Kair Round Connector 100mm - 4 inch to Connect Duct Pipe or Flexible Ducting Hose

Perfect and did the job

Perfect for joining 2 pieces of round pipe

I installed this in a vertical duct above my cooker hood. I was getting cold draughts coming in during the winter and this completely solved that problem. There was one small issue in that when mounted vertically it is possible for the flap to open more than 90 deg, tip past the vertical and then stick in the open position. I added a small screw to prevent it opening more than about 85 deg and this seemed to fix that issue.

Great product

2 main problems: 1. The overall manufacturing quality of the product was not as I would have hoped. The plastic molding is poor with a jagged part jutting out of the flap in an area which could potentially interfere with it's closure. See photo. 2. I found that the flap does not swing freely even before being fitted, and there is some resistance even to gravity. If the product is compressed slightly from the outside then the flap does not swing at all and can be held in an open position. Considering that the movement of the flap will only get worse as the product inevitably collects dust and grime I elected not to fit this product and fitted a competitor product of the same mechanism which seemed immediately better quality and performance. N.B. I did bought a second one of these as I wondered if it was a blip but both were the same and were returned.

I bought this when I realised that our new home had a cold draft coming from the cooker hood when it was off. This was a lot of cold air costing money on my heating bill and not environmentally friendly at all! It fitted very easily and size selection was easy as the dimensions are in the photos with the description of the product. The best bit of this is that it uses gravity to close and the fan draft to open. It opens readily with almost instant reaction to switching on the hood even at the very lowest setting. However it does not bang or tap (like some do) when windy. The outlet gets a lot of wind hitting it as it faces west and is an open area prone to strong winds and there is no draft at all through this device. The second great thing is it has no spring due to gravity action for closing. Springs can be a real pain on these types of product so that is good. The only thing to remember is it only works mounted horizontally and get it the right way up! Overall its going to save me lots of cash in reduced heating and its environmentally good thing to do. For those that are interested the device uses offset hinges that have the larger area of the shutter (heavier side) causing the shutter to fall closed, when the fan starts the draft pushes the heavier side open by the small air pressure created and it opens fully. Very pleased with how well this balancing act is executed and can fully recommend. Don't forget to put some tape around any small gaps in the pipes when connecting the ducting to stop even the little drafts from the joints.

Fits perfectly

I had to make some minor adjustments: Sand down the collar until it snugly fit inside the 100mm dia tube. Put graphite powder on the swivel pins and stick a small weight to the bottom of the flap so that it closed sufficiently to stop most of the backflow. The backflow seems to have now significantly reduced... time will tell.