Anti gravity valve

[BobGold11]

Hi, I have an old central heating system that has an “anti gravity valve” that needs replacing. I’m having trouble finding a 22mm anti gravity valve on line and hoping that somebody will be able to point me in the right direction.

thanks Bob

 

[RandomGrinch]

I've got some right next to my glass hammer and the tartan paint!
But seriously, this thread may help:
https://www.diynot.com/diy/threads/anti-gravity-valve-replacement.261938/

 

[Madrab]

If it's the older flapper type (spring or non spring) then they can be very serviceable. May just be scaled/clogged up, what makes you think it's needs replaced, rads getting hot when HW on??

 

[BobGold11]

It started out that one of the upstairs rads was getting warm when the hot water was on and then it progressed to none of the upstairs rads getting hot when the heating was on ! I have taken the valve out and it was well and truly blocked. I decided to change it as the valve is berried behind several kitchen cupboards which have to be removed to access the valve so I wanted to play safe.

It’s been replaced with a check valve and the upstairs rads are getting hot with the heating on but they are also getting hot with just the hot water on.


The old valve had a weighted disk to hold the valve shut. The new valve has a nylon cone but no spring. I’m guessing the light nylon cone is not sufficient to keep the valve shut and allowing thermnosyphing.

Thanks Bob