There is a leak from the end flange; I guess there is a gasket or an 'O'ring which has failed. Can anyone confirm this or add helpful information? The pump is labelled 'Grunfos' 'Watermill' and looks like their 'Danube' model but has a blue body rather than the red shown on their website.
Without wishing to question your diagnosis, I would have said a leak at the flange was unusual. More likely to be at the rotating seal where the motor shaft goes into the pump body, or at the flexible hose connection. But it could be that one of the flange parts is cracked.
The first thing I would try is to go round the flange screws and see if any of them seem a bit loose. You should not need much torque to seal on a rubber gasket or O ring.
Having tried that I would be inclined to whip the flange off and have a look at the gasket (take the hose off first). Obviously, you need to isolate the water supply or find a strategy for coping with a bit of water leakage, and switch off the electrics. It's a "big name" pump so spares should be available, but you can often get away with removing the seal and replacing it with silicone sealant, or using sealant over the existing seal. Either way, allow time for curing before putting the water pressure back on.
That can happen if the pump has been left in place when the boiler has been converted to a combi at mains pressure. Pump should be removed when this is done, but that's often overlooked.
In article , Chris Holford writes
Thanks for the helpful replies; I've had another look at it today. I was lucky to spot a drip just forming and it was coming from the outlet pipe connection and running down so it seemed to drip off the flange. So that is a much easier job -fingers crossed! Thanks again.
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