Gas Furnaces – Age makes a difference

December 28, 2017

gas furnace

Many new homes utilize a gas furnace for heating – and many older homes have gas furnaces as well. However, a gas furnace installed in the 1980s (or earlier) won’t be nearly as efficient as the ones in use today.

Over the years, technology and gas furnace design has improved from an annual fuel utilization efficiency (AFUE) rating of 65% to 97%, making them among the most cost-efficient, effective ways to comfortably heat a home. They produce more comfort with far less pollution.

Reliability and durability of a gas furnace

While a gas furnace provides years of reliable service, when one fails, it often needs significant work. Older gas furnaces use a pilot light to heat the natural gas used to provide the heat source for a gas furnace. Modern furnaces often trade in the continually burning pilot light for an ignition with silicon carbide or silicon nitride. Also, in systems with pilot lights, the thermocouple can malfunction, causing the pilot light to go out and require repair.

Repair issues

If you want to repair an older gas furnace, finding the right contractor requires specialized knowledge of a wide range of equipment dating back several decades. An experienced technician can maintain and repair systems to extend their lives for years, but in some cases, replacement is necessary.


When you’re seeking a replacement, it’s good to keep in mind that while today’s high efficiency gas furnaces may cost more, you often recoup the extra cost soon after installation.

A furnace with a 97% AFUE rating can provide significant monthly cost savings on utility bills. A qualified gas furnace technician can recommend the best unit for the size and type of building. The cost should also be balanced against the cost of operation each month to make sure it provides truly efficient heating and cooling for the size of the building.

Unsure whether to repair or replace an aging gas furnace?

In many cases, an old natural gas furnace replaced by a high efficiency gas furnace not only provides a more comfortable heating experience, but also far less pollution for the environment. An HVAC professional can do a thorough view of your system and make recommendations, but ultimately the decision rests with you.

Because of its cost to repair, often a gas furnace can be replaced by a more modern system that provides increased efficiency. This not only saves money but also prevents the electric furnace from constantly breaking down when it’s needed most.


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Last Updated: June 09, 2023