Fan Install

[Marvo]

7.5 cubes is about right, the ducting i was going to use was 100mm and flat chanel 110 x 54.

Your question about the rules I'm afraid I don't know. What I do know is that your codes are designated Part A-P (Part P being the real crowd pleaser) and one of them should specify minimum requirements for bathroom forced ventilation.

Your ducting sounds undersized, with the lengths you were talking about I would suggest at least a 150mm solid round duct and a flat channel with at least around double the crossectional area of the 110x54. All ducting bends and reducers as well as discharge grills and attenuators etc add significantly to the fan requirements

I would seek assistance with this project if I were you. You need someone to draw the system in a CAD or fan-select package and come up with a predicted system static pressure.

 

[soulman]

I must add i purchased a new build in 2007 & the fan run on one of the bathrooms is approx 4 metres with a £10.00 fan sucking the air out.

 

[Marvo]

....the only litres per second of the fan exceeded 20L p/s which the majority of fans do.

The delivery volume of most domestic fans is given as a free-air figure. This figure is meaningless with the ducting arrangement you're describing.

 

[Manator]

It is easy to do, just do the calculations for the required air changes for the requirements, allow the appropriate mixing factor and you will have the fan flow required.

No different to an other design work, you just need to be competent.

That expensive course paid off then

For those who do not know Sidewinder is qualified to test airflow in working environments, and is fully aware of the regulations.

In the home or domestic environment perhaps the law may not be as harsh, but the principles should be the same.

 

[soulman]

Hi just to conclude this thread, I installed 2 metres of 204 x 60 ducting connected to a mixed flow inline fan then a further 4 metres of 4 inch rigid pipe. The fan was more than suitable even with this long run. In the future i will install inline mixed flow fans as standard the power was very impressive. Building control were happy with the install, and i thought this was unusual, he asked me to turn the timer over run down to a couple of minutes instead of the twenty i had it set to. Thanks to the chaps who gave constructive advice.

Cheers

 

[Marvo]

Thanks for the follow-up, glad the system you installed was performing well. I agree mixed flow fans are a good option where there's a decent run of ducting, they handle the pressure better than axial fans plus they're nice and quiet when they're running on-curve. They're well worth any extra cost.

 

[steptoe]

what fan did you actually fit in the end?

 

[soulman]

Hi Steps it was the Manrose 100 timer model. 245m3/hr. There was a lower setting on the fan, i think abour 180m3/hr. I read that building control now required fans with a timer to over-run, but the guy from building control said it was not necessary and could be annoying to the householder, even though it could be switched off at the isolator. I also read the manrose catalogue which gives useful info on air changes etc.

Cheers

 

[steptoe]

Hi Steps it was the Manrose 100 timer model. 245m3/hr. There was a lower setting on the fan, i think abour 180m3/hr. I read that building control now required fans with a timer to over-run, but the guy from building control said it was not necessary and could be annoying to the householder, even though it could be switched off at the isolator. I also read the manrose catalogue which gives useful info on air changes etc.

Cheers

cheers soulman, its good to know just how problems have been sorted so that further similar issues can be pointed to the thread/solution.