This problem started happening only recently. It happened for a week or so last month then stopped and now it's started again.
The installation is a Worcester Bosch boiler installed some 5 years ago in a gravity system. The system was converted to a closed system when a megaflo was installed about a year and half ago. In all this time everything was working absolutlely fine until now.
To explain when the vibration sound begins. The HW heating is off by this time and only the CH is on. When temperature is reached (the CH light goes off on the programmer), and the boiler shuts down and that's when the buzzing vibration sound begins until the pump stops after a minute or so (guess it's normal for the pump to run for a bit after the boiler shuts off).
When the boiler shuts down and the pump is still running, should both control valves (CH & HW) be closed? When the vibration occurs I've pushed the manual override on the CH valve to 'open', the vibration and sound stops.
The installation is a Worcester Bosch boiler installed some 5 years ago in a gravity system. The system was converted to a closed system when a megaflo was installed about a year and half ago. In all this time everything was working absolutlely fine until now.
To explain when the vibration sound begins. The HW heating is off by this time and only the CH is on. When temperature is reached (the CH light goes off on the programmer), and the boiler shuts down and that's when the buzzing vibration sound begins until the pump stops after a minute or so (guess it's normal for the pump to run for a bit after the boiler shuts off).
When the boiler shuts down and the pump is still running, should both control valves (CH & HW) be closed? When the vibration occurs I've pushed the manual override on the CH valve to 'open', the vibration and sound stops.