Strange clicking from circulating pump/three-way valve

[JonS]

I had a new oil fired HW and CH system installed about 4 months ago and from day 1 there has been an annoying clicking/light tapping sound coming from the region around the pump/three way valve when the boiler is providing HW only. The sound is tinny and does stop for 10-20 seconds from time to time. If I have the heating on, the sound dissappears altogether. Switch out the CH and the click returns.

I had the plumbers back and they fitted a new valve head and then a new 3-way valve. The ticking became slightly more intermittent and I was told that the cause was probably a ball of solder trapped somewhere around the pump area. I was told that eventually the ball would find its was into a rad somewhere in the system and the noise would stop. This seemed rather a tall story to me at the time but I needed to get back to work and I let it go.

Anyway, needless to say the noise is still with us and its getting more annoying by the day. Now that I've given it some thought it looks more and more like the impellor rattling on the circ pump. (Grundfos high head) When the CH is switched in the circuit resistance increases and the increased pumping effort required quietens it down. I want to get the plumbers back to change the pump as its still under warranty and they never really sorted it out the first time around.

It would be good to be armed with some knowledge on this before speaking to them and I haven't been able to find any previous posts on this topic.

Has anyone come across this type of thing before? Am I on the right lines with the pump or could the solder ball story be legitimate?

Many thanks for any ideas or feedback.

 

[Nige F]

Solder ball could be legit

 

[JonS]

I guess as its been summer since the system went in, the route round the rads hasn't been used in earnest and there is nowhere for the ball to get trapped in the HW loop. Maybe I'll hang fire until next spring and see what happens.

Cheers.

 

[JonS]

But if it is a ball of solder, why does the noise stop when CH is switched on but comes back as soon as HW only selected?

 

[kevplumb]

put your ear to the valve head is that whats clicking

 

[JonS]

The valve and head have been replaced as this was were I thought the noise was coming from originally. Trouble is the sound travels all along the copper and pinpointing it is difficult. Since the boiler is outside and the pump, valve and head are inside it has to be one of the latter 3 things, or the solder lump...


Cheque cleared a while ago now

 

[oilman]

try moving the gate valves either side of the pump a little.

 

[JonS]

After playing with the upper gate valve I found the internals of the valve to be very loose. Closing in lets the valve flap about more in the flow and the noise increased. Forcing the valve fully open made the noise dissappear.

I'll be getting the plumber back to replace the defective valve.

Thanks to all for the advice, especially oilman. The clicking has finally gone.