Just realised that with HW only, the rads nearest he pump & valve are warm, but not the whole house.
But with CH on all house rads were getting warm, so valve must be doing something.
When you say check the actuator do I just remove the metal cover to get at this?
Today, with everything cold, I put just the CH on, & both sides of the Y valve warmes up- so I guess this confirms the valve has had it.
Thanks everyone for replies
I think 25yrs is a pretty good service life, so I'll quit thinking and replace the unit. Do you happen to know if a new unit will directly fit the plumbing or have installation dimensions changed over time?
many thanks for your replies
I have a Honeywell y system which is about 24 yrs old but generally still works well. I recently replaced a noisy pump- direct replacement- no problem. Whether its coincidence, but since then the V4073a 3 way is giving hot water to the heating side when only HW is selected on programmer.
Can...