Bathroom misting up ventilation issue

seeker68 · 9 Feb 2015

I've got a bathroom 7' x 5'5", with one window. It was taking a long while to demist the mirror, like 20 minutes so I replaced the fan with an Envirovent 100. It didn't make any difference.

I then went to the outside end of the vent removed it and found ducting was part broken at the end so I taped it up and Made sure it didn't leak. Still it didn't make any difference. Is there something else I can do or is this fan no good?

RF Lighting · 9 Feb 2015

Get a mirror demister.

https://www.tlc-direct.co.uk/Main_I...r_Demister_Pad/index.html#Mirror_Demister_Pad

delmel · 9 Feb 2015

envirovent (not sure who actually makes that brand) but probably not the best of quality.

Is the ducting a straight run without bends ?
Also how long is the ducting to the outside?

Centrifugal fans will certainly operate over longer distances, but a decent brand usually also helps.
You could also try the quiet ones that run on trickle

Also be mindful, you cant just suck air out, you need air input also so leave the bathroom door open while fan is running on (after you leave obviously)

EFLImpudence · 9 Feb 2015

Is twenty minutes a long time?

ericmark · 9 Feb 2015

Where is the air replaced from? With some thing like this

air is replaced with air from outside which in winter will have a very low dew point. But any air taken from rest of house could have a much higher dew point so far more air needs replacing.

Simply mounting the mirror with a slight gap from wall so wall does not cool it can help.

My office at moment at 22.6°C and Humidity of 33% has a dew point of 9.2°C but outside at 4.7°C and Humidity of 95% has a dew point of 3.7°C so less air needs to be replaced from outside than from my office to dry a bathroom. Often the dew point has a far greater gap 3rd Jan 9.4 - 0.2 and my house is rather dry.

My wife will comment "We have a heck of a draft from that front door" but switch off the tumble drier and the draft stops. Simple law of Physics to pump air out of a room it has to be replaced from some where.

We all do it we go to great lengths to stop drafts then wonder why mould is growing in bathroom. Open bathroom window with fan on and very quickly the moisture goes. However bathroom also becomes cold.

seeker68 · 9 Feb 2015

delmel said:
envirovent (not sure who actually makes that brand) but probably not the best of quality.

Is the ducting a straight run without bends ?
Also how long is the ducting to the outside?

Centrifugal fans will certainly operate over longer distances, but a decent brand usually also helps.
You could also try the quiet ones that run on trickle

Also be mindful, you cant just suck air out, you need air input also so leave the bathroom door open while fan is running on (after you leave obviously)

Hi, it's an Enviro Vent silent 100 - lower or middle of the range I believe.
Ducting is about a metre long with slight bend.

I wonder if it's wired/set up wrong it's blowing instead of sucking..?

seeker68 · 9 Feb 2015

ericmark said:
Where is the air replaced from? With some thing like this

air is replaced with air from outside which in winter will have a very low dew point. But any air taken from rest of house could have a much higher dew point so far more air needs replacing.

Simply mounting the mirror with a slight gap from wall so wall does not cool it can help.

My office at moment at 22.6°C and Humidity of 33% has a dew point of 9.2°C but outside at 4.7°C and Humidity of 95% has a dew point of 3.7°C so less air needs to be replaced from outside than from my office to dry a bathroom. Often the dew point has a far greater gap 3rd Jan 9.4 - 0.2 and my house is rather dry.

My wife will comment "We have a heck of a draft from that front door" but switch off the tumble drier and the draft stops. Simple law of Physics to pump air out of a room it has to be replaced from some where.

We all do it we go to great lengths to stop drafts then wonder why mould is growing in bathroom. Open bathroom window with fan on and very quickly the moisture goes. However bathroom also becomes cold.

Air from open garden..

Taylortwocities · 9 Feb 2015

seeker68 said:
I wonder if it's wired/set up wrong it's blowing instead of sucking..?

easy to test. put a piece of (unused!) loo paper over the fan when it is running. If the paper sticks to the fan then it is sucking.

Many of the lower priced axial fans are barely able to pump air though a short wall duct.

Also, the route that air takes from entering the room (at the door??) and leaving the room through the fan will make a difference.

I assume its a timer fan.?

ericmark · 9 Feb 2015

The

shown is a heat recovery unit not just a simple fan. It heats up air coming in from the air going out so theroy is no cold drafts and much drier air than is air came from rest of house.

Seen advertised but not seen in use. The fan only blows air one way and it relies on a reasonable seal on the door to rest of house to push air in both directions. Clearly this will change house to house.

I have seen where fans do bring in cold air rather than suck out cold air but in the main the incoming air is aimed at a heating appliance with an open flue. The basic idea is blowing air in will not cause a depression in the house and suck flue gasses into the room.

In theroy in my house we should not use a vented tumble drier but since we only use the gas fire when central heating fails and we know both tumble drier and gas fire should not be run at the same time there is not really a problem.

In my house any bathroom extractor would have to be the heat recovery type. The first heat recovery units had a huge box as a heat exchanger but the latter types the heat exchanger is part of the extractor pipe. Out air is warm so goes up and in air is drawn from bottom.

As to what happens in the summer is another question.

delmel · 9 Feb 2015

heat recovery units (nice and expensive) could be the answer but I wouldn't necessarily go down that route.

20 min is not that long, but some of the fans out there now are simply crap. Try to stick to a decent branded one.

Vent Axia
Aidelle
Greenwood Airvac
Xpelair
Silavent

Probably in that order, but even in those names they have cheap crappy ones.

seeker68 · 9 Feb 2015

delmel said:
heat recovery units (nice and expensive) could be the answer but I wouldn't necessarily go down that route.

20 min is not that long, but some of the fans out there now are simply crap. Try to stick to a decent branded one.

Vent Axia
Aidelle
Greenwood Airvac
Xpelair
Silavent

Probably in that order, but even in those names they have cheap crappy ones.

Okay thanks Delmel. I think I paid about +/- £25
20 minutes is quite a long time if you're waiting for the bathroom mirror to de-mist so I can see what I'm shaving..

seeker68 · 10 Feb 2015

Thanks everyone, all useful information.

EFLImpudence · 10 Feb 2015

seeker68 said:
20 minutes is quite a long time if you're waiting for the bathroom mirror to de-mist so I can see what I'm shaving..

It is but the bathroom WILL mist up. There is NOTHING you can do to stop that.

You could shave before your bath or -

stop being effeminate.

Taylortwocities · 10 Feb 2015

or

RF Lighting said:
Get a mirror demister.

https://www.tlc-direct.co.uk/Main_I...er_Pad/index.html#Mirror_Demister_Pad[/QUOTE]

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Bathroom misting up ventilation issue

Similar threads