9
Fan Switch
Cool/Heat
Switch
Cool/Heat
Temperature
Control Dials
Room Temperature
Thermostat
Operating Your Furnace
Furnace Operation
In the heating mode, gas is burned and the products of
combustion are drawn through a heat exchanger by an
induced draft blower. The flue gases are then exhausted
from your home through a flue pipe system. The
furnace’s circulator blower passes indoor air over the
heat exchanger and then through the conditioned space.
The furnace’s heat exchanger is actually two exchang-
ers, a primary and a secondary, connected in series.
The primary heat exchanger is an “aluminized” tubular
design built for exceptional durability and efficient heat
transfer. The secondary heat exchanger, sometimes
referred to as a recuperator coil, is a stainless steel tube
and aluminum fin arrangement designed to remove the
last remaining heat from the flue gases. The amount of
heat withdrawn from the flue gases is so great that the
gases are actually cooled to the point of condensing.
This furnace therefore produces condensate (water) which
must be directed to a drain. Furnaces of this type are
referred to as “condensing furnaces”.
Thermostat Functions
There are many types and styles of thermostats but the
operation is usually similar. BE SURE TO BECOME
FAMILIAR WITH YOUR THERMOSTAT. The simplest
type of thermostat only starts and stops the furnace to
maintain the desired room temperature. The most widely
used types will control both heating and cooling functions
and will have a Fan Switch with Auto and ON settings.
On Auto, the circulating air blower will cycle on/off with
the furnace but if switched to ON it will run continuously
regardless of whether or not heating or cooling is being
provided.
In addition, there are thermostats which automatically
switch from heating to cooling mode and those with night
set back capability. The night set back, or multiple set
back, type allows for a different temperature at night or
during the day when no one is at home. Programmable
thermostats will allow for more control and tailoring of the
heating and cooling functions. The level of this control
will depend on the type of thermostat applied.
WARNING
Electrical components are contained in both
compartments. To avoid electrical shock, injury or
death, do not remove any internal compartment
covers. Contact a qualified servicer at once if an
abnormal condition is noticed.
Notice:
Do not use this furnace if any part has been under water.
Immediately call a qualified servicer to inspect the
furnace and to replace any part of the control system and
any gas control which has been under water.
Keep both doors in place except for inspection and
maintenance. An interlock switch prevents furnace
operation if the blower door is not in place.
Integrated Control Module
This furnace is equipped with an integrated control
module which regulates all furnace operations. The
control responds to input from the thermostat, initiates
and controls normal furnace operation, and monitors and
responds to all safety circuits. The integrated control
module is outfitted with a 3-amp fuse for electrical
protection.
Gas Valve
The gas valve regulates gas flow to the burners in
response to input from the integrated control module.
Igniter
The furnace has an electronic ignition device which lights
the burners automatically, never try to light the burners
by hand.
Blowers
An induced draft blower is utilized to draw flue products
through the heat exchanger and exhaust them outdoors.
The circulator or main blower passes indoor air over the
heat exchanger and throughout the conditioned space.
Both blowers are permanently lubricated, no further
oiling is required.
System
Switch
Fan
Switch
Action
OFF
AUTO
None
COOL
AUTO
System only cools, fan
cycles off and on.
COOL
ON
System only cools, fan
runs all the time.
HEAT
AUTO
System only heats, fan
cycles off and on.
HEAT
ON
System only heats, fan
runs all the time.
OFF
ON
No heating or cooling,
fan runs all the time.
Typical Thermostat
Summary of Contents for GULA
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