life expectancy gas fired air furnace

life expectancy oil fired air furnace

life expectancy electric furnace

life expectancy cast iron boiler

life expectancy steel boiler

life expectancy circulating pump

life expectancy heat pump(compressor)

oil furnace/boiler clearances

gas furnace/boiler clearances

single wall smoke pipe clearances

double wall smoke pipe

Type B clearance

minimum vent connector rise

Roof clearances for chimney or vent