Hi folks,
Quite a common problem, now we are in summer and the Central Heating has been turned off at the programmer, I found a radiator getting hot, when the boiler was responding to demand for Hot Water. However, I have not been able to determine the component causing the problem, and am looking for some assistance.
I have a Honeywell V4073A valve, and as predicted, when the Hot Water tank is calling for hot water, and the boiler and pump are working, hot water is also going via port B [correction, port A - thanks to Ianmcd] to the CH as the CH pipe gets hot. I assume this is either the valve not in the right position, perhaps in the mid position, or the ball inside the valve has worn. So I need to work out if it's just the Actuator/power head that needs replacing, or the valve body (or even just the ball inside the valve).
The wiring seems correct, and the white/grey wires are live when expected for the 3 options of HW, HW+CH and CH only. But when the power is switched off at the Fused spur, and there is nothing live in the wiring box by the valve/pump/hot water tank, and I move the lever in the powerhead, it moves freely with no resistance at all. I have read lots of pages that say there should be resistance when power is off, but I cannot determine the significance of this?
With the lid off the powerhead, I can see movement when changing from Hot Water, to HW + CH, to CH only, so it appears the powerhead is moving the valve. Maybe it's the ball inside the valve that has become worn, and is letting water through into the CH circuit?
If I remove the powerhead completely, with the power off, and move the lever, then there is resistance so the springs are working. So why is there no resistance when it is attached to the valve and has no power? This suggests one of the wires is energised, so I checked the 5 wires going to the valve and none were live. Another test I did was with powerhead removed, I turned the power on, and changed the programmes, and could see and hear movement, although it was quite clunky, and jumped a lot.
When the powerhead was removed, I tried to rotate the spindle in the valve, and it was too stiff for fingers, but moved with pliers.
So, what do you reckon? Is it the actuator/powerhead that is the problem, or the valve? I am happy to buy a new powerhead and fit myself (although not cheap), but would probably get a plumber in for replacing the valve, as it does not have convenient isolation valves, or some that were too stiff for me.
Thanks in advance.
Ian
Quite a common problem, now we are in summer and the Central Heating has been turned off at the programmer, I found a radiator getting hot, when the boiler was responding to demand for Hot Water. However, I have not been able to determine the component causing the problem, and am looking for some assistance.
I have a Honeywell V4073A valve, and as predicted, when the Hot Water tank is calling for hot water, and the boiler and pump are working, hot water is also going via port B [correction, port A - thanks to Ianmcd] to the CH as the CH pipe gets hot. I assume this is either the valve not in the right position, perhaps in the mid position, or the ball inside the valve has worn. So I need to work out if it's just the Actuator/power head that needs replacing, or the valve body (or even just the ball inside the valve).
The wiring seems correct, and the white/grey wires are live when expected for the 3 options of HW, HW+CH and CH only. But when the power is switched off at the Fused spur, and there is nothing live in the wiring box by the valve/pump/hot water tank, and I move the lever in the powerhead, it moves freely with no resistance at all. I have read lots of pages that say there should be resistance when power is off, but I cannot determine the significance of this?
With the lid off the powerhead, I can see movement when changing from Hot Water, to HW + CH, to CH only, so it appears the powerhead is moving the valve. Maybe it's the ball inside the valve that has become worn, and is letting water through into the CH circuit?
If I remove the powerhead completely, with the power off, and move the lever, then there is resistance so the springs are working. So why is there no resistance when it is attached to the valve and has no power? This suggests one of the wires is energised, so I checked the 5 wires going to the valve and none were live. Another test I did was with powerhead removed, I turned the power on, and changed the programmes, and could see and hear movement, although it was quite clunky, and jumped a lot.
When the powerhead was removed, I tried to rotate the spindle in the valve, and it was too stiff for fingers, but moved with pliers.
So, what do you reckon? Is it the actuator/powerhead that is the problem, or the valve? I am happy to buy a new powerhead and fit myself (although not cheap), but would probably get a plumber in for replacing the valve, as it does not have convenient isolation valves, or some that were too stiff for me.
Thanks in advance.
Ian
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