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If you’re in
the market for buying an energy efficient heating system, be
prepared for the new terminology that’s emerged from the industry
over the past decade.
New
technologies associated with burner controls and the furnace fan
motor can perplex potential buyers. Knowing what the new
terminology means will help you understand the options available
on today's heating systems, and will give you peace of mind that
you’re making an informed purchase.
Today’s heating
systems are manufactured as single-stage, two-stage or modulating
units. These terms refer to the extent and flexibility the gas
valve has on the overall burner operation. The greater the
flexibility, the more efficient the furnace will operate.
Single-Stage:
operates with very little burner flexibility. Basically, the
burner is fully on (operating at full fire) or fully off. Older
conventional furnaces in many homes still operate in this manner.
Two-Stage:
is much like having two furnaces in one. During mild winter
weather when the demand for heat in the home is low, the burner
operates at low stage. During colder temperatures, when the heat
loss in the home is at its greatest, the burner adjusts to its
higher stage (full capacity). This system cycles the furnace on
and off more effectively, offering increased energy savings
compared to a single-stage furnace.
Modulating:
with modulating systems, as in some boiler applications, the
burners have the most flexibility in adjusting to heating
requirements (moving up and down in relation to the home's heating
demand). This system offers greater efficiency and comfort
compared to single- and two-stage gas valve systems.
Unlike the gas
valve (which directs and controls the amount of fuel used) the fan
motor delivers heat throughout your home through the duct system.
Today's furnaces are equipped with single-speed, two-speed or
high-efficiency, variable-speed fans.
Single-speed:
delivers heat at one constant speed, whether the fan is set to run
continuously or only when the furnace is operating.
Two-speed:
fan runs
at one of two levels - low or high. This system allows for
continuous air circulation and more even temperatures when the
furnace burners are off.
Variable speed:
enables
the heating system to operate at higher and lower speeds. The
speed of the fan varies depending on the heat demand. Temperature
swings, as well as uncomfortable hot and cold drafts, are
eliminated. Less power is used to run the fan over single- and
two-speed types, which means a reduction in electricity costs.
If you are
choosing a system where you would like the fan motor to operate
continuously, consider opting for a direct current (DC) motor over
an alternate current (AC). A DC motor is more expensive to
purchase but it uses about one-third the energy of a typical AC
motor. |
