most steam. And this extractor will remove most steam 'in flight' - without allowing it to get around the rest of the room and condense.

the shower is in a cubicle. The fan vent is either going to go in the cubicle itself, or just outside it. I'm guessing in the cubicle would make it more effective.

Unfortunately, it's gonna be real awkward to fit. The bathroom (on the second floor) sticks out from the rest of the house, and has it's own slanted roof. The loft void above the shower (where the fan would be located) does not appear to be accessible from the main loft, meaning the builder is proposing removing roof tiles, fitting a soil pipe (with cover), and then getting the electrician to wire (and maybe even fit) the in line fan himself.

Quite how either of them will do this is beyond me, as I don't know how they'll get access to the void, without wrecking the whole ceiling.

Timed extractor and low voltage shower light are an easy wiring job (electrician or competent person) - needs the switched live to the bathroom light and a permanent live re the timer overrun (hence 3 core + earth).

Am not quite sure what 3 core + earth is. I'll hopefully be getting an electrician in to add a light and power socket to the main loft (once we get a ladder/ access hatch in there), anyway, so will try to time this with that. Would it be possible to wire this to the the light circuit, or would it need to go the ring main?

Thanks again for the time you've put into this. The detailed answers have come in really handy.

Mikeyorks

jonny2510 wrote:

Any particulare reason for recomending the timed fans over humidistats?

Partly that I'm more experienced with the 'plain' fans that you can call in via a (light, normally) switch - but mainly that the humidistat doesn't work with odours / it's an extra sensor to go wrong?

So by my reconning, I need approx 130 cubic metres of air shifted per hour.

I under specced the one in my last house and always regretted it. If, as you say, you've got a real problem - I would go for the 250T. Doesn't use much extra power - but moves a lot more wet air.

do you have a link to this, as I can't seem to see it anywhere?

It's this I was thinking about :-

http://www.tlc-direct.co.uk/Products/BG4BS.html
- you just cut the flexible pipe at a suitable point - secure the cut ends over the inlet / outlet spigots on this with a wrap of tape. BUT - if the builder is going to fit a proper cowl over the soil pipe - don't bother with the back draft shutter as it should be unnecessary. I had to fit one with a West facing outlet, but you shouldn't need one, on reflection, with a vertical pipe and cowl.

I suppose if I'm doing it properly, alluminum would be the way to go. To avoid the mice thing if at all possible. I've never seen a mouse in the house, but I suppose it's better to be safe than sorry.

Use the aluminium anyway - as it's double skinned and therefore less prone to wear. It's just that I get dormice every winter - and new fascias etc have, surprisingly, not stopped them getting in.

the shower is in a cubicle. The fan vent is either going to go in the cubicle itself, or just outside it. I'm guessing in the cubicle would make it more effective.

Absolutely - put it central in the cubicle ceiling. The cubicle consolidates the steam - and this type of extractor will remove it without it getting into the rest of the room. You'll get some from a bath - and I find the extractor then works best if windows are not left open - but the door is at least ajar. Bit depends on the relationship with the person in the bath!! If, unusually, the cubicle is all the way up to ceiling - leave the cubicle door open when having a bath.

Unfortunately, it's gonna be real awkward to fit. The bathroom (on the second floor) sticks out from the rest of the house, and has it's own slanted roof. The loft void above the shower (where the fan would be located) does not appear to be accessible from the main loft, meaning the builder is proposing removing roof tiles, fitting a soil pipe (with cover), and then getting the electrician to wire (and maybe even fit) the in line fan himself.

That's a real issue you need to get your head round. You can't really entomb this sort of unit in a closed area that can only be accessed by taking tiles off. They are minimal maintenance (I take the motor out and wipe dust off the impeller blades every 4 months - takes 2 mins as the motor detaches the housing on spring clips) - but you do need to be able to get at them without a builder. If you can't generate access from the main loft - you really need, regrettably, to consider a hatch in the ceiling?

Am not quite sure what 3 core + earth is. I'll hopefully be getting an electrician in to add a light and power socket to the main loft (once we get a ladder/ access hatch in there), anyway, so will try to time this with that. Would it be possible to wire this to the the light circuit, or would it need to go the ring main?

It's the sort of cable you use normally for lights that have dual switches (eg top and bottom of stairs). But leave your electrician to worry as it really depends on where he can pick up the switched live to the existing light - and a permanent live which allows the fan to run on (set that at about 15 mins? The timer control is part of the fan electrics) after the light is off. The wiring instns with the fan - are pretty comprehensive. Yes - the fan is designed to wire into a light circuit - not the socket circuit. Try Midland Ladder Co for your loft ladder - they've a selection that fit most existing hatch sizes. But make sure you also check the hatch / floor distance as that's also a critical measurement.

Final bit. Do consider the ceiling vent with the light - if you have a cubicle. Makes a real difference to how it all looks - I found. But note that the Dichroic Halogen bulb that comes in this is fitted with 2 straight pins that gently pull straight out from the fitting. If, as me, you're used to the GU10 that twist - you can damage the fitting - as there's no instructions anywhere on this aspect. And don't forget you need the specific transformer with this? Another reason for needing access - as the transformer will likely go well before the fan needs attention.

All sounds a bit of a faff. But i've done it all and have a pristine bathroom with no mould - nor likely to be. Son came up from Uni over Christmas - and had a shower without the fan on, despite the prior instructions someone of his age ignore as a standard! The bathroom was absolutely awash - and with condensation dripping from the ceiling. So I comfort myself with the reminder that is how it would always be without investing just over £100 and a bit of work!

Best of luck with it all.

jonny2510

Thanks for this reply mike, only just come back to it and noticed it (didn't seem to get an email notification for some reason).

In looking into the job further I've decided rather than getting the builder in for a day, a "competent" friend who is a tiler is going to help me do the work. (As well as fitting a loft ladder into the main loft, and various other jobs). This also give the advantage of allowing me to learn to be a bit more handy around the house for future jobs of a similar nature,

To avoid disruption, I think we're now going to fit the extractor fan through the external wall, opposite the shower cubicle.

Whilst I realise this isn't as ideal as having it above the shower, it will make maintenance much easier, and bring down the cost of the job (which with the list of other things that need doing to the house is rising daily!)

Can you suggest a suitable fan to go directly into an external wall, as I'm guesing the inline fans will no longer be suitable?

Thanks again for all your advice in these two threads.

Jonathan