Kair 150mm / 6 inch Backdraught Shutter / Ducting Connector with Non-Return Damper Flap - SYS-150 - DUCVKC363 by Kair

There are two basic problems with this product. Firstly it has the SAME radius as the circular duct at the back of a 150mm extractor fan. This means you cannot connect it directly to the extractor fan. You would either need to glue it on or buy a separate female to female adaptor. Even then this product has a second problem.The housing for the valve is too short. The upper and lower flaps on the valve rotates to a position where they extend OUTSIDE of the housing. This means the upper flap would hit the blades of the extractor fan in use. The same issue is experienced if you attach this valve to the ducting on the external side. The lower part of the valve would extend outwards in use and foul on the external air brick.I wanted this product to work. Out of the packet it doesn't. Now I'll need to buy seperate adaptors which would be unnecessary if they had given it a little though.Great idea. Very poorly engineered.

It was fairly easy to fit, you do need to get some large jubilee clips. It does work, but there are problems, when we had some strong winds the shutter went "over centre" and jammed open. I put a small screw in to stop it going too far. When the shutter is open as much as it will go, there is still some restriction to the flow of air. It is a bit noisy when the wind is gusty, opening and closing.

its not sheer or has sheerness so on amazons ratings as sheerness is important to know it loses stars.The unit fits well on pipe, does flap a bit in the windy situations but all in all works well

Brought this to fit in line 150 ducting fitted nicely with wire tiesAnd has stopped the draft coming through But you do hear a tapNow and then on very windy days

Excellent product and service