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Central Heating

Stuck zone valve

Fitted new zone valve as it was stuck on . Heating still not working staying on . A-B not moving staying in middle

2 Answers from MyBuilder Heating Engineers

Dear Lynne
I Believed that the valve installed is a 3 port valve.
This valve are operated through a wiring box which are connected to other device as Room Stat and Cylinder thermostat.
They are little bit more complicated to connect, for a 3 port valve, (Y Plan).
Most probably the electrical connection from the valve need to be rectified.
Furthermore, was the valve changed completely or only the Motorized body of the valve?
I hope to have help you
If not please feel free to contact me for a free survey
MA4 Plumbers.


Answered 5th Apr 2015

This requires properly fault finding!
For me it would be a very straight forward process, yet I have 35 years plus electrical & Central heating knowledge !

Firstly, not all 3 port valves are the same !
The most common, being sprung loaded, whereby when the demand comes off of the white wire, ( call for heating), the valve will spring back.

Firstly, you need to isolate the supply to the system, & make sure the programmer is set to both heating & water off.

Turn the cylinder thermostat down & reinstate the power:

Nothing should happen !
Switch the programmer on to constant hot water :
Nothing should happen !
Turn the cylinder thermostat up
and the system should fire, (the valve should be over to the B port ),
Basically the above is repeated for the heating side !
If the system doesn't pass the first stage, then there could quite possibly a fault coming from a wrongly wired / faulty programmer.
Best thing is to post the job on this site .

If you live within 100 miles of Southsea, then please invite us & I will call out and sort this out for you.


Answered 5th Apr 2015

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