MK7 Automatic Vent Opener

I found the Bayliss Mk 7 to be a very well designed and manufactured product which does its job efficiently and without fuss for a reasonable price. The two I purchased were fairly easy to fit but I did have to manufacture my own aluminium brackets as the ones supplied were too flimsy for use on my wooden conservatory roof windows, which are the maximum designed weight for the product. In use the units are easy to adjust but I did find that the bearings 'cracked' from time to time when in motion and so I lubricated them sparingly with some drops of silicone grease (the kind used to assemble '0' rings into plastic pipework) hoping that this will not adversely affect the nylon in the bearings - it certainly cured the problem and they have now worked well for the first six months. I would expect them to last for many years to come.

Works really well

High quality auto opener. The MK 7 model I bought fitted the existing attachments on my greenhouse and slotted into place easily.

Although it is functioning as it should the mounting bracket holes required elongating before it could be mounted on the greenhouse structure. The adjuster thread had to be cleared of the metal pieces left over from the threading process to prevent the aluminium thread from jamming up as the adjuster was screwed in. Poor quality control by the manufacturers, who I have emailed telling them of the problem but have received no reply! Since this was for a Community Allotment Group with very little money to spend it is particularly annoying. In future we will look elsewhere for a better product.

Good item , exactly replaces old one

I chose the Mk.7 Autovent after reading a few reviews. It is a very good, precision made item, with a lovely finish and it does the job well, opening and closing the window smoothly, with easy adjustment to suit different temperatures. It will open side and roof windows. The major difficulty I had was fitting it, as it is an extremely awkward and frustrating job. It took me 2 full days to properly install, fit and test. At times I was balancing it on my head while using both hands to screw the clamps to the frame. With an Aluminium greenhouse you will have to remove the glass first. You will need safety goggles if you are fitting to an aluminium frame, as the aluminium shards when you are drilling fly everywhere. You will also need a heavy duty 3 or 4mm drill bit for a pilot hole, and a 5mm drill bit to finish, and ideally a small 5mm socket spanner. The nuts and bolts provided are so small and fiddly that if you have large hands and fingers it makes it even more difficult. The instructions are adequate, but could be clearer. They took quite a bit of re-reading to fully understand. The old adage is true here - measure twice, check twice and drill once! It's easy to make a mistake if you are unsure, so 'cautious' is the best approach to adopt. Best to position it first by hand, and mark the drill holes with pencil. This is not a job for anyone without some practical DIY experience, but is probably easier to fit to a timber greenhouse. Overall I am very pleased with it. It opens the window on hot days perfectly well. But you will need lots of patience if you plan to fit it yourself and ideally a willing helper.

Bought ages ago and still works reliably without any attention or need for maintenance.

The original auto vent lasted nearly 40 years before I had to replace it. I purchased this 1 in 2017 and is not working now. I paid £27 for it.