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I'm in process of cleaning new installed Burnham 5B 5012boiler. I'm skimming for two hours just cold boiler not running, then running with about one cup of TSP for 8-10 hrs. on page 142 last paragraph Dan's Pocketful of Steam Problems how does one "overfire" the boiler , my vaporstat kicks gas valve into lo at 1/2# boiler keeps running and pressuretroll shuts it off at 1-3/4#. If I'm overfiring what does "firing only to the connected load mean".