Unfortunately, furnaces and air conditioners don’t last forever. Depending on the environment, usage, and service record a forced-air furnace or air conditioner should last between 15-18 years. Eventually, no matter how well you maintain them, you are going to be faced with the decision on whether to repair or replace your system.
Here is a quick rule of thumb that will help you in making that decision. It’s called the $4000 rule. It’s pretty simple. Take the cost of a proposed repair and multiply it by the age of equipment, if it is more than $4,000 then you should consider replacing your equipment.
For example, if you have a 10-year-old system, and you are looking at a $450 repair bill, that will total $4500 using our simple formula. So even though the system may not be at end of life based on average life spans, the cost of repairing it will not have a positive ROI.
The other thing to consider when making the decision is the efficiency of the equipment. For example, if you are replacing a 65% or 80% furnace with a 95% high-efficiency furnace, or if you are replacing a 10 or 12 SEER air conditioner with a 16 or higher SEER air conditioner you will see a marked reduction in your energy bill for the same level of comfort.
