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      01-16-2013, 01:32 PM   #10
mikeysix's Avatar

Drives: F30 318d m sport
Join Date: Oct 2008
Location: Kirkcaldy

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Briers mate, a 20 rad sealed system should run on pump speed 3. In reality any size of sealed system the pump should be at max. There is no risk of it pumping over into a header tank or drawing air. I know your saying its noisier but its probably due to scale. A cleanser should be added and run for a while then drain the system and add inhibitor and silencer. It may benefit from a powerflush but if all the rads are heating then a cleanser will do. The boiler cycling is due to the pump speed being too low and not clearing the heat away. The boiler stat controls the temperature of the radiators to touch and trv's are controling air temperature in each room. So the higher the boiler stat the hotter the rads will get but the boiler will be on for longer periods and increase gas consumption. Also if the boiler stat is up high and the system is scaled you will get the kettling which is obviously more noise.