How to Check Central Heating Control Valves
CHECKING CONTROL VALVES
The control valve in question may have a coloured indicator or pointer to show it is working. If not, carry out the tests shown here:
Some makes of valve cannot be serviced, and if jammed or faulty must be replaced. This involves draining down the system.
However, on many newer models, it’s possible to replace the entire motor unit (actuator) and free the valve spindle without interfering with the plumbing. Be sure to quote the make and model of the valve when ordering the replacement part.
Wiring in the new actuator flex is the trickiest part. The simplest way is to snip through the flex on the old actuator, then join it to the new flex via a lighting BESA box and block connectors (available from electrical andstores).
♦ Thread the old flex into the box and connect each wire to separate terminals on the block connectors.
♦ Thread in the new flex and connect its wires to the same terminals, matching them colour for colour.
♦ Screw on the BESA box cover and position the box so neither flex is under strain.
1. To replace a detachable valve actuator, first turn off the power. Then, depending on the make, pull off the actuator or unscrew it from the valve body.
2. Check the valve isn’t jammed by turning the spindle with pliers or moving the override lever. Even slight binding may have burnt out the actuator.
3. Cut through the flex at a convenient point and discard the old actuator. Prepare the end of the remaining flex as you would to wire an ordinary plug.
4. Connect the flex on the new actuator to the old flex via a BESA box. Fit the actuator to the valve, aligning the spindle with the slot in its base.