I know several people have written about their boilers knocking when boilers is nearing peak fire and I was wondering if you fixed it and what you did to fix it. Mine is still knocking and I am going to try and purge the air out for about the fifth or sixth time. I have tried circulating a couple of different ways to get the air out. Could my Taco 007 be to small? I have no storage and I am hooked in series with my oil boiler. I installed a coin vent on top of my boiler and have a 1.25 air seperator on my main line. Any pointers would be appreciated. Doug