The answer to 'how often to replace furnace repair' is that most furnaces should be replaced every 15-20 years on average. Proper maintenance and regular tune-ups can help extend the lifespan of your furnace, but eventually all furnaces will need to be replaced as they become less efficient and more prone to breakdowns over time.
Factors like the age, condition, and usage of your furnace will impact how often it needs to be replaced. Signs it's time for a new furnace include frequent repairs, high energy bills, uneven heating, and the furnace being over 15-20 years old. It's best to replace an aging furnace before it completely fails to avoid being left without heat during the cold winter months.