29
Gas Valve – The gas valve controls the flow of
gas to the burners. When the gas valve is
energized it automatically opens and regulates
the gas pressure in the manifold.
Pressure Switch – The pressure switch veri-
fies that the inducer is drawing the combustion
gases through the heat exchanger. It also senses
a blocked condensate drain condition.
Deck Limit Switch (Auxiliary Limit) – The
deck limit protects the furnace filter tempera-
ture from overheating when the motor has
malfunctioned. If the deck switch opens, the
power for the furnace will shut down (see
Figure 29).
Supply Air Limit Switch – The supply air limit
switch prevents the air temperature leaving the
furnace from exceeding the maximum outlet air
temperature.
Vent Safety Switch – The vent safety switch
shuts the furnace down if the outlet flue gas
temperature increases above 145°F. This
switch protects the plastic flue system and the
inducer from over-temperature conditions.
Flame Roll-Out Switch – This switch pro-
vides flame roll-out protection to the furnace
and combustion air inlet pipe.
MAINTENANCE
It is recommended that the furnace be checked
yearly. At a minimum, this check should include
the following items:
!
WARNING:
To avoid electric shock, personal injury,
or death, turn off the power at the
disconnect or the main service panel
before performing any maintenance.
!
WARNING:
Holes in the vent pipe or heat exchanger
can cause products of combustion to
enter the occupied space. Replace the
vent pipe or heat exchanger if leaks are
found. Failure to prevent products of
combustion from being circulated into
the occupied space can crate poten-
tially hazardous conditions, including
carbon monoxide poisoning, that could
result in personal injury or death.
Combustion Air and Vent System
Check the combustion air and vent pipe to
ensure that it is not damaged, corroded or
blocked by debris. Any damaged section of
vent pipe must be replaced, and any obstruc-
tion or blockage must be removed prior to
operating the furnace.
Air Filter
An air filter is supplied with the furnace as
shipped from the factory. Filters should be
changed or cleaned monthly during the heating
season. New or newly renovated homes may
require more frequent changing until the con-
struction dust has been removed.
Table 12. Accessory Kits
FURNACE ACCESSORY KITS
Kit
Order Number
A/C Coil Box
911969A
Side Return Air Kit
904003
Top Return Air Kit
904015
Sloped Roof VentilAire III Kit
914098
Sloped Roof VentilAire IV Kit
914229
Soffit VentilAire Kit
917201
Concentric Vent Termination Kit
(for horizontal and vertical venting)
903578
Horizontal Exterior Vent
Mounting Kit 3"PVC
902375
Neutralizer Kit - All Models
902377
