Grundfos 15-50 pump suddenly noisy

[badfloor]

Hi All,

We have a traditional gas boiler, three way valve, vented heating and hot water system. In the last few days the pump has started making a mechanical noise like this (click to listen).

It always happens when the system kicks in at 6am, but then stops after a few minutes and everything seems normal but often the noise will return an hour or so later and carry on. If I stop the system and leave it for a few minutes, the noise continues when I restart it.

I've bled all the radiators multiple times to eliminate as much air as possible.

While it's making the noise, water is still being pumped and the radiators and hot water get warm.

The system was installed in 1991 when the house was built and I can't be sure it's the original pump, but it's been at least there since we moved in 8 years ago.

Is this likely to just be a dying pump, or is there something else I might have missed?

Thanks in advance,

badfloor (and yes, the floor is still bad)

Edit: Forgot to mention I've bled the pump too and water dribbles out.

 

[Slugbabydotcom]

It's either the beginning of the end for your pump or there may be a bit of debris getting stuck in it.

 

[badfloor]

there may be a bit of debris getting stuck in it.

What sort of debris would be in it? We have very soft water here so I'm not convinced it's limescale.

 

[mfarrow]

It's usually rust and debris which has been circulating because of a lack of inhibitor, which finds its way into boilers and pumps.

I would add some inhibitor and take the pump apart to clean it. These are very simple machines and if you just wipe it out inside it might come good.

 

[badfloor]

I would add some inhibitor and take the pump apart to clean it. These are very simple machines and if you just wipe it out inside it might come good.

That's great! I'll do that and see what happens.