Grunfoss 15-50 Noise

[DirtBag]

Hi all,

Bit of a weird one.... our Grundfoss 15-50 heating pump has worked fine up until this Christmas. One night I thought I could hear a car engine running, but it was the pump. Sometimes it's quiet, but others it whines and vibrates a bit - like the bearings are worn, also a whistle can be heard sometimes.

Now, if you turn off the programmer and the pump stops, you can hear air bubbles, when they stop and you turn on the programmer the pump seems to run quiet.

The pump then runs quiet for a while but after some time starts making the noise again.

So it seems like it's getting air in the pump?

Does that sound correct?

If so what do you think is the cause?

Your views please.

Many thanks in advance.

DB

 

[superdupergasman]

Could either have some debris in the system, some air or a restriction in the pipework causing the pump to work hard or be deprived of water.

Make sure your system is fully blead of air, that the header tank is full or the system filled to 1.5 bar if its sealed.

Switch on all rads and run for a while and the air may clear, blead rads and see how you go!

 

[DirtBag]

I've bled all the rads, the header tank is OK.

It's a vented system.

It sounds OK at the moment, will wait and see in a few hours.

Tnx

 

[MANDATE]

Looked at a problem last weekend and thought pump was related.
Pump would not run when tested from separate power supply.
Removed pump to find both inlet and outlet side almost completely blocked with black crud. These were down to 3 or 4 mm.
Also explains why the pump valves could not be closed.
Suggest you remove pump for examination

 

[ChrisNason]

My 15/50 was making a similar noise. Sometimes it would quieten down but the noise would steadily return. I also found, when it was running quietly, that bleeding the air from the screw provided above the valves just brought the noise back.
I've now fitted a 15/60 and all is silent.