Pumping when there's no flow.

[stem]

Here's the situation. S Plan that doesn't have a by-pass. One of the motorised valves microswitches sticks 'on' when the valve closes. The circulation circuit is closed, but the pump continues to run constantly. Would this damage the pump? (Presently a Grundfos Alpha 1)

The reason I ask is because it happened. We were there to notice and replaced the motorised valves actuator head, but sometimes the premises are unoccupied during the winter and the heating left on low for frost protection. Would this present a danger if it happened again then but it went unnoticed for several days?

 

[Dan Robinson]

If the heating is running for loooong periods at low levels, a conventional zone valve is not a good thing. You need to use something like the guardian smart valve.