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High Efficiency Gas Furnaces

What is a High Efficiency Furnace?
The energy efficiency of a furnace is measured by its annual fuel utilization efficiency, or AFUE,
which indicates the percent of energy that heats the air traveling past the heat exchanger. A
standard gas furnace with an AFUE of 80%, has only one heat exchanger. Only 80% of the heat
from the burned fuel is added to the air heating the home and the remaining 20% leaves
through the flue as heated gases and water vapor.
In a high-efficiency unit with an AFUE of 90% or more, a secondary heat exchanger removes
the heat from the water vapor. These units may feature other energy-smart features such as
electronic ignition, sealed combustion, and multi-stage operation.
A furnace is part of a system. Other factors such as proper furnace sizing and placement, duct
design, location and sealing and pressure balancing also contribute to the efficiency.
Benefits for Homeowner:
Money Savings When properly sized and installed, efficient furnaces in a new home can
save 10-20% on energy bills while reducing pollution associated with energy generation.
Improved Comfort Properly sized efficient furnaces when combined with proper duct
design and location, duct sealing and pressure balancing, help provide greater comfort.
Improved Indoor Air Quality Furnaces need air mixed with fuel for combustion to
occur. Typical furnaces combine air from their location which can lead to back drafting,
distributing combustion gases throughout the home. Sealed combustion units pull air
from outside and expel the gases with the assistance of a fan, eliminating this scenario.
Placement and Installation
Placement is unique for every home but following manufacturer's instructions will yield the best
results. For maximum efficiency, furnaces should be installed inside the conditioned area of a
home in an area easily accessible for maintenance. Thermostats should be placed away from
direct sunlight, drafts, doorways, skylights and windows.
Proper sizing
For a furnace to work at its rated efficiency, it must not be excessively oversized. It should be
properly sized to fit the home in which it will be placed - not based solely on square footage but
on the home's individual heat loss and gains.

A load calculation can be done with software and should be based on guidelines such as Manual J
from the Air Conditioning Contractors of America (ACCA) or a similar method. Oversizing can
cause reduced comfort, excessive noise and shortened equipment life. After the load calculation
is complete, ducts, supply registers, and return grilles can be selected and sized using guidelines
in ACCA's Manual D or similar method.






Seal and insulate ducts

An average new home in the Northwest loses approximately 15% of its heating through leaky
ductwork. Poor sealing can generate comfort problems, affect air quality, or cause back drafting.
Properly sealed and tested ducts ensure minimal energy loss and maximize equipment efficiency.
When possible, ducts should be located within conditioned space. If they must be located within
unconditioned space (attic or crawlspace), they should be sealed and insulated.
Check and correct airflow
Managing air flow ensures comfort and savings. When too high, duct leakage increases and the
temperature at the register is not sufficient for optimal home comfort. For best performance,
proper air flow of heating systems should be calculated, tested and adjusted, if necessary.

Financial Incentives:

Sponsor:
Amount:
To qualify:
Criteria:
Recipient:
To learn more:
Energy Trust
of Oregon
$150:
Duct sealing

Submit as stand-
alone incentive (not
as part of ENERGY
STAR home)
Furnace must be
<90% AFUE, ducts
sealed and tested
by a trade ally
contractor
Builder,
contractor or
consumer (limit
one per unit)
www.energytrust.org/ES
homes
Energy Trust
of Oregon
$150:
Gas furnace
Submit as stand-
alone incentive (not
as part of ENERGY
STAR home).
AFUE of 90+
Builder,
contractor or
consumer (limit
one per unit)
www.energytrust.org/ES
homes
Energy Trust
of Oregon
$300:
Gas furnace &
duct sealing
Submit as stand-
alone incentive (not
as part of ENERGY
STAR home).
AFUE of 90+,
system installed by
and ducts sealed
and tested by a
trade ally
contractor
Builder,
contractor or
consumer (limit
one per unit)
www.energytrust.org/ES
homes
Oregon
Department of
Energy
Up to $340
Must have
receipt/invoice
AFUE of 90+
* see website for list
of qualifying
products

Consumer
Your tax advisor and/or
www.oregon.gov/energy

How to claim Energy Trust incentives:
1.

Perform a qualifying service or install a qualifying model
2.

Submit an application to the ENERGY STAR New Homes Program with all documentation:
a.

Submit a Stand-Alone Incentive Gas Home and include a receipt or invoice