Tech Bulletin

1 TB-150
10/2018
Technical Bulletin 150 - Understanding EF and UEF
The Department of Energy (DOE) is responsible for
dening and implemenng energy conservaon
standards and tesng procedures for various equipment
and appliances, including water heaters.
On June 12, 2017, the DOE introduced a new metric for
communicang the energy eciency of residenal water
heaters called the Uniform Energy Factor (UEF), replacing
the previous Energy Factor (EF). All manufacturers were
required to report and list their UEF numbers as of this
date.
UEF applies only to residenal water heaters.
Commercial water heaters connue to be rated on
Thermal Eciency.
Why are the Rangs Dierent?
While both EF and UEF measure the energy eciency of
the water heater, it is the tesng procedures that are
dierent. The main dierence is that the new test
procedure for UEF is intended to:
• Beer represent how people use hot water today
• Make it easier to compare one water heater to
another
• Simplify the selecon process for consumers
How is the UEF Rang Calculated?
UEF rangs are determined by assigning water heaters
into one of four categories of hot water based on their
usage and then evaluang their performance based on
that usage. Each category has a specic hot water draw
paern and a water heater is assigned a category based
the hot water delivery capacity. A greater UEF rang will
indicate that the water heater in that category is more
ecient.
All Energy Guide labels now include updated
performance informaon to help consumers and
contractors choose the water heater that best
accommodates their needs. It is important that
consumers and contractors understand that the change
to UEF rangs is only a change to the way water heaters
are being tested, measured, and communicated. Rinnai
Tankless Water Heaters remain as ecient as they
always have been and are built with the same quality
that our brand is known for.
Rinnai UEF Rangs
Although the DOE minimum eciency level has
changed from 0.82 EF to 0.81 UEF for water heaters,
this only applies to tankless water heaters
manufactured aer June 12, 2017; thus, water heater
models manufactured prior to June 12, 2017 are not
subject to the 0.81 minimum eciency requirement.
Therefore, you can be assured that all Rinnai Tankless
Water Heaters meet the required eciency standards
according to DOE regulaons and can be sold both in
the US and Canada.
The table below reects the transion from EF to UEF
for Rinnai Tankless Water Heaters.