Two extractor fans into one duct

[cox377]

Hello guys,

I need to install an extractor fan into a new wet room, and one into the utility room next door. The 4" duct will go right over the utility room. Is it possible to use

To vent into a single exit point, or will one just blow into another?

Thanks

J

 

[securespark]

Don't think it will be efficient.

How long is duct run?

Is it flexi?

 

[ban-all-sheds]

Seek the advice of ventilation experts.

My non-expert imperfect understanding leads me to think that the upstream one could blow into the downstream one unless you have backdraught shutters (which reduce performance), and which the downstream one would struggle to open if the upstream one was running at the same time.

My feeling is that having 2 fans blowing into the same duct would be hard to get to work properly, and if I were to design it in the absence of advice from someone who is an expert I'd favour a single inline fan sucking air from both rooms.

Put in the biggest you can afford/will fit - grilles, ducting (particularly flexi or rigid with bends) and outlets sap performance, as do pressure differences.

These look pretty good: http://www.tlc-direct.co.uk/Main_Index/Ventilation_Index/Soler_TD_Silent/index.html

And don't run the ducting through an insulated unheated space without installing condensation traps. Best really, if it's running through the loft space, to insulate over the ducting and fan.

 

[ricicle]

I concur. The two fans into one duct with backdraught shutters is a non-starter (from experience)!

 

[securespark]

They are pretty good! That's what I have installed in my bathroom.

 

[cox377]

Hello Guys,

thank you for your responses.

The run from the wet room is about 2300mm from the hole in the ceiling to the exist point.

The run from the utility fan to exit is about 5mm as the fan will sit next to the wall.

What I was trying to avoid was two vents on the outside wall.

My thoughts were having the Y piece literally connecting straight to the wall so it only had about 400mm from the center of the Y to the outside. This would mean the merge of air would at the last possible point

 

[ban-all-sheds]

Ever had that experience with a basic mixer tap, or a basic non-thermostatic shower mixer, where if you turn on one supply full, then as you crank the other one up, you still don't get any of that one in the mix?

Or you've got a mix going, and then the tiniest adjustment of the tap(s) causes a massive change in the ratio of hot & cold coming out?

 

[SimonH2]

Or you've got a mix going, and then the tiniest adjustment of the tap(s) causes a massive change in the ratio of hot & cold coming out?

Oh yes, and of course everything designed so that you can't adjust the taps without being under the shower head The hotel management seemed to have passed the "how to not care less and show it" section of the course with flying colours.
I was tempted to report them, but had no idea who to - it was positively dangerous as the hot was very hot.

 

[cox377]

well two core holes in as well as the ducting. Now just to buy the fans

Thanks Guys

J