Do I need insulation for medium efficiency 75k btu york furnace
Bought an older 2 family home a few years back. We replaced the gas furnace with the same btu, 75k (80% efficiency) and upon install noticed theres no liner in the chimney. Chimney is internal, roughly 30-35' top to bottom where the furnace is. I plan to install one before winter and it seems lile i should be going with a 4" liner from my research. No other appliances will be using that liner. Should I worry aboit insulation or no?
Upstate ny area
Edited to add 80% efficiency. From my understanding natural gas shouldnt cause creosut build up even without the insulation, seeing as it is an internal chimney and not on an exterior wall. Seems to save a few hundred on the install. But I would much rather "buy once, cry once" if it would be advantageous to have the insulation layer as well.