Lately I've been wondering about when I might need to replace my furnace (home heating). I'm thinking it'll die the same year as my first child goes to college, my balloon note comes due, my roof needs replacing, etc., etc. Maybe an educated guess by an HVAC pro will help me sleep better at night.
The unit was built in '83 and installed new in '86. It's a Whirlpool (Heil / Quaker) "high efficiency" gas unit rated at 100K BTU/HR. The model is NUGK100AH01.
I live in central MD. The unit starts running late October gets turned off mid April. I've lived in the house since 95' and have never done anything to the unit...nothing. It has always fired off when called upon an heats my 2500 sf house just fine.
What kind of service should I be doing and at what intervals? About how many years do these things last?