In my house, the heater basically stops working every year and my dad put some like “bandaid” solution over it with manipulating some wiring, idk what they do. But like, every year, the heater would stop working like several times throughout the winter and constanly needs to be fixed. But this year it just stopped working completely. Like I google it and those heaters are like $2000 to $2500 brand new, so yea, I get it, parents want to save money, but like, having the heat stop few times a year feels like living in a developing country tbh 😓. So now I’m basically just relying on those portable heater things to stay warm, and my cat is feeling too cold so she’s staying in bedrooms most of the time because its where the portable heaters are at, when she normally just wanders the entire house.
It really depends on the furnace and what exactly is breaking. For example, it isn’t unusual to have to clean or replace a flame sensor every once in a while. Fan motors, sensors, and valves of all sorts will die ocasionally. If it’s a really old one with a pilot light then that can also be a frequent but usually easy to fix issue.
I work in HVAC and I’ve still had mine quit for a bit just about every other year. I’ve had to replace a flame sensor a couple times, a gas valve, a sensor for the exhaust blower, and a fan motor. But my furnace is from the early 90s and was not a high end model even then. Old equipment eventually just starts breaking all over the place but if you have the skills then it can still make sense to just keep limping it along for as long as you can.