Radiator valves banging/whining

[b0ng0]

Hi all,


We had a new replacement Grundfos pump (Grundfos 15-90N) installed late last year. Shortly after, the TRVs on all the rads (although only one at a time) started making a really loud banging/whining/clunking sound when starting to reach temperature.


The valves are Myson One-Way TRVs (about 15-20 years old at a guess). I have tried feeling which pipe gets hot first when turning on the rads and it appears to be the side with the lockshield that gets hot first - which would indicate to me that the flow is going in the wrong direction relative to the TRV position.


I'm a bit confused, as the new pump was an exact replacement of the old one and it's installed horizontally so surely by replacing the pump the water direction shouldn't have changed.


Also worth noting, that there was never any issue before the pump was replaced. Could the new pump have pulled some sludge around the system and its accumulated around the valves?? I'm totally at a loss as to how to proceed with fixing this without doing anything unnecessary.

 

[JCplumb]

Your symptoms scream 'pumping wrong way'
That would be most plumbers first thought in my opinion.
There are less likely reasons to consider, but without knowing more - ideally by a site visit - there's no way to properly say one way or the other.
I'll donate my right plum to charity if a sludge build up has caused all TRVs to be niosy at the same time.

 

[kay-jay]

Your symptoms scream 'pumping wrong way'
That would be most plumbers first thought in my opinion.
There are less likely reasons to consider, but without knowing more - ideally by a site visit - there's no way to properly say one way or the other.
I'll donate my right plum to charity if a sludge build up has caused all TRVs to be niosy at the same time.

I cant think of a single charity that would want either of your plums joe.
You could save it in a pickle jar til its secret santa time.....

To the op. Simple fix to swap your trvs to bi directional.

 

[b0ng0]

I cant think of a single charity that would want either of your plums joe.
You could save it in a pickle jar til its secret santa time.....

To the op. Simple fix to swap your trvs to bi directional.

Thanks for the replies and the generous offer of said plum.

I'm pretty sure the the pump is round the right way (given that it's the same model and all as the old one), could it be that he changed the switch on the junction box and that is somehow messing with the flow?

I take it that the pump flow direction is fixed and can't be altered with some button or switch?

 

[PlumbBobBob]

there is an arrow (or should be) which indicates direction of flow. it is entirely possible that when the original pump was installed the head was changed round to keep the label upright, then if the new one were to be fitted with the label upright without checking direction arrow, flow could be going the wrong way.

 

[b0ng0]

there is an arrow (or should be) which indicates direction of flow. it is entirely possible that when the original pump was installed the head was changed round to keep the label upright, then if the new one were to be fitted with the label upright without checking direction arrow, flow could be going the wrong way.

Yeah I had a look at the whole set-up last night for a while and it really does seem like it's going the wrong way. I take it apart from the valves being in the wrong place, the system can still run "backwards" without damaging anything?