Upgraded bathroom extractor, still misting up problems

breakingbad

Hi all,

Newbuild (in 2014) house, main bathroom has no windows and mists up terribly when anyone has a shower, especially the large mirror.

The original fan was a horrible looking surface mounted Nuaire Genie, which according to their specs produced a rather weedy max flow of 25L/s. So I've upgraded the fan to an inline Manrose MF100T, which produces noticeably more airflow (max flow of 68L/s).

But the bathroom still mists up badly, even if the door is left open a crack.

Any suggestions? Would moving the fan grille to above the bath/shower help? What about using a 100mm Y-junction (which I have) and having the existing grille AND a 2nd above the bath/shower?

Any suggestions appreciated!

Thanks,

Gareth

coffeehound

Doubt that any amount of extraction will stop a mirror misting up. Heated mirrors might be money better spent.

ComicGeek

The air flow rates will be quoted assuming no resistance to discharge, which isn't realistic - the actual extract rate is likely to be significantly lower, once any ducting and grilles are taken into account. What type of ducting do you have, flexi ducting or rigid? Number of bends?

Might be better than what you had before, but might still not be sufficient.

Does the fan come on automatically with the bathroom lights? My preference is for fans with continuous trickle and boost function, so that it always extracts - amazing how much moisture is still left in the air once the fan switches off.

bob_a_builder

Heated mirror pads ...

https://www.tlc-direct.co.uk/Main_Index/Heating_Index/Mirror_Demister_Pad/index.html

ST1991

ComicGeek wrote: »

The air flow rates will be quoted assuming no resistance to discharge, which isn't realistic - the actual extract rate is likely to be significantly lower, once any ducting and grilles are taken into account. What type of ducting do you have, flexi ducting or rigid? Number of bends?

Might be better than what you had before, but might still not be sufficient.

Does the fan come on automatically with the bathroom lights? My preference is for fans with continuous trickle and boost function, so that it always extracts - amazing how much moisture is still left in the air once the fan switches off.

I agree with this.

In my old flat, my landlord installed a new extractor fan with moisture sensor. It came on with the bathroom light, and stayed on for a few moments after turning the light on - unless there was a certain amount of moisture in the air, then it would stay on (despite the light being off) until it was down to a certain level.
It had an adjustable sensor, so we could turn it up/down depending on how we got on, but right in the middle was perfect.

It worked a treat and the mirror would be mist-free in minutes. It also meant we didn't have to leave the door open allowing damp into the rest of the flat.
Our bathroom was in the middle of the flat, with no windows, and a half-wall mirror, which might sound similar to what you have.

breakingbad

Thanks for your replies.

I would love to put in heated mirror pads, but then mirror (6ft x4ft) is bonded to the wall (why, I'll never know!).

As for the fan, it vents out through a special roof tile, so there is about 4m of (relatively straight) insulated 100mm flexible ducting on the outlet side of the fan, and about 1m of the same on the inlet side, albeit with a few bends.

There is plenty of auction, it will easily hold an A4 sheet of paper up to the grille. I'm just wondering if moving the grille so it's above the bath would help.

Icecannon

as long as the mirror clears after a couple of minutes after a shower, sounds fine to me. No extractor is going to keep a bathroom clear of steam whilst the shower is on, in a smallish bathroom.

Jonesya

I'd ask how you're running it - are you switching it on while you're in the shower and then leaving it running for 10+ minutes once you've finished?

Also, what's the air-flow into the room like - is there a good gap under the door or trickle vents to let air in, or to you leave the door open?

andyhop

Change to a decent inline such as a XID100/150. You will have zero issues if you use the correct fan

Extraction will be 4 fold current

Use solid pipe too for the bst result

Geoff1963

Condensation occurs, on something which is colder than the dew-point of the air. Is the mirror bonded to the wall or could you move it away a centimetre or two ? If it is wicking heat away to a cold outside wall, it will always be colder than the bathroom.

breakingbad

andyhop - the xid100 would produce 4x the flow of the MF100T? The peak flow specs are only 288m3/hr vs 245m3/hr. I chose the man rose inline can because if it's high flow rate and excellent reviews - flow is 4x that of the Nuaire Genie one I replaced. Would the did-00 be that different?

the fan comes on automatically with the bathroom light (so any time anyone enters the room, as no window).

Mirror is bonded to an internal stud wall, so shouldn't be wicking that much heat away. No chance of removing it from the wall without breaking it.