Flexvent 1/2

Purchased this to replace the old barrel design plastic air vent on my central heating system that was leaking. It took considerably more effort to bleed and refill the system (and getting rid of the subsequent air locks), than to fit this. A couple of layers of white plumbers tape, and it fitted perfectly without any leaks. It is clearly better built than the plastic valve as well, and operates much better. Although it doesn't come with any instructions, if you download the Flamco manual it recommends that you loosen the cap before filling the system and tighten afterwards. The location of the valve is critical as well, it should be on the highest point of the system after the water pump to prevent air being drawn into the system. While not a "Silver bullet" for a central heating system with an airlock issue, the Flamco was not designed to be that. There are many reasons for airlocks occurring in a domestic CH scenario, and an airvent valve may or may not be the solution. If you purchase it as a replacement part with this in mind, you won't go wrong.

Great

Easy to install and seems to work. Give it 4 weeks and I'll come back and buy a few more if it successfully clears air buildup in my manifolds.

Discovered a leaking valve at 7pm, ordered this one at 8pm and it was delivered at 8am the following morning. Valve exchanged and no more leak! Very happy with the product itself. It appears to be the latest version of the one that failed, and that one was fitted over 20 years ago.

Make sure you buy the right size according to your pipework and use case - there is a 3/8" and 1/2" version These are excellent at getting air out of the system and really work. I have an unvented cylinder in my loft and have fitted this on the primary circuit at the highest point in the system. You can hear it work on air immediately and my system has never had any air locks or required time consuming purging even after a full drain down and fill. I suggest using Loctite 55 instead of PTFE for sealing the thread.

Simple to install yourself, has a ptfe collar built in, tighten to the lip, but don't compress/overtighten the ptfe lip, so only needs a tiny 1/2 width tape over the thread

No loss fitting, no need to drain system. 'O' ring seal, hand tight no tools require to replace it (in my case).

I bought six of them and fitted with a professional instaler. One of them had a leak and I needed to drain the system again and instal a spare one from another manufacturer. They need to have a better quality control.