Gas Furnaces vs. Oil Furnaces

New oil furnaces are far more efficient than those of ten or twenty years ago. But the height of their popularity has long passed and they are being largely replaced by gas furnaces. Anyway, deciding between oil and gas furnaces can still be a matter of discussion.

Gas and oil furnaces vs. electric furnaces

What is now sometimes called electric furnaces are in fact air heat pumps, a good electric heating alternative for moderate climates and in situations where freezing temperatures are rare.

In colder climates, "electric furnaces" only make sense when used infrequently, and basically as a backup. In these cases, their low maintenance requirements and low initial investment are their great advantages.

Otherwise gas furnaces are a much better option.

New oil furnaces efficiency vs. New gas furnaces efficiency

The efficiency (AFUE: Annual Fuel Utilization Efficiency) of new oil furnaces have risen a lot during the last decades. Most new oil furnaces have AFUEs between 80% and 90% - an increase of 20-30% relative to older units. High static pressure burners are at the core of their new technology.

New condensing gas furnaces, on the other hand, have an efficiency above the 89/90%. Gas units with AFUEs of 98% are now relatively common.

This gap of efficiency should be considered, but it may also be rather relative. The higher efficiency of high-premium gas furnaces come at price: they are more expensive... In other words: for the same efficiency, the prices of oil furnaces are rather similar to those of gas furnaces...

On the other hand, the efficiency of a furnace depends a lot on the quality of the installation. Details involving the installation, the ventilation and the ductwork can me more important than the furnace in itself.

Obviously, this doesn't mean that oil furnaces are a better option than gas furnaces. They aren't. It just means that the efficiency of gas furnaces over oil units is small.

Running costs & Fuel Prices

There is a recent trend of prices favorable to gas, that should remain, according to most energy experts. Unless regional trends point otherwise, gas furnaces are a better value in terms of running costs.

Oil Furnace to gas furnace Switching

Oil furnaces are now a relatively clean option, though not as clean as gas furnaces. On the other hand, they also require more maintenance, and large storage tanks, larger insurance costs, and eventually more inspection requirements...

That can make gas furnaces a better option, economically and environmentally.

But switching from oil to gas may pose higher installation costs and requirements (most new gas furnaces use a plastic vent in a side wall, while new oil furnaces require modifications in the chimney and often a sealed-venting system).

You may want to consider these costs, jointly with regional forecasts for gas and oil prices, and the cost of each type of furnace (see: New Furnaces Prices and Payback)...