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MarGo Plumbing Heating Cooling Inc. Blog

Can That Old Gas Furnace Be Repaired, or Is It Time to Replace It?


As the cold weather sets in, you need your gas furnace to be reliable. If it’s having trouble, or might need a major repair, it’s time to make a very important decision. After all, the last thing you want is to have it break down and need to be replaced in January, when you need it the most.

Before you get into an emergency situation, assess your heating system. Is your old gas furnace worth repairing? Or have you reached a point where investing in repairs is a waste of money? Do you need a new furnace?


There are multiple factors that you’ll want to weigh together when making your decision about whether to keep repairing an aging furnace, and the factor that weighs most heavily is age. A gas furnace can be expected to last for about fifteen years. This is extremely dependent upon how well it’s been cared for, though. 

That fifteen-year estimate is based on furnaces which have received annual maintenance every single year. With no maintenance whatsoever, a gas furnace might only survive for seven or eight years. If maintenance has been occasional rather than regular, the life expectancy will fall somewhere in between.

There are two main reasons for the deterioration over time that happens to gas furnaces. The first is that the more moving parts a system has, the more potential points of failure there are, and a gas furnace has more moving parts than, for example, a boiler. The second is corrosion. Vapors in a gas furnace create an acidic condensate that rusts the system over time.

Repair Needs

Your furnace might require an expensive repair right now. But even if it doesn’t, consider your furnace’s repair history. Has it needed a lot of minor repairs? Have those repair needs gotten more frequent in recent years? It might not be a lot of money at once, but those costs add up, and the older the furnace gets, the more frequently it will require repair.

If your furnace does need a major repair now, consider the 5000 rule. Multiply the age of the furnace by the estimated repair cost. If the answer is under 5000, the repair is a reasonable choice, but if the answer is over 5000, it’s probably not a great investment. 

New Options

The final reason to consider replacement is if new heating options would make it worth your while in terms of efficiency. While regular maintenance can prevent a gas furnace’s efficiency from dropping, at least until it gets near the end of its lifetime, it will never actually make it more efficient than it was when it was new.

Older gas furnaces often had an efficiency somewhere below 70%, meaning that only that percentage of the energy it consumed would be turned into heat. Today’s gas furnaces have efficiency ratings of 85% and higher, sometimes up to 98.5%. This means that a new furnace could significantly cut your monthly utility bills.

Whether your old gas furnace in Livingston, NJ just needs some love from a qualified technician or is headed into retirement so you can replace it with a new, more-efficient model, we’re ready to help so you can be cozy and comfortable this winter.

Contact MarGo Plumbing Heating Cooling Inc. today with any questions about your furnace!

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