Dips in ducts

[Mr Blobby]

I have read that dips in ducts can gather condensation. Is this only an issue for exhaust ducts carrying moist air?

 

To explain, we are running ductwork along the eaves in the warm loft but then changing direction 90 degress to run parallel to the ceiling joists to the MVHR manifold.

At some time in the future we would like to board the centre of the loft hence we would need to dip the ductwork into the void in the ceiling joists and then bring back up into the loft space the other side of the roof. Hence the dip in the duct under under the boarded area.

 

We only need to do this for two supply ducts so hopefully no condensation and no issue.

 

Also, is it ok to run the ducts on top of 400 centre joists or board the loft at the eaves first? Or am I overthinking it?

 

[Mike]

8 hours ago, Mr Blobby said:

Is this only an issue for exhaust ducts carrying moist air?

Yes, it's only the exhaust that's concerned.

 

9 hours ago, Mr Blobby said:

Also, is it ok to run the ducts on top of 400 centre joists or board the loft at the eaves first?

As long as the duct is adequately supported to at least the manufacturer's specified intervals, and well insulated, you're fine.