Introducing a two port valve to my semi gravity central heating system

[Tipper]

I did a similar thing many years ago to limit HW temperature and waste of energy on a gravity HW system. A Honeywell valve was inserted in the gravity return to the boiler, near the boiler, and controlled by a cylinder stat. The auxiliary switch on the valve was used so as to interlock the boiler firing thus saving energy. As already emphasised make sure the feed/vent route is not compromised by the valve. I also fitted a pump to the gravity circuit later to improve recovery time after the morning rush in our household. Sorry, I can't remember the wiring details now but no relays were involved just the valve aux switches iirc.

 

[Joe Hardy]

Nigel F

My hot water cylinder was replaced ten years ago - old one weeping

I think there is a coil inside this tank and it's called a fortic or something?

the external pipe connections/ pipework is 22mm - this cyiltol valve is imperial 1" - will I have to do some pipework mods to accept this valve and will this step down in pipe size (25mm to 22mm) affect performance?

 

[Nige F]

OK - you may have a fortic, a cylinder with a cold cistern on top. I am surprised that a gravity circuit is in 22 mm. Conventionally they are 28mm and the cyltrol is designed for that. Under the circumstances I would go with the electric valve, I've fitted many cyltrols but not to a 22mm circuit so can't say how it will perform.

 

[Joe Hardy]

Thanks to everyone who contributed - I am now better informed as to the way forward