Bungs in central heating to allow rad valve replacement.

[gary.q]

Hi everyone,
If i put a bung in the vent pipe in the central heating f&e tank and another in the cold feed from this tank to the boiler, will this allow me to change a couple of rad valves without draining down?

 

[seco services]

yep once you have created a vacuum

 

[gary.q]

Thanks very much for rapid response. Presumably to create the vacuum I drain out some water. Can I then replace one rad valve then move onto another rad (I have 3 to replace for trv's) without any further vacuum issues? I'm thinking that air can get in whuile replacing the valves and affect the vacuum, or am I barking up the wrong tree with that idea?

 

[JohnD]

when using bungs, you must only ever have the system open at one point or you will lose vacuum. So you can only take one valve off at a time and must close the other.

If you are doing lots of valves, you might as well drain down.

in this case you could add a sludge removing chemical a week or two beforehand and kill two birds with one stone.

 

[gary.q]

Thanks very much fellas. Good advice. I think its as well to drain down then. Cheers.