furnace Types

New furnaces differ on their fuel, design, features and effectiveness.

Ancient single-stage furnaces are being replaced by a newer type of furnaces: multistage and three and two-stage furnaces. These new furnaces offer versatility and can increase comfort and energy efficiency.

These premium furnaces may differ in a set of features that you may want to consider. See: New furnace features and also Multistage, Three, Two and Single-stage furnaces.

Types of furnaces: condensing and non-condensing

Most modern gas and oil furnaces are of condensing type, that is, they can recapture the water vapor and gases they produce, and reuse them, increasing their energy efficiency to levels above 89-90% (98% in the case of some new premium gas furnaces...)

Wall direct-Vent furnaces

Contrary to typical furnaces, direct-vent furnaces are ductless units, and they are a good solution for homes with high levels of air sealing and insulation (and moderate or low heating needs) or for heating hard-to-heat areas like basements, bonus rooms, carriage houses or in-law suites.

The installation of this type of furnaces is easy, since the venting only requires a 3” wall hole...

Rinnai is the major reference in this type of furnaces, sold in many improvement stores and even online (see, for instance: Rinnai ES38-P Direct Vent Propane Wall Furnace">Amazon.com).

Types of furnaces: the energy source

There are gas furnaces (natural gas and propane), oil furnaces, pellet furnaces and, in a sense, electric furnaces.

Gas furnaces are by large the most common and popular type of furnaces. They are clean, easy to maintain and increasingly efficient. New oil furnaces are also very efficient units, but not so easy to use, to maintain or to clean.

New wood pellet furnaces are more than simple improvements of old midwest outdoor wood furnaces. See: Wood Pellet Furnaces.

As to "electric furnaces", they are in fact air heat pumps - a common heating (and cooling) solution, with a technology very similar to that of refrigerators and air conditioners. See: Electric Furnaces.

Types of furnaces: the design

There are several types of furnace designs - down-flow, horizontal, up-flow... - to respond to the requirements of the space where they are going to be installed.