Heating pump making bubbling noises

[bhm1712]

Hi gents,

my CH pump has started making strange noises normally associated with a kettling boiler.
At first i thought it was the boiler, but i have had the pump on and the gas off for over an hour, so the water is circulating round the system cold. The kettling noises are still there.If i put my ear to the pump i can hear the bubbling inside. I have bled the pump and NO air came out, water came rushing out straight away. It does this on all 3 speeds.

the only way i can get the kettling to stop is if i open all lock shield valves fully open.

The system was fine until last night.

any ideas? as i thought pumps either work or they dont...

 

[mickyg]

bubbling in the pump can sometimes indicate dirt in the impellor. If its working ok I wouldn't worry too much

 

[bhm1712]

it works ok, but the noise resounds throughout the whole system and my son is scared of it!

 

[mickyg]

ok well it could be what i said or some other kind of restriction in the flow.
The noise is usually caused by some of the water not being moved and the impellor of the pump simply spinning through it, bit like if you wave your finger around in the same spot in some water you'll create bubbles.

 

[bhm1712]

The pump is 22 years old might be worth changing it anyhow.

i drained the system abour 6 months ago and flushed it with mains water. i the ran it for a day and then flushed it again. I have just checked the quality of water from the lowest point and its virtually clear, just a slight tint in it so i think the system is pretty clean.

i thought it may be cavitating but couldnt see why all of a sudden it would do that after being fine for months.

 

[bhm1712]

question!

on lots of websites you read details of how to check if a pump is running, they normally say " remove the large screw in the center of the pump and you should see the shaft spinning"

wouldnt this mean water would be peeing out everywhere? or do they miss out the bit where they say isolate first?

 

[mickyg]

you'll get a little bit of water out but not alot. That only tells you if its spinning though, not if there's anything wrong with the impellor.

 

[bhm1712]

alot of water comes out of mine, i mean like a high pressure fountain. does this indicate a problem?