Noisy Pump

I have just replaced my Grunfos 15/60 pump with one of the same make and type. The problem is that there is a pronounced continuous noise from the pipework/radiators. It sounds like the pump bearings. I have bled all the air from the system and the pump is installed as per manufacturers instructions. I have left it on the highest setting as recommended but I am wondering if I ought to try a lower setting. It is part of a Worcester Heatslave 9.24 Combi sealed system and is mounted on an upstairs wall of a three bedroom semi-detatched house. Any comments please????

Even though you have bled through the pump there might still be air in the boiler because the automatic air vent (AAV)isn't working properly. I have to change these a hell of a lot after a boiler drain down as they can stick. Also, when you bleed through the pump make sure you bleed during HW demand and CH demand.

The Worcester Heatslave 9.24 Combi has a pump within the appliance casing. Why is yours fixed to the wall?

Or do you mean that the boiler is fixed to the wall? Not unusual I would have thought.

Thanks very much for your replies gents.

It is my complete Combi unit fixed to the wall, not just the pump.

By the way, does it matter what head the pump can manage if the system is a sealed Combi system (operating at one bar)?

The pump head is necessary to overcome resistances in the boiler, as well as in heating pipework. It must remain on the highest setting (3) for the combi boiler to function properly. The original pump would have had a 6 metre head, as has your replacement. Most heating pumps have a 5 metre head, which would not be adequate for this boiler. The pressure of the sealed system (in your case 1 bar) is irrelevant.