The answer to 'when to replace furnace repair' is that it's generally recommended to replace a furnace when it's 15-20 years old or if it requires frequent and costly repairs. Older furnaces become less efficient over time, leading to higher energy bills and the risk of breakdowns. If your furnace is frequently needing repairs, it may be more cost-effective in the long run to replace it with a new, more energy-efficient model.
Some key signs it may be time to replace your furnace include: the furnace is over 15 years old, it requires repairs more than once a year, your energy bills have been steadily increasing, and the furnace is no longer heating your home effectively. It's best to consult with a professional HVAC technician to assess your specific situation and provide recommendations.