Opinions on this extractor ducting setup please

[tataylor1]

Hi all.

I recently replumbed the pipework to the bathroom shower and then boarded the loft floor. It was then that I decided to replace the old extractor fan with a same but newer model and I replaced the plastic flexi hose with an aluminium one and some rigid 100mm piping at entry and exit.
The previous hose snaked flat along the loft floor and was constantly full of water so I tried to give an upwards elevation to the fan (drawing rising steam) and a downwards slope to the exit (running condensate and preventing any blown in rain from gathering in the pipe).
Is this a decent enough theory? Or should I remove this pipe, fill in the existing exit hole and drill a new exit hole much closer to the fan?
Is it worth it for the extra effort? I will have to buy a 100mm hole saw.
I've read on here how little people think of flexi-ducting but working with the existing exit hole and the soil pipe it was the most sensible option for that weekend.

Thanks for any help! There's a digital pint in it for you.

Untitled

• tataylor1
• 5 Apr 2013
• 1

 

[OwainDIYer]

Avoid the flexi duct as much as possible.

Go straight up from the fan only as much as needed to give a gentle fall on the next straight pipe which goes to inside the exit hole. Then a bend to go out through the hole.

Insulating the duct can avoid steam condensing.

 

[tataylor1]

i didnt really want to use flexi but i wanted to finish up the loft work so i thought a plastic to aluminium upgrade would help.

i appreciate its a long length tho....

perhaps il insulate the section of tubing before the fan (so the steam stays as steam and is drawn through) and I wont insulate the part of the ducting after the fan, so that if it condenses anywhere, its there, and this can trickle out of the vent along with the steam.

ta!

 

[JohnD]

wrap all of the duct in insulation to keep it warm. You get condensation because it is cold.

Make sure the timer runs it on after use

Use rigid pipe, sloping to the outside as much as possible.