Learn how to choose a high efficiency heating system that’s right for you.
The 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.
Minimum Efficiency Standards
Furnace 78% AFUE
Gas-fired Boilers 80% AFUE
Gas-fired Steam 75% 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.
Annual Savings: Simple Payback
If you install a residential warm air furnace at 90% AFUE vs. 80% AFUE, the estimated annual savings in energy costs is $115 with a simple payback of approximately 3 years*.
*Analysis of annual savings provided by the Consortium of Energy Efficiency, a national non-profit organization consisting of utilities, government agencies and energy efficiency groups.
Furnaces with efficiencies over 90% are called condensing furnaces and offer the most energy savings.
These furnaces achieve 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 plastic-type 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 20-30 years, so it is important to choose an efficient model in order to reduce long-term costs. The most efficient boilers forced hot water boilers are considered to have an AFUE rating of 85% or higher. We recommend purchasing steam boilers with an 82% or higher AFUE rating.
Venting Your Heating System
Often times the installation of a high efficiency heating system requires changes to your venting system. It is recommended that you consult with your contractor for proper venting methods.
Guarantees and Warranties
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 two to ten years. High-efficiency furnaces are generally the manufacturer’s top-of-the-line products and have longer warranties.
Sizing Your Heating System
Sizing your heating system should always include the help of a qualified heating contractor. A system that is too large can be wasteful and a system that is too small can’t provide proper comfort. A qualified heating contractor can help you estimate the heat-loss in your home by evaluating the insulation levels and the square footage of wall, roof and floor space exposed to the outside. Then, using the outdoor and desired indoor temperatures, they can calculate the appropriate capacity for your new heating system, measured in BTUs (British Thermal Units) per hour.
Choosing a Heating Contractor
Reliable companies will send an estimator to provide a survey and provide a heat-loss calculation for your home. The contractor should also supply you with a written proposal clearly outlining the work to be done with the agreed upon price and many offer service after the installation is complete.