Y plan system incorporating 28mm V4073A is heating up radiators when CH is off. Have tested actuator and even tried replacing it - same problem. So suspect ball not closing off CH port properly. Honeywell state there is a spare part ball and o-ring part number 272752A/U CARD but I cannot find anyone advertising it for sale and do not see how the ball can be replaced anyway. I do have a spare 22mm V4073A which I can cannibalise. Can I use the same valve top including the plate, spindle, ball and o-ring on the 28mm valve?
When changing this I need to part drain the system. Can I do it in the following manner?
1. switch off power to system at fused spur
2. move lever on actuator to manual position (both ports open)
3. Turn off mains water
4. Run hot tap in kitchen (not sure how long for)
5. change valve parts
How can I tell when enough water is drained out i.e. when the mid port valve is drained?
Is there anything I should watch out for when refilling the system?
When changing this I need to part drain the system. Can I do it in the following manner?
1. switch off power to system at fused spur
2. move lever on actuator to manual position (both ports open)
3. Turn off mains water
4. Run hot tap in kitchen (not sure how long for)
5. change valve parts
How can I tell when enough water is drained out i.e. when the mid port valve is drained?
Is there anything I should watch out for when refilling the system?