Central heating system (banging noises )

[Agile]

The pump is an induction motor which is meant to be a fixed speed motor.

Reducing the voltage increases the "slip" which will do what you want but is not the normal way to drive an induction motor. I suspect it might overheat somewhat.

When you power flush ( properly ) you do it through EACH rad a few times in each direction! Is that what you did?

When you are asked which chemicals you used, the answer is NOT just a desludger, its the exact brand and type! Fernox and Sentinel are the market leaders. Shed own brands are the losers!

Tony

 

[JohnD]

adding to what Agile says, even if you use a good desludger, if the noise in in the boiler it might be limescale or rust deposits rather than sludge, which needs different chemicals depending what it is. I had this with my previous boiler and had a go with acid cleaners myself, but after it was replaced I had a look inside the iron heat exchanger, and the design was such that scale at the bottom was going to be very hard to get out.

However all my efforts had done a very good job of getting all the sludge out!