Boxing in an inline centrifugal fan in bathroom

[charlie30]

Hi all, I currently have a standard bathroom wall fan that does not clear water vapour quick enough from hot power showers. It has a 4 inch duct straight through the wall.

I looking to upgrde the wall fan to something like this:

http://www.tradeelectrical.com/manrose-mf100t-100mm-inline-timer-fan-p-881.html

My plan is to remove the existing fan, and put in its place the new inline fan, and run a 90degree bend to the existing duct. I would then box the unit it, with a standard grill over the air intake. This would allow it to be accesible in future, but hidden away.

Would appreciate if anyone has done this before? Anything issues to look out for? Unfortunately we don;t have a loft where these sort of fans are normally placed (it's a flat).

But I've heard good things about these fans, I don;t think there are any standard wall fans that do as good a job?

Cheers

Charlie

 

[stem]

You can get centrifugal fans that mount in the wall, they have the same operating principle as your inline fan, but would look neater. Click here for an example. Centrifugal fans usually are used where there are long duct runs to overcome the pressure loss caused by the resistance of the duct. Other sizes are available.

 

[viewer]

You need to measure the bathroom to get the volume and then multiply by 8 to get the flow per hour and then look for the fan. That fan, with no restrictions in the pipework would only do about 80 cubic metre room, so it may well be too small for the task anyway. Biggest problem with trunking/panelling is condensation either inside the pipe from the fan or on the outside between the pipe and the surrounding boxing.

 

[JohnD]

the Manrose is nominally 245m3/hr so is about three times as powerful as most on-the-wall extractors. I see taps4less don't disclose the extraction rates of their fans, which makes it difficult to see a suitable one.

If you can find a small neat one as powerful, let us know. The in-lines are usually mounted in the loft above the bathroom, on a firm platform that will help muffle the noise.

 

[Lectrician]

And if going for a larger extract rate, make sure air can get into the room too - a door that doesn't rub the floor is fine (gap under). If you seal the room, the fan is pulling on a vacume, and won't extract anywhere near it's spec.

 

[securespark]

You can buy insulated ducting but it is extremely bulky.

http://www.tlc-direct.co.uk/Main_Index/Ventilation_Index/Accoustic_Ducting/index.html

 

[charlie30]

Cheers for the responses everyone.

I am sure the original design of the building did not try to accomodate power showers, so ventilation is something we're considering now that we do have a power showers. We have plenty of room under the door to prevent a vacuum, a gap of 2cm x 69cm.

I have calculated the extraction rate required using tlc-direct.co.uk's fan calculator, and require a performance of 259m3 per hour. This is based on the 'Bathroom with Shower' setting, and a room that is 2m x 3m x 2.4m in dimensions.

The link to the fan calculator is here:
http://www.tlc-direct.co.uk/Technical/Ventilation/Ventilation4.html

I think my options now are:

1. Use a wall mounted centrifugal fan as per one of the postings on here. This will be easiest as it's like for like, replacement our existing fan.
Problem with this is that I cannot find any powerful ones.

2. Box in an in-line centrifugal fan.
Problem with this is that it will be a little un-sightly.
Has anyone done this before?

Either way I will let you know how I get on, and if it helps clear the mist we get from my misses' hot power showers.

 

[JohnD]

pity you haven't got a loft.

 

[Aragorn84]

the TLC calculator recommends quite a few different fans that would suit, albeit 6" ones...?

 

[Lectrician]

National Ventilation do a Diverso Centrifugal which fits a 100mm hole, and extracts 240 or 250m3/hr. They also do an uglier looking Monsoon Compact 300 with the same-ish spec. The Diverso can also be flush mounted.

 

[charlie30]

I think the National Ventilation fan might be just the thing. The most powerful version will still fit my existing 4 inch duct, yet achieves 240m3/h.
A little noisy though at 47 decibels!

I don't fancy enlarging the duct to 6", so fingers crossed I can get hold of the one of these fans.

Ouch... just checked the list price at http://www.natventshop.co.uk, 125 inc VAT.

 

[Lectrician]

Go via a wholesaler.

 

[charlie30]

Just an update, I got the Vent Axia Lo Carbon Quadra in the end because I was able to get this off fleabay quite cheaply. It is a wall mounted centrifugal fan, smart appearance but obviously a little on the noisy side.

I have a hot power shower set up (over a bath tub), so my problem was a lot of water vapour in the air during and after showering, my old fan just wasn't up to the job. But with this new fan on full blast, we can have hot showers that are not steamy. This thing has serious power

Surface water evapouration is then taken care of with the fan's trickle mode which is almost silent.