Grundfos Super Selectric 15-60 recently started buzzing

[5imon]

Hi everyone.
Plumbing newbie here, wondering why my grundfos 15-60 has recently started buzzing.
I recently turned up the temp on the boiler and about a week after this the pump started making a noise similar to a fridge. It doesn't sound knackered, it just sounds noisier than it should be. Nothing wrong with the radiators, or hot water temp. Everything else tickety-boo.

I've been trawling the web and there have been a variety of responses regarding adjusting the speed and bleeding the pump.

So here we go:
- How do I bleed the pump?
- I'm a little nervous about adjusting the speed since i understand a slow pump speed can cause kettling. however i also read that the pump can buzz if stuck between speed settings. If I pluck up the courage to try a different speed should I turn everything off first? Or should I do this whilst the CH is on?
- Anyone know any other possible causes of the noise? Are there any other 'settings' I can adjust before trying the heavy jobs, like desludging?


Many thanks in advance. It won't take too much adversity for me to get scared and throw money at the problem by calling a pro in, but I'd like to understand more about the house I've moved into so thought I'd have a go myself.

Cheers

 

[5imon]

ok - I plucked up the courage to adjust the speed.
The noise dropped in frequency, so I've confirmed that the CH pump is the issue.
It kind of sounds like the pump blades scraping against the interior wall of the pump...as I said, not particularly a worrying noise, just annoying.

any thoughts? anyone? anyone?

 

[Hugh Jaleak]

To bleed, open the big silver screw on the top of the pump until water dribbles out, if you loosen the screw too much it will fall out so beware!

If its all working as should be I would leave alone! If pump packs up its not a major problem to replace, the 15/60 is a standard size. May possibly be slight vibration through the pipework from the pump, or a bit of crud stuck within causing the noise.

 

[5imon]

thanks for the tips hugh
i take it that you follow standard procedure for bleeding the pump? ie turn CH and HW fully off, turn pump off then bleed??

agreed it's prob some crud caught in the pump. is there any way to check this without removing the pump entirely?