Please help. When Heating on no hot water and vice-versa with Drayton 27101 - 3 port motorised valve

[allysunlife]

We have a Drayton 27101 - 3 port motorised valve 22mm compression

Issue: when heating switches on there is no hot water, when you switch heating off you get hot water.

I replaced the motor in the motorised valve, everything started to work like it should. But an hour later and the same problem. I went back and the pin was moving up and down and corresponding happily. That's now confused me.

Is there another step I can try before replacing the entire Motorised Valve which means purchasing an expensive replacement, draining the entire system etc. Heat only boiler with tank in loft and cylinder on first floor.

I would really appreciate a response as this problem has been going on for a while.

 

[John.g]

If you can use a M.Meter this may be a help.

Y Plan central heating system

Y-plan central heating system operation and wiring diagram

flameport.com

 

[Deleted member 120897]

Are you sure it would need a drain down? If it’s not that old, and looking up that valve, seems like the head can be replaced?