Bathroom inline extractor fan

[dazzler9000]

Hello,

I'm struggling with condensation/black mould in the bathroom above the bath. I currently have a Manrose MF100T 4 Inch fan with a single extraction point above the shower.

I'm planning to upgrade to the 6inch version but use a Y piece, so I can split the ducting to extract above the shower and the bath.

I appreciate that flow will be reduced but is there any other reason not to do this?

 

[dazzler9000]

Anyone have any real-world experience here and can offer any advice?

 

[foxhole]

Did that in my old shower room , two extract points worked well with powerful fan .

 

[dazzler9000]

Thanks, Foxhole. I'm hoping the 6" fan is up to the job.

 

[Mr.B]

Must admit I'm heavily into extraction.

My cooker hood is a 15 year old six inch Britannia and ducted with solid tubular ducting and is fabulous - so I understand why you might lean towards 6" in the bathroom.

But, in my bathroom and shower rooms I didn't go as far as having 6" fans, instead I went for powerful 4". I think you'd improve things by getting something like this:- Soler & Palau SL TD250T In Line Fan Kit https://www.tlc-direct.co.uk/Products/SLTDK250T.html .... it's pretty powerful.

If your present ducting is corrugated/flexible then, as you well know, you would improve the flow by going for solid tube.

Certainly if you had two of those mentioned above, and ducted independantly then you'd be OK but even if they were joined via Y piece I'd think you'd be a lot better off than what you have at present.

 

[dazzler9000]

Must admit I'm heavily into extraction.

My cooker hood is a 15 year old six inch Britannia and ducted with solid tubular ducting and is fabulous - so I understand why you might lean towards 6" in the bathroom.

But, in my bathroom and shower rooms I didn't go as far as having 6" fans, instead I went for powerful 4". I think you'd improve things by getting something like this:- Soler & Palau SL TD250T In Line Fan Kit https://www.tlc-direct.co.uk/Products/SLTDK250T.html .... it's pretty powerful.

If your present ducting is corrugated/flexible then, as you well know, you would improve the flow by going for solid tube.

Certainly if you had two of those mentioned above, and ducted independantly then you'd be OK but even if they were joined via Y piece I'd think you'd be a lot better off than what you have at present.

Hi Mr B, I have to admit to not doing a huge amount of research on the subject of flexible and solid tube. Is it a well-known fact that solid if far superior? I'm thinking a solid 6 inch tube could be tricky to manage in a loft space and then there's the mention of insulating it although, I'm not sure how necessary that is.

I also see there is a semi-rigid option, anyone used this?

 

[Mr.B]

If you recall I suggested sticking with good quality, powerful four inch fans (with over-run timers on each) - one over the bath and one over the shower and using solid tube with a four inch Y connector. All of which are readily available (including the Y connector https://www.screwfix.com/p/manrose-circular-y-piece-connector-white-100mm/23574 )

The six inch would be considerably more unwieldy (and more expensive). In the loft you only need to drape ordinary loft insulation over the tube (I did that myself too).

If you have to change direction then you could use short lengths of aluminium flexible ducting, but use as much solid tube as possible to reduce resistance.

Yes, I did use six inch for my kitchen cooker hood but I was able to take it into my garage and then out through a wall to outside but I wouldn't use six inch in your situation.

 

[dazzler9000]

If you recall I suggested sticking with good quality, powerful four inch fans (with over-run timers on each) - one over the bath and one over the shower and using solid tube with a four inch Y connector. All of which are readily available (including the Y connector https://www.screwfix.com/p/manrose-circular-y-piece-connector-white-100mm/23574 )

The six inch would be considerably more unwieldy (and more expensive). In the loft you only need to drape ordinary loft insulation over the tube (I did that myself too).

If you have to change direction then you could use short lengths of aluminium flexible ducting, but use as much solid tube as possible to reduce resistance.

Yes, I did use six inch for my kitchen cooker hood but I was able to take it into my garage and then out through a wall to outside but I wouldn't use six inch in your situation.

I currently have the 4 inch version 'Manrose mf100t' in this bathroom and its doesn't vent to room enough, so I'm convinced I need a 6 inch version especially as I want to split the extraction points. I'm also not keen on getting an electrician in to do the necessary wiring to run 2 x 4 inch fans.

I will explore the 6inch varieties and see how I get on. Mr B, did you install a condensation trap in your configuration or are these not really needed if you position the fan higher than the ducting i,e. there is a runoff to the external outlet/vent.

 

[JohnD]

The Manrose mf100t is reasonably powerful. Perhaps there is some other reason it is unsatisfactory

Show us some pics of the ducting and vents

How often do you run the fan, and for how long?

How long is the duct? Is it straight?

How is the room heated and ventilated?

What size is the room?

How many showers do you have a day, and how long?

 

[Mr.B]

I currently have the 4 inch version 'Manrose mf100t' in this bathroom and its doesn't vent to room enough, so I'm convinced I need a 6 inch version especially as I want to split the extraction points. I'm also not keen on getting an electrician in to do the necessary wiring to run 2 x 4 inch fans.

