"Heating circulation problems are often due to air locks caused by trapped air pockets at high points in the system. e.g. when a pipe goes up and then down again. The use of this magical air vent in this situation remedies the problem and prevents its recurrence."
"I bought these valves as I kept getting air in my central heating. There were some pipe going over rafters, when I fitted these ARV they cured the problem straight away. The Central heating now works perfectly"
"Bought as a replacement for an identical (?) valve fitted five years ago, which had begun to let water vent as well as air! The replacement was straightforward to fit and appears to be working fine. However, if the earlier valve is identical, I'd question whether the new one will prove to be reliable. Can't be sure it's identical, because Screwfix has a habit of changing suppliers for commodity items, so I may be being unfair here!"
"I tried fitting one of these to vent an up and over section of pipe on my shower to replace a manual air vent.
It fitted easy enough, however it leaked water straight away from the air vent valve on the top, so I had to screw in the plastic stop valve to prevent the leak.
Then having read all the other reviews for the product realised other people had had the same problem so I decided to return it, Screwfix refunded the cost without problem as usual, well done Screwfix.
I replaced with another fitting from reputable manufacturer from a plumbers merchant, no problem with that one, very little price difference as well.
If you use these I'd keep a close eye on them after fitting."