Noise from shower....?

[Andy_D]

Went to a job today to remove some radiators and was asked to look at the customers shower. They told me that it's great for the first few minutes then it starts to make a shuddering sound, usually when the water has heated up fully. As the house is quite large there is a secondary hot water circuit. This is switched off however as they said the electric bill was getting silly. Anyway, there was a little leak and some scale on the pump. I tightend up the nut a little and this stopped the leak. I tried the shower again and it took a little longer to start making the noise. I checked the pump again and it seemed to be coming from there and possibly the check valve? Is this possible? Here are some links to videos of the shower and the pump during the noise....

[video=youtube_share;gmLFj4f1znw]https://youtu.be/gmLFj4f1znw[/video]

[video=youtube_share;_hnGsn9tUck]https://youtu.be/_hnGsn9tUck[/video]

It's an unvented system so no shower pump connected. I will obviously go back and change the washer inside the pump, when installing the new rads, as I was not satisfied with just tightening it.

Any help would be gratefully received.

Thanks,
Andy

 

[gassafe]

Maybe the check valve on the secondary circuit causing this... Not seen it before tho

 

[plumben]

Sounds like the check valve is stuck open or just prattling I could be wrong though

 

[Andy_D]

Thanks guys. I presumed as much but wasn't sure so a second opinion is really helpful.

Cheers,
Andy