Baxi Bermuda 51/5 pump always on

[bogenbroom]

I would be grateful for any advice on this before I contact a local heating engineer.

I have a Baxi Bermuda 51/5 back boiler, room thermostat and Honeywell ST6400C programmer and I believe it is a fully pumped sytem.

The problem is that with everything in the off position the pump is always working and hot water in the surrounding pipes, CH does not come on so assume diverter valve is OK? Only when I turn off fused supply to system does the pump stop.

Kind regards

 

[ChrisR]

As far as I can see the pump and boiler should be wired together, as there's no "pump overrun" after the boiler stops.
If the boiler comes on and off as it should, that points to a wiring error.

 

[bogenbroom]

Thanks ChrisR,
I'll check the wiring best I can but nothing has been changed since first installed - could it have been setup to run hw all the time?

 

[gas4you]

I'd check the zone valve/ 3 port valve, as if the surrounding pipes are hot as you say the boiler must be firing as well as the pump on.