Standard or full flow service valve?

[sunny_jim_882255]

A major leg (22mm pipework) of the house CH is controlled by a leaking motorised valve.

A drain down is required to replace the valve.

To avoid a similar maintenance problem (and also to allow full shut off of the CH leg) in future, I would like to insert a 22mm service (isolating) valve upstream of the leaking valve.

Problem: Which type of service valve is needed - standard or full flow?

Standard 22mm check (ball) valves have a cross section (when fully open) much less than 22mm dia. - does that constriction matter?

Or is the bulkier full flow valve (eg Scxcrewfix isolating valve - full bore no 43961 pg 466 in current catalog no 106) essential?

[Roger Mills]

Yes, full bore *is* essential. But don't use that one, use one of these:

[sunny_jim_882255]

TFT

But don't use that one, use one of these:

Space available is cramped, though it could be fitted - and it is obviously easier to use routinely (having a handle not a screwdriver head).

Slight downside is the yellow handle which normally means gas to me. Other ball valves in the pipe work have a red handle, but these appear to be discontinued.

but if the issue is reliability/durability then I will go with yellow.

[Toby]

In my experience, the screwdriver type valves you suggested are prone to leaking later on down the line after they are operated, where the one with the handle is not.

You can always cut the yellow plastic cover off, and write on the metal handle what it is for too...

Or buy one with a blue handle

[Roger Mills]

Because if they're not exercised for a while, they can become quite stiff to turn - and the lever provides lots of leverage.

Sorry,I wasn't meaning to recommend exclusively a yellow handle - but just a lever valve rather than one with a screwdriver slot. It was just that the first one I found in the SF catalogue was yellow. If you can find an equivalent valve with a red or blue handle, use that - whatever takes your fancy.

I've got quite a few lever valves of various handle colours in my house. Admittedly, most of them are out of sight - in the airing cupboard or under floorboards, accessible through little access hatches, etc.

[John Rumm]

On anything other than mains pressure it does. So for you application you would be better off with a full bore lever or butterfly valve.

[Arfa Daily]

Or buy some red heatshrink sleeving from Farnell ...

Arfa