Recently replaced enviro kodiak with osburn 2300.i know its warmer out right now but had somewhat poor draft with the enviro and same with the osburn as temp was around -3 here this morning.i have 9 feet of supervent and 5 feet of doublewall.should i add another 3 feet of supervent and i guess i will need a chimney support as well ?wood is 2 year seasoned pine.