I have a conventional CH system: gas boiler, Grundfos pump and 2 Honeywell motorized valves controlling separate circuits for radiators (with thermostat-timer control) and HW (timer control).
Here's my problem. The motorized valves close, the pump stops and the boiler shuts down as normal when the required room temperature is reached. But 3 minutes later the pump starts up again with both motorized valves still closed and the boiler off (there's no demand for heat). There's quite a bit of vibration and I find I can get the pump to stop, after a minute or so, if I manually open one of the motorized valves. It eventually stops anyway. It can't be right to have the pump on when both valves are closed, so I suppose this must be a wiring problem (the pump was recently replaced). Any other explanation?
Here's my problem. The motorized valves close, the pump stops and the boiler shuts down as normal when the required room temperature is reached. But 3 minutes later the pump starts up again with both motorized valves still closed and the boiler off (there's no demand for heat). There's quite a bit of vibration and I find I can get the pump to stop, after a minute or so, if I manually open one of the motorized valves. It eventually stops anyway. It can't be right to have the pump on when both valves are closed, so I suppose this must be a wiring problem (the pump was recently replaced). Any other explanation?