Ordinary Honeywell V4073A 3 port mid position valve, apparently operating normally. Hot water goes where it's supposed to go when HW, CH or both are called for. Valve returns to default position when not energized.
HOWEVER, if the last position was CH only and the CH thermostat then stops calling for heat, then the valve stays in position, makes a quiet humming noise and the valve head gets quite warm. No smell, no smoke, no loud noises, but the motor is obviously energised without moving.
Is this normal? Grey wire is energised in this situation, signalling "HW OFF", so having a power supply into the valve head at this point is normal, too.
Any answers appreciated.
HOWEVER, if the last position was CH only and the CH thermostat then stops calling for heat, then the valve stays in position, makes a quiet humming noise and the valve head gets quite warm. No smell, no smoke, no loud noises, but the motor is obviously energised without moving.
Is this normal? Grey wire is energised in this situation, signalling "HW OFF", so having a power supply into the valve head at this point is normal, too.
Any answers appreciated.
