Another backdraft shutter question

Our tumble dryer vent goes from the machine via a snort length of round flexi ducting to the round to rectangular converter, though 90 degrees, up the wall to the ceiling then out though the wall to a grille. In the rectangular outlet section is a flap (that from memory) is pivoted on either side and just over centre vertically so it flaps up easily from the airflow of the TD. In the many years it's been there it's never been an issue or made a noise.

(Manrose Flat Ducting Pipe Connector With Damper - White, 110mm x 54mm

If there was any part of your rectangular duct that was horizontal you might be able to use the same? I think they also do spring loaded versions that pivot in the middle (like butterfly wings) that might work vertically?

Cheers, T i m

They come in all shapes and sizes:

Chris Green explained on 13/03/2021 :

The only none electrical ones I have seen, all rely upon being vertical in a wall and need gravity to close them/ air flow to open them.

In message <s2ichr$jhv$ snipped-for-privacy@dont-email.me, Harry Bloomfield <?.?@harrym1byt.plus.com.invalid> writes

There are *spring close* versions but the springing must be very light and I think they are limited to horizontal fitting.

We both need the *wax stat* version:-)

Yup. Mine was one of those. A very light spring, and the whole shebang mounted in a horizontal duct.

Tim Lamb was thinking very hard :

I have a wax stat version on our bathroom extract, it works rather well and never any wind noise.

Chris Green snipped-for-privacy@isbd.net wrote

My powered shutter is inside. The external grill isn't shuttered and is just there to keep birds and mice etc out of the duct.

Of got a fan with a waxstat shutter in it, in the utility room It works well. I ought to do the same for the bathroom as that lets in a cold draught