Leaking 3-way mid position valve

[Mezzanine]

My 3-way pump => CH/HW valve is leaking.
What's the quickest and easiest way to fix this?
I can isolate at the pump but I don't think I can isolate the CH or HW loops.
Do I need to drain down the system below the level of the valve to replace it?
Would I be able to use a pipe-freeze spray instead?

Any advice appreciated.

 

[ollski]

what is it....a sunvic?

 

[Mezzanine]

It's a danfoss

 

[ChrisR]

The pump valve will leak if you touch it, almost certainly. Better to freeze or drain - draining's cheaper but can leave you with problems if you have to totally drain. You probably need more inhibitor anyway so money for that not wasted!

If you can move a pipe or two fine, use whole new valve, but sometimes you can't. In which case it's easier to get an identical valve and replace the moving parts, leaving the main casting in situ. It is NOT easy but yo can practise on the new valve. Take the head off, and undo a plate (?) which holds the spindle and moving bits. It's inclined to spring apart in your hand. If you go that ay you can feel old vs new in case there are any grooves etc in the old casting - there aren't usually.

Sometimes you just have to change the whole valve after cutting pipes. May need "Slip Couplings", see BES.ltd.uk.