MVHR ducting planning

[Russell griffiths]

Just doing some planning before I get a company to do a proper design 

 

does every extract point have to have have its own dedicated duct, or can two or more extract points run back to one duct and  connect with a sort of Y junction. 

 

I have one area of ceiling that i that I would like to limit the amount of ducts in it, but this area then opens out into two separate rooms that would both have extract points in. 

 

[JFDIY]

Extracts usually have two ducts to cope with the flow and minimise noise. You might get away with three ducts onto two plenums , depend on the room use, size and expected flow rate

 

Could you run a larger duct past the obstruction then have a separate manifold to serve those two rooms?

 

 

[Dreadnaught]

I wonder if the concern about a y-junction connecting plenums for two rooms is the risk of cross noise transmission from room-to-room. And secondarily I wonder if it could make balancing the system more difficult if those two rooms were of markedly different size.

[Russell griffiths]

Oh so two pipes for an extract, ooh that’s a bummer, means I have to get more ducts in than I thought originally 

[Mr Punter]

It depends on the system design and duct size.