Yep replaced that from the crap kit I got, thats what started leaking after 2 days use, so I had to put the old one back on thats when I polished the spindle etc to get the crud off.
But it is the O ring in the castellated nut that is buggered on my original even using grease it is just too...
Nope it is a metal polish just to remove marks on the spindle in the hope that it would move freely, and indeed put back together using SG but to no avail as I said earlier
This one was indeed jammed due too crud so I cleaned it polished it with solvol autosol to get the pitting off but that wasnt the problem, it was the O ring in the gland that was buggered, even after cleaning it was too tight and wouldnt move freely, this was where the service kit came in...
Well I am a qualified sparki and have been plumbing from when I used to go to work with my pop, he used to look after a caravan site, I cut my teeth there repairing burst pipes etc but never bothered with qualies for it, but I do know one end of a tap spanner from the other.
Sympton: Radiators getting hot when only HW is selected and running.
OK so I realise the DV is messing about and not fully closing off the CH loop.
Purchase a DV repair kit, service the DV using all parts from the kit, 1st thing that wont fit is the gland that goes onto the bypass pipe, totally...