DIY Doctor UK DIY Forums

I had a new combi boiler fitted a couple of years ago.
It worked beautifully until last week when it started to kettle. It cut out - presumably it tripped an overheat thermostat.
I was told by the well known company that the system needed desludging which seemed odd because I thought it should have been desludged prior to the new boiler being fitted.
Is desludging before fitting a new boiler optional, good practice, best practice or obligatory?
Should the pump circulating the water be fitted so the large screw is facing horizontally or vertically?
Since the well known company couldn't do anything for 10 days I looked elsewhere & on recommendation had someone do the job today
£££s but I'm warm again and wish I had trained as a plumber instead of being a pilot

Any decent plumber/heating engineer would flush a system before connecting a new boiler to it.

If there was any sign of sludge etc... then a cleanser should have been added and the old boiler and ran for a few days to a week to cleanse the system.

Then flushed thoroughly before fitting the new boiler. The system should then have been flushed a few times hot and cold to remove the flux etc used when installing the boiler and pipework - then inhibitor should be added.

Hope this helps

Thanks for your reply. It's common sense really.
Well - it appears none of this was done - except perhaps draining the system so I'm slightly disappointed and out of pocket.
I'll stick with my new found plumbing friends even though they are a little pricey