Two fans, one vent

Gavin83

Hi all. I’m currently renovating my ensuite and will look to do the main bathroom after. Currently neither of them have an extractor fan installed but I wish to put one in. Both rooms and next to each other and have empty loft eaves above them. I’m considering ceiling based extraction with the unit in the loft rather than putting it in wall.

My question is this. Is it possible to have both bathrooms venting via the same vent outlet? It would be easier to punch one hole through the wall/soffit/roof rather than two. Would this require one fan unit or two?

However I appreciate if there are issues with this it’s not really much more work to just create the second hole.

Thanks all.

koalakoala

We have just done this. It is possible but we were advised to have the two separate, which we did

fenwick458

create a second hole, it's much simpler. using 1 hole will end up costing more, I've done it (not my idea) and it did work but it cost more in materials and took longer to do than just making an extra hole. plus the sound carries right through from one bathroom to the other, you can hear people talking quite clearly.
I did also try 2 separate in line fans and a Y-piece venting out 1 hole a really long time ago, that never worked properly, air would get blown from one bathroom to the en-suite depending on the wind speed/pressure outside. also when both fans were on the extraction rate was still poor

ispookie666

I have the exact same setup, but contemplating changing it to MVHR. 
 
I put a Manrose 150T inline and two intakes(from each bathroom), via a Y junction and then venting out through one exhaust vent.  The fan is controlled by two timed PIR sensors (it can be activated by either).  Not the quietest system(but is a big fan!) .  All installed by myself after being badly let down multiple times by Electricians.  

Having two separate fans to single exhaust vent can be problematic unless you install one way flap valves.  Maybe easier to have another vent installed 

ashe

Make sure to consider condensation...

Ectophile

Unless you have valves in the pipes, then when one fan turns on, it will blow air out through the other fan, as well as through the vent.

Bendy_House

And I'd imagine that these in-line air flaps would be prone to sticking due to mix of steam and dust?

Another approach - tho' not without its own drawbacks - could be a single, powerfullish, in-line extractor, drawing from both rooms simultaneously, so would need to come on when either is used. Ie,  a Y-branch to join both ducts, with the fan fitted on the vent outlet side. This should actually 'work' in terms of successful extraction, but there would almost certainly be noise issues from excessively-running extraction, and possibly noise travel between rooms as mentioned by others.

One more potential solution - a bit of a bodge (so the sort of thing I'd try if needed...) would be to choose the most free-floating vent outlet, and then modify it with a central divider to take two ducts. The chosen in-line extractors would then need to be more powerful units to compensate for this additional restriction, but 'should' work. At least in theory.

I certainly would not use in-line flap valves, tho', as they are surely likely to stick over time, and will also leak to some degree, quite possibly enough to allow odours to backtrack to the other room.

Gavin83

Thanks all. So the general feedback seems to be that it's better to keep the extraction totally separate. In all honesty this was the answer I expected and given we need to create one hole it's not much more work to create a second, so I'll just take that route.

Chickereeeee

As my soffit was not suitable for drilling, I (had) installed roof tile-vents. They look like tiles, or slates or whatever your roof is covered with, but with vents incorporated. The flexible extractor ducting connects to the underside. They have worked very well for me, and there is no chance of damp air being sucked back in through the window trickle vents!

ashe

Chickereeeee said:

As my soffit was not suitable for drilling, I (had) installed roof tile-vents. They look like tiles, or slates or whatever your roof is covered with, but with vents incorporated. The flexible extractor ducting connects to the underside. They have worked very well for me, and there is no chance of damp air being sucked back in through the window trickle vents!

Out of interest, who did the work for you? I keep asking on local sites and seems like combination of electrician, plumber, builder, roofer etc which would cost a fortune? Did you do it yourself or get someone in? 

Chickereeeee

I had a local roofer pop the tile vents in (he was doing another job for me at the time, so just added it on).

I did the rest myself.

BTW, other comments imply you only need an in-line flap valve (non-return or backdraught valve) if sharing an outlet. You should have these fitted anyway, to prevent back draughts (imo).