system was cleaned out all water was flushed out of system and the correct chemical was added to preserve and protect the system but still it makes a gurgling and knocking sound initially then it quietens to a sort of popping/knocking sound spasmodically but the hot water system is as quiet as a mouse
was it done by a powerflushing machine ? was the complete rad system done ? scale in your hot water is due to dhw heat exchanger needs flushing. kettleing in your boiler will lead tooverheat problem later on.
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