duct for extractor fan

[swilli88]

Not sure this is the right place for it but thought id try

Installing a pvc rigid duct for an extractor fan and it has to manourver through a small enough void between a support wall and subfloor.

Rather than getting some fittings to try and maneuver it through with 90 degrees or 45 degrees or a combo of both...has any ever used a heat gun to locally heat a length of duct run to allow it to be slightly deformed without burning a hole through it obviously.

It would allow for a much smoother duct run and less static pressure im thinking

Thoughts?

 

[johnny2007]

Tried it many times.
Ended up using a flexible duct, much easier and once installed correctly it will be no different from the rigid one.

 

[swilli88]

I see thanks.

My duct run is about 4.5m and i have extremely limited space to put the fan in the understairs WC so was trying to reduce static pressure as much as possible

I dont have room for any centrifugal fan I could find and an in-line fan would mean i would need to cut an access panel into the spare room laminate and subfloor to have access....

 

[^woody^]

Nice idea, but I suspect that even if you could heat and bend the pipe (I've tried too and with limited success) the pipe ends up deformed and not smooth internally, so it defeats the whole point of tying to get a smooth flow.

Use a flexible duct which can be deformed to different shapes not just angles.

You can get centrifugal fans which are surface mounted, it does not need to be in-line.

 

[swilli88]

hi woody. yes that makes sense. My issue with the surface mounted centrifugal fans is that they are huuuge compared to axial and this room is so tiny that it would look mental!

i found a couple that might do the trick

blauberg calm 125
airflow icon30

they are both mixed flow impellor fans with higher pressures than axial but still quite slim and neat (some dodgy reviews on amazon for the airflow 30 though with the gimmicky backdraft aris so im leaning towards blauberg)

 

[swilli88]

whats the best wat to connect pvc ducting? duct tape? solvent weld?

 

[johnny2007]

whats the best wat to connect pvc ducting? duct tape? solvent weld?

They just push fit.
Put a small screw if you want to secure the joints.
Stainless steel self tapping would be my choice