Looking for advice whether I have diagnosed the problem and whether I should try and fix myself.
Scenario Moved into new house so skint : ( - a few days in try HW and CH both work!!
However, constant 24/7 humming from Mid Position Valve box, manual lever stuck on LHS, when using the programmer to put on HW on its own the CH comes on also.
Does this mean there is a valve stuck? If so how easy is it to check and ultimately fix it.
Would appreciate any help or tips cheers alan
Mid position valves are in two parts. The wet part - which actually directs the water flow - is like a plumbing tee piece with a little shaft sticking out of the top. The dry part - the actuator - is bolted to the top of the wet part, and causes the shaft to be rotated to one of 3 positions - HW only, CH only or both together (mid position).
The actuator contains a motor - which works in one direction only - and a spring to move it back to the HW position when power to the motor is removed.
The first thing to do is to remove *all* power to the heating system, by turning it off at the FCU which feeds the whole system - not at the programmer. If the valve is working properly, the spring will then return it to the HW position. In this position, you should be able to move the lever - slowly - in order to manually move the valve to the mid position.
If it *doesn't* return with all power off, either the return spring is not working or the wet part of the valve has seized up. Remove the actuator from the valve (usually just 2 screws) and see whether the actuator then returns to the HW position when it doesn't actually have to move the valve. If it
*does* return when not on the valve, it usually indicates that the valve is seized. Check how easily you can turn the splindle. It should turn with finger and thumb - or with *light* pressure using a pair of pliers. [Total movement is 90 degrees - with the flat on the spindle parallel with one axis or other at either end of its travel, and at 45 degrees in the mid position] If it is stiff, you may be able to free it by turning it backwards and forwards with pliers - otherwise you'll have to replace the wet bit - which involves a partial drain-down of the system.If the actuator *doesn't* return to the HW position when completely unpowered and removed from the valve, it is duff and will need to be replaced or repaired. Replacement is easy - but make a careful note of where each wire goes in order to connect the new one in exactly the same way.
In message , astewart1 wrote
If you have never seen the system working correctly don't assume that it ever has. The installation may be incorrect and it has never worked properly.
You may have a faulty component, but equally the heating system may have been wired incorrectly.
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