It's another component that can fail on you on the coldest night of the
year, over a holiday weekend, fouling up your vacation or christmas
Tell me if your precious, modern furnaces with their ECM fan motors save
electricity when they also have to have these draft motors running.
Hmmm. Here's a PSC (!) draft motor, consuming 80 watts. I hope you're
factoring in this 80 watts into your furnace's electricity use.
And also note the reference to "government-mandated efficiency
standards". Like I said before, the modern furnace being sold today is
not the result of pure market-driven competition from a design and
construction point of view.
These blowers were not necessary on old furnaces. However,
once the government mandated furnace efficiency standards
beyond what natural convection could handle, the draft
inducer was created. This enabled specific control of how
much air moved through the heat exchange unit. That, in
turn, made it possible to determine BTUs and the AFUE and,
thus, the unit's efficiency.
Crock of shit.
What Is a Furnace Draft Inducer Blower?
By Arlene Miles, eHow Contributor
updated: June 25, 2010
A furnace draft inducer blower is a relatively new component of modern
furnaces that became part of heating units after government-mandated
efficiency standards were enacted. The draft inducer blower's purpose is
to move air and gases out of the furnace and up through the chimney.
This component determines how much and how fast air will move through
the heat exchange unit.
Although variations occur, typical draft inducer blower is located in
the gas burner compartment of a furnace and consists of a motor-driven
wheel assembly or fan, an electrical box for power connections and a
metal sleeve surrounding the assembly. Variables include size of vent
pipe diameter, voltage, amperage, wattage, horsepower, and size of the
cutout needed for the unit.
Draft inducer blower components are made of durable plastics and metals,
or a combination of both. Polypropylene is used to manufacture
industrial draft inducer blowers used in corrosive environments because
this plastic resists corrosion better than other materials and will
never delaminate. Fiberglass is also used when the component must
withstand temperatures above 220° F. Blower size is determined by the
size of the unit in which it is located.
As the furnace enters start-up mode, the draft inducer blower begins to
purge the heat exchanger of gases that may have remained in that area
during the furnace's previous heating cycle. This makes the air in the
area cleaner at the time of combustion and also prevents furnace burners
from becoming clogged with soot. By improving the quality of air moving
through the furnace, the draft inducer blower helps improve efficiency
of the system.
When a furnace begins a new cycle, the draft inducer blower fan begins
whirring 30-60 second before the furnace burners actually ignite. The
fan motor must also run properly and usually has a safety pressure
switch connected to the fan housing. Pressure switches ensure that the
motor is running according to the manufacturers' specifications. If the
inducer fan motor cannot turn on, the furnace will generally shut off
and lock out. Several other reasons may also cause the draft inducer
blower to ultimately shut down a furnace. These include a faulty
pressure switch, a bad rubber tube component, or there may be a blockage
in the gas vent flue, or even the blower itself may not be working
Because many draft inducer blower models are nearly impossible to
rebuilt, an entirely new unit must be purchased in most cases when one
wears out. The exceptions to this rule, according to Furnace Parks USA,
are units manufactured by Carrier and Bryant.