I will explore the 6inch varieties and see how I get on. Mr B, did you install a condensation trap in your configuration or are these not really needed if you position the fan higher than the ducting i,e. there is a runoff to the external outlet/vent.

No condensation trap fitted.

 

[dazzler9000]

The Manrose mf100t is reasonably powerful. Perhaps there is some other reason it is unsatisfactory

Show us some pics of the ducting and vents

How often do you run the fan, and for how long?

How long is the duct? Is it straight?

How is the room heated and ventilated?

What size is the room?

How many showers do you have a day, and how long?

Hi John,

I'd set the fan to run for about 20mins (let's not talk about how infuriating it is to set the timer on these Manrose units).

The room is about 3metres square, so guess the ducting was about 4 metres in total and straight. As it happens, since creating this thread, I've had to troubleshoot an extractor fan issue in another bathroom, so I borrowed this MF100T to feed that bathroom. Consequently, I don't actually have a fan in the room we're discussing. I was contemplating an upgrade anyway, so now seems like a perfect time to upgrade especially as I'm adding another extraction point.

Probably a couple of showers a day or a bath. The walls are literally dripping from moisture when it's used. The wife won't have the window open in the winter whilst using the bathroom, so I'm fighting a losing battle. I vent the room for about 30mins afterwards and this seems to clear it.

The room has a 6ft towel radiator. It never gets massively hot, so I was planning on swapping it out for one of these at some point https://www.bigbathroomshop.co.uk/m...er-radiator-1780mm-x-560mm-double-panel-79394 as this should help.

 

[Mr.B]

I moved into my first house in 1974 and fitted, what was called in tbose days, a Dimplex Heat and Light fitting. It was just a wall mounted fan heater with a light bulb incorporated.

You can't get them any more but you can still get wall mounted fan heaters designed for bathrooms. And ever since 1974 I've had one in the bathroom. You set them to either one or two kilowatt and they do keep the bathroom remarkably clear of steam and they make the room lovely and toasty when you get out of the shower.

Ideally you'd connect it to your ring main via a fused spur at a height stipulated by the manufacturer and it's operated by pull cord.

 

[JohnD]

Probably a couple of showers a day or a bath. The walls are literally dripping from moisture when it's used.

Sounds like the walls are cold. Are they uninsulated external walls? Are the internal walls, and the insulated ceiling, fairly dry? my own bathroom got noticably free of condensation when I had CWI installed.

I'd suggest turning the fan on before you start the shower, and leave it turned on (not just on the timer) and check back from time to time to see how long it takes. Leave the door and window shut so that the fan can create suction and there is little air movement. Water vapour is lighter than air (hence clouds) so will naturally rise towards the ceiling, where the fan will take it. Unless abnormally tight, the gap under the bathroom door will allow fresh air to enter and to stratify under the warm, steamy air. If you think the gap is very tight, leave the door open by no more than the thickness of a pencil.

Wet towels will contribute to the water in the room.

BTW towel rails give out far less heat than radiators, especially when they are wrapped in a thick insulating layer of towels.

Tall radiators send the heat up to the ceiling. A low, wide one will heat the room better. You can put towel rings or a rack on the wall above it as they will not obstruct heat escaping.

 

[dazzler9000]

Sounds like the walls are cold. Are they uninsulated external walls? Are the internal walls, and the insulated ceiling, fairly dry? my own bathroom got noticably free of condensation when I had CWI installed.

I'd suggest turning the fan on before you start the shower, and leave it turned on (not just on the timer) and check back from time to time to see how long it takes. Leave the door and window shut so that the fan can create suction and there is little air movement. Water vapour is lighter than air (hence clouds) so will naturally rise towards the ceiling, where the fan will take it. Unless abnormally tight, the gap under the bathroom door will allow fresh air to enter and to stratify under the warm, steamy air. If you think the gap is very tight, leave the door open by no more than the thickness of a pencil.

Wet towels will contribute to the water in the room.

BTW towel rails give out far less heat than radiators, especially when they are wrapped in a thick insulating layer of towels.

Tall radiators send the heat up to the ceiling. A low, wide one will heat the room better. You can put towel rings or a rack on the wall above it as they will not obstruct heat escaping.

Some great advice here from everyone, many thanks.

Yes, I think you're probably right. The walls in question are standard cavity wall build. The ensuite is above the garage and I'm guessing is about 10/12 years old. I don't know if it's had cavity wall insulation or whether it would be insulated from the build (don't know what the regs were/are). As I mentioned the current radiator doesn't get very hot for some reason (just looking into balancing the system) but I will look to replace with the one linked to above. Probably another thread but my current towel rail pipes come through the floor. I notice that these normally accept pipe from within the walls. Presumably, it's possible to fix one of these https://www.bigbathroomshop.co.uk/m...er-radiator-1780mm-x-560mm-double-panel-79394 and just use the correct valve?

 

[dazzler9000]

So, I'm now considering a single 4-inch fan with dual extraction points with solid piping. I just think it'll be easier to work with. I get the vibe that everyone thinks 6inch is a bit overkill.

Question about the solid piping. Presumably, any bends or joins should be welded via solvent cement?

Is this the right move everyone