With oil appliance sizing, what if the GPH is higher than what’s on the chart?
Unfortunately the sizing chart found in NFPA31 does not go beyond 6 inch diameter pipe. (This was due to lack of funding.) When the GPH is higher than what is on the chart, simple line the chimney using the same diameter as the flue collar size installed on the appliance. The only alternative to this is to get written direction from the manufacturer for sizing the liner to the appliance.
