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Extractor Fan

a l e x

Distinguished Member
Afternoon all, calling on the GC knowledge re fans...!

Just had a new extractor fitted in our bathroom as the old one was crap. Was hoping this would solve the problem but the bathroom is still full of steam which won't shift until the window is wide open. I don't think the fan is very powerful but I think the venting is probably half to blame too. Looking in the loft the fan is vented through the circular tumble dryer style pipes. The other bathroom also has an extractor so they both seem to go into a t shape piece which then goes to the vent to outside on the wall. There's loads of piping though, probably a good 5m between the fan and the outside vent. I doubt it going into some sort of connector is helping either.

I don't really want to cut a hole in the roof to fit another vent, is there any other way to vent it? If not, I assume I'm going to need something pretty powerful to make it shift through so much piping? Planning on going up with a load of tape to make sure the pipes are all sealed to the connector etc but can't see it helping too much. The bathroom ceiling has cracked a fair bit I reckon is down the the moisture so hoping to get this sorted...

Thanks!
 
D

Deleted member 293381

Guest
Note that an extractor fan needs to move air out of the room. If there is no way for air to get into the room to replace the air extracted then the fan will not work. Air in = air out.

In addition, when a fan starts up it needs to physically move the still cold air in the loft pipe - push it to the outside vent. That will take some energy to shift it along a five metre pipe.

Recommend checking the outside vent - might be partially blocked with stuff trapped in old spiders cobwebs.

Also temporarily disconnect the pipe from the T-shape junction and check there is a flow of air out of the pipe at that point. If there is a flow then the problem lies somewhere from the junction to the outside vent.

Good luck!
 

niceguy235uk

Prominent Member
Regardless of how much air is in the pipe, a standard 4" extractor fan is just not suitable, especially over that distance AND using flexible ducting.
 

a l e x

Distinguished Member
Thanks all. Going to get some new ducting and run it direct to the outside vent. We don't use the main bathroom for showers etc, only the en suite so no need for both to be ducted at this moment. Will also look at getting an inline extractor fitted. Thanks again!
 

davepuma

Distinguished Member
Sorry to hijack the thread but I have a similar query!

I've just had the bathroom done (finished apart from a couple of snags) and the new fan on the outside wall is struggling to shift the steam caused by the new 'rainshower' shower head. I have adjusted the fan to its maximum setting but the walls and ceiling are still dripping with water after a shower. There isn't a gap under the bathroom door for air to get in, which I plan to rectify but having tried showering with the door slightly ajar and the window open and towel rail on full blast, that doesn't appear to be the issue so I think I'm going to have to install a second fan in the loft. The distance from the shower to the wall is roughly 2.5m. Would a 4" fan like this cope or would I be better off getting a 5" version bearing in mind that I will still have the existing wall fan in situ until I decide whether to get rid of it but that would mean filling the hole etc. and I've only just had the bathroom done so everything is shiny and new! I have a concern that the two fans running will clear the steam but will cause the bathroom to get cold by removing all the warmth! This is the fan that was fitted by the plumber: Link
 

majnu

Distinguished Member
use a coloured smoke bomb to see if the extractor is working properly or if there are any leaks in the duct work that lay in the loft. I got one of these fitted when we had our loft conversion done.



I picked mine up from ebay for around £40 new on ebay. I think they are 6" but they shift a lot of volume of air at relatively low noise.
 

IronGiant

Moderator
@davepuma I think any fan will struggle to shift steam as it is produced, unless it's the size of a cooker hood. They are there to shift the damp air, after the event and may take several hours to do so.
 
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Deleted member 293381

Guest
@davepuma - IG is right.

A rainshower head, when having a nice hot shower, will produce a large amount of steam which an extractor fan cannot handle.

Best thing to do is have your shower and when finished open the bathroom window wide (if you can find it in the steam :)) and close the door and leave it for an hour or two, let nature take its course. Even in winter the bathroom will dry out.
 

Wahreo

Distinguished Member
The thing I have noticed over the years with power showers is that even with a standard handset or rain shower, the water coming out of these stirs up the air in the entire room so everything gets covered in moisture. Even with a decent centrifugal fan or mixed flow fan, it will struggle to clear the room fully.

Best thing to stop the mirrors steaming up is a demister on the back of the mirror.
 

DOBLY

Prominent Member
Also, the room layout and position of the extractor and window will make a difference. If the steam is extracted from near to the source (eg shower), the build-up in the rest of the room will be less.
We have the fan running from when the shower is on until the user has left the room - at that point the window is opened and the door shut - no problems with mould, odours etc. So many houses have either smelly, mouldy bathrooms, or their whole house is cold and damp because they don't know how to locally ventilate a bathroom..... it's hardly rocket science!
 

DOBLY

Prominent Member
Best thing to stop the mirrors steaming up is a demister on the back of the mirror.

Best thing since sliced bread, imho. Ours is linked to the lights around the mirror. Works so well, and is such a cheap thing to install when re-doing a bathroom.
 

davepuma

Distinguished Member
Best thing since sliced bread, imho. Ours is linked to the lights around the mirror. Works so well, and is such a cheap thing to install when re-doing a bathroom.

Have a demisting mirror and agree it's fantastic.
Also, the room layout and position of the extractor and window will make a difference. If the steam is extracted from near to the source (eg shower), the build-up in the rest of the room will be less.
We have the fan running from when the shower is on until the user has left the room - at that point the window is opened and the door shut - no problems with mould, odours etc. So many houses have either smelly, mouldy bathrooms, or their whole house is cold and damp because they don't know how to locally ventilate a bathroom..... it's hardly rocket science!

The all-in-one bathroom places suggested in-line fan ducted out of soffit or roof but independent plumbers said existing wall fan arrangement would suffice. I guess they just want the job to be as easy as possible. I went with the plumber's advice, something I'm beginning to regret!
 

majnu

Distinguished Member
any reason why you deleted my post?
 

IronGiant

Moderator
Yes, it got posted it twice. I deleted the second one. The first one seems to have gone AWOL (glitch in the software?) so I'll re-instate it. Sorry about that.
 

NewfieDrool

Banned
Many years back I worked for a well known company that manufactured extraction fans and we did a range of fans for bathroom use.
We had lots of queries on this and the response was to leave a window open to allow airflow.
Modern houses are well sealed and so the air in simple terms can't be moved as effective as it would if air was to be allowed into the property/room.
If you have a timer setting its best to let it run on after the lights go out for a least 15mins. Not only does this shift more air from the room it cuts down on the condensation within the pipe work. We had a good number of fans were the pcb would be burnt out due to water dripping back or collecting on the pcb.
They need to be cleaned regularly as dust build up on the impeller creates a poor performance and also shortens the life of the motor.
We had several customers who had installed inline fans from our range of commercial fans, these worked well where possible.
Most of the dedicated bathroom fans were low powered and to be honest pretty damn poor.
 
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Wahreo

Distinguished Member
I agree with that, the little all in one shower kits are rubbish.

Also, take ½" off the bottom of the door, that'll help.
 

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