Intermittent boiler banging, knocking noises ...
2015-3-17 · I have an Allied Superhot SG 135 boiler with 6 zones. The boiler is 15 years old and has been making banging and knocking noises. My plumber has changed the pump, the relay, the expansion tank and the aquastat. He has rerouted the cold water feed to the supply side of the boiler from the return side.
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