While replacing the motor of a motorized valve in the central heating system of my house I have noticed some weird voltages that may be a problem:
Of the three cables (excluding earth) that arrive at the thermostat from the timer near the boiler, the voltage between neutral and life is
140V AC when the timer is off (it is 240V AC when the timer is on).Also, the voltage between neutral and switched life (when not connected to life) is 90V AC. This means than when the thermostat is not asking for heat the motor is always receiving 90V AC (it does get
240V when the thermostat is asking for heat)Should not these 140V and 90V be 0?
Perhaps this explains why this motorized valve broke. If it is permanently energized at 90V it is likely to fail earlier.
I have shorted the neutral and the life, while the timer is off (ie, when there was 140V AC ), with a 1A fuse in between, but the fuse did not blow. So, it seems that there is no big intensity behind that voltage.
I have confirmed at the junction box near the boiler that the 140V is not coming from the side of the timer.
I have also confirmed that for other zones ( I have five at home) the voltage is 0 for three of them and about 115V for the fourth one. This
115V is for a zone where the motor also failed some time ago.Where are these voltages coming from?
Are they a problem?
How can it be fixed?
Needless to say that it is not possible to access all the wiring between timer and thermostats and motorized valves. Even the junction boxes near the motorized valve is very difficult to access.
Many thanks,
Antonio