What type of valve to balance 1-pipe CH circuit?

[MJA]

I have a mixed 1-pipe and 2-pipe central heating system. The 2-pipe circuit feeds 2 radiators added by a previous owner. It has been difficult to balance as the 1-pipe circuit hogs all the flow. I have now added a balancing valve to the entire 1-pipe system which seems to do the trick. I only had a 22mm compression service valve to hand, and it is not the best type of valve to make delicate adjustments.

My question is, what sort of valve should I be using to balance a domestic heating system? I have found double regulating valves in a web search which look just right, but at over 100 pounds for a 22mm compression valve they are far too expensive for domestic central heating.

MJA

[TheScullster]

"MJA" wrote

This might just be one of the rare occasions where a gate valve could be useful. I know for isolation they are the pits, as they tend to seize shut etc. But in your case, once the right degree of throttling is set, you won't touch the thing again. Also they present less of an inherent flow restriction. I'll wait for the gate-valve-detestors to come and shoot me down now :)

Phil

[<me9]

It will work, but the faces will erode, resulting in it never working again to cut off the flow. Eventually flow will increase as the erosion continues, until full flow is achieved. 5 years maximum I'd give it.

Go on. Report me to the RSPCGV then. I don't care.

[Baz]

If you are going to all that bother to fit a valve, then you should fit the correct one. A GLOBE Valve. Designed for Flow Control. A Gate valve is designed only for Shut Off.

Baz

[Andrew Gabriel]

Yes, gate valves are used for this, one per 1-pipe circuit.

Exactly.

although in this case, it's there for flow restriction!

[NT]

any type, but maybe best pick a full bore one.

NT

[TheScullster]

"Andrew Gabriel" wrote

True, but the reduced bore ball valves for instance present an "inherent" flow restriction before you start throttling. So the control offered will be over a smaller range. Yes I know the purists will say that ball valves shouldn't be used for flow control!

Phil

[Roger Mills]

I would be inclined to replace a short section of the 22mm pipe with 15mm (with suitable reducing fittings) and with a 15mm gate valve in the 15mm section. The smaller pipe *may* provide enough restriction on its own, but the gate valve would provide additional fine tuning.