Find out the gas furnace's AFUE rating. AFUE, or annual fuel utilization efficiency, calculates how quickly the furnace converts its fuel to energy. The higher the rating, the more efficient the gas furnace is.
Consider condensing models for extra efficiency. A condensing unit uses some of the heat that would have escaped from older furnaces and turns it into heat for your home. Condensing models have an AFUE rating of 90 percent or higher.
Choose a gas furnace with a high electrical efficiency. Even though the furnace operates with gas, electricity powers the fan motor. Choosing a gas furnace with a variable-speed fan motor can make the unit more efficient and save you money.
Pick a gas heater sized appropriately for the space you need to heat. There's no benefit to a furnace with a heating capacity too large for your home. Ask an expert to perform a heat-loss analysis to determine the size of gas furnace you need.
Buy your gas furnace from a reputable company. Purchasing even a top-of-the-line furnace means nothing if the company makes mistakes during installation.
- Call your local utility company. It's possible there are rebates available if you purchase a high-efficiency gas furnace. In some cases, these rebates can bring down the cost so it's more economical to buy a more-efficient unit than it is to buy a less-efficient one.