Does that motorized valve have three pipes attached?. If it does then read on.
Three Port Valves for Dummies:
There are a few minor variations but all the three ports I've ever fixed worked in much the same way.
1) The valve rests in the HW only position. The HW demand from the controller switches only the boiler and pump. The tank stat can over-ride the controller and turn that HW demand into a No-HW demand.
2) A CH demand from the controller and room stat goes to the valve motor and drives it to the mid position. At this point a microswitch in the valve head cuts the motor power except for a trickle of current through a resistor; just enough to hold the valve against the return spring. The boiler and pump are already on because of the HW demand.
3) What happens when the demand is for CH only? Well, that microswitch is a change-over type and the motor is now connected to No-HW from the controller. No-HW is a real wire, not just an absence of HW demand. IF AND ONLY IF the motor has already reached mid position, the No-HW demand will drive it on to its end stop, closing the HW flow. But surely the boiler and pump are off? Here comes the clever bit. When the valve reaches the end stop a second microswitch connects the CH demand wire to a third wire going back to the contoller's HW demand terminal. This back feed of power now controls the boiler and pump. On old fashioned electromechanical controllers it will also switch the HW light on which can be a bit puzzling. The valve will stay in the CH position for as long as No-HW is live.
There should be a manual over-ride lever on the valve head. This allows you to open the valve to mid position for filling and bleeding purposes. It is also useful for fault finding.
If you understood all that then you should see that the manual lever will be under tension only if the valve is in the HW position.
Your principal problem appears to be that the boiler/pump will not run without a demand for HW. This suggests, as Mandate has already pointed out, that the valve is not feeding power back to the HW terminal on the controller when it reaches the CH only position. A failed microswitch is a distinct possibility but a jammed valve is another. If the motor is incapable of driving the thing all the way over then the switch won't close and the boiler stays off.
If you're up to it, remove the valve head from the body. It won't leak. You can now test the valve actuating lever for free movement. If it does move freely all the way over then your problem is in the valve head or the external wiring. Sod's law says it's the valve. Do as Mandate suggests and test for power on the orange wire. Remember that this will also be live if you have a HW demand (tank stat included). If you select CH only at the controller, that wire will go dead, the valve will move (you can hear the motor and follow the movement with the lever) and, finally, the wire should go live again.
Three Port Valves for Dummies:
There are a few minor variations but all the three ports I've ever fixed worked in much the same way.
1) The valve rests in the HW only position. The HW demand from the controller switches only the boiler and pump. The tank stat can over-ride the controller and turn that HW demand into a No-HW demand.
2) A CH demand from the controller and room stat goes to the valve motor and drives it to the mid position. At this point a microswitch in the valve head cuts the motor power except for a trickle of current through a resistor; just enough to hold the valve against the return spring. The boiler and pump are already on because of the HW demand.
3) What happens when the demand is for CH only? Well, that microswitch is a change-over type and the motor is now connected to No-HW from the controller. No-HW is a real wire, not just an absence of HW demand. IF AND ONLY IF the motor has already reached mid position, the No-HW demand will drive it on to its end stop, closing the HW flow. But surely the boiler and pump are off? Here comes the clever bit. When the valve reaches the end stop a second microswitch connects the CH demand wire to a third wire going back to the contoller's HW demand terminal. This back feed of power now controls the boiler and pump. On old fashioned electromechanical controllers it will also switch the HW light on which can be a bit puzzling. The valve will stay in the CH position for as long as No-HW is live.
There should be a manual over-ride lever on the valve head. This allows you to open the valve to mid position for filling and bleeding purposes. It is also useful for fault finding.
If you understood all that then you should see that the manual lever will be under tension only if the valve is in the HW position.
Your principal problem appears to be that the boiler/pump will not run without a demand for HW. This suggests, as Mandate has already pointed out, that the valve is not feeding power back to the HW terminal on the controller when it reaches the CH only position. A failed microswitch is a distinct possibility but a jammed valve is another. If the motor is incapable of driving the thing all the way over then the switch won't close and the boiler stays off.
If you're up to it, remove the valve head from the body. It won't leak. You can now test the valve actuating lever for free movement. If it does move freely all the way over then your problem is in the valve head or the external wiring. Sod's law says it's the valve. Do as Mandate suggests and test for power on the orange wire. Remember that this will also be live if you have a HW demand (tank stat included). If you select CH only at the controller, that wire will go dead, the valve will move (you can hear the motor and follow the movement with the lever) and, finally, the wire should go live again.
