grundfos pump not starting

[Tony Clarke]

I know this is an old thread, but I recently purchased the new UPS3 pump, and having exactly the same issue. From day 1, the pump light come on, but just hot a ticking sound from the pump, it wasn't kicking in, causing the boiler to overheat, and causing very loud bangs in the pipes. It is random, was happening virtually every day at some point, but it's not as frequent now, but a concern. I've never left it long enough to see if it kicks in after a few minutes, I just pull the plug off, and reconnect, and it goes, which surely suggests it's nothing in the system, as nothing changed, other than pulling the plug. After several emails with Grundfos, they suggested taking it back to Screwfix for exchange, but not easy during the Covid lockdown.

A similar old thread is https://www.diynot.com/diy/threads/...ement-did-the-same.445747/page-4#post-4631178