Noisy ch pump

[Jimbo the Jambo]

Scottish gas fitted a new condensing boiler into our ch system two years ago. We had problems with "rushing water sounds" when pump started and banging and knocking noises up until the pump was replaced last February. We were told to keep venting the radiators for a few days (it took some weeks), however when the pump starts up now it sounds like stones or grit flushing through. On sounding the pump with a long screwdriver between ear and pump body the noise is in the pump. On Friday Scot. Gas carried out a safety check and the gentleman said he thought it could be a stone/s but fixing it was not covered by my maintenance agreement. I fitted the ch system myself 28 years ago and have had little or no problems over the years, the last two have thrown up a succession of niggly problems, this one is annoying.

Any suggestions welcome.

Thanks (this is my first post),

jimbo

[wnjswozo]

power cleanse system

[Jimbo the Jambo]

Thanks for the reply. Scot.Gas did that during boiler installation cost £500 for power flush.

jimbo

[moony]

how old are the rads - they could be corroding from the inside.

[gas man]

could be corrosion or cavitation if not a sealed system please clarify

[Jimbo the Jambo]

how old are the rads - they could be corroding from the inside.

Original rads 28 y.o. but sounding the pipes above and below the pump localise the noise (like broken ball bearings in a bike wheel) to the actual pump.

jimbo

could be corrosion or cavitation if not a sealed system please clarify

Its an open vented system. Scot Gas fitted a magna-clean filter which seems to clean a lot of iron oxide out.

cheers,

jimbo