Purchasing a High Efficiency Heating System

The following information is designed to help you make an informed decision about choosing a high efficiency heating system that is right for your comfort, energy savings, and your budget.

A new heating system is a major investment, so make sure you understand the warranties that come with your new equipment. Parts and labor are usually covered by the manufacturer and installing contractor for the first year. Some brands also offer warranties of 2 to 10 years. High-efficiency furnaces are generally the manufacturer’s top-of-the-line products and have longer warranties.

Efficiency Ratings standards are set by the U.S. Department of Energy under the National Appliance Energy Conservation Act of 1987, which became effective January 1, 1992.

All natural gas heating systems have what’s called an Annual Fuel Utilization Efficiency (AFUE) rating. The rating is expressed in percentages. In order to meet code, all new heating equipment must meet the minimum efficiency standards.

Minimum Efficiency Standards

Furnace78% AFUE
Gas-fired Forced Hot Water80% AFUE
Gas-fired Steam78% AFUE

The higher the AFUE rating, the more efficient the heating system — and the less energy needed to heat your home.

For example, a new, high-efficiency furnace with a 94% efficiency rating provides 94 cents worth of heat from every energy dollar. By comparison, an older, standard-efficiency furnace with an efficiency rating of 60% provides 60 cents worth of energy for every dollar spent.

Whether you are installing a high efficiency furnace or boiler, there are important considerations.

Furnaces with efficiencies over 90% are called condensing furnaces and offer the most energy savings. These furnaces achieve a 90% AFUE rating by sending flue gases through a secondary heat exchanger. This device further extracts heat that is usable energy for your home.

Remaining flue gases then exhaust outdoors through special vent pipe inserted through the wall of the home. This “direct-vent” piping configuration also draws in outside air for combustion. Since indoor air is not used in the combustion process, cold air leakage (infiltration) is reduced — an added energy savings.

A boiler can last between 30 years or more, so it is important to choose an efficient model in order to reduce long-term costs. The most efficient forced hot water boilers are have an AFUE rating of 85% or higher.

Often the installation of a high-efficiency heating system requires changes to your venting system. It is recommended that you consult with your contractor about proper venting methods.