The pressure switches are normally-open (closed during
operation), negative air pressure-activated switches. They
monitor the airflow (combustion air and flue products) through
the heat exchanger via pressure taps located on the induced
draft blower and the coil front cover. These switches guard
against insufficient airflow (combustion air and flue products)
through the heat exchanger and/or blocked condensate drain
The flame sensor is a probe mounted on the burner/manifold
assembly which uses the principle of flame rectification to
determine the presence or absence of flame.
To avoid personal injury or death due to
electrical shock, disconnect electrical power
before performing any maintenance. If you
must handle the igniter, handle with care.
Touching the igniter element with bare fingers,
rough handling or vibration could damage the igniter
resulting in premature failure. Only a qualified servicer
should ever handle the igniter.
The furnace should be inspected by a qualified installer, or
service agency at least once per year. This check should be
performed at the beginning of the heating season. This will
ensure that all furnace components are in proper working order
and that the heating system functions appropriately. Pay
particular attention to the following items. Repair or service as
Flue pipe system. Check for blockage and/or leakage. Check
the outside termination and the connections at and internal to
Heat exchanger. Check for corrosion and/or buildup within
the heat exchanger passageways.
Burners. Check for proper ignition, burner flame and flame
Drainage system. Check for blockage and/or leakage. Check
hose connections at and internal to furnace.
Wiring. Check electrical connections for tightness and/or
corrosion. Check wires for damage.
To ensure proper unit performance, adhere to the filter
sizes given in the Recommended Minimum Filter Size
chart or Specification Sheet applicable to your model.
NOTE: Please contact your distributor or our website for the
applicable Specification Sheet referred to in this manual.
Improper filter maintenance is the most common cause of
inadequate heating or cooling performance. Filters should be
cleaned (permanent) or replaced (disposable) every 2 months or
as required. When replacing a filter, it must be replaced with a
filter of the same type and size.
Depending on the installation, differing filter arrangements can be
applied. Filters can be installed in either the central return register
or a side panel external filter rack (upflow only).
A media air filter or electronic air cleaner can be used as an
alternate filter. Follow the filter sizes given in the Recommended
Minimum Filter Size chart to ensure proper unit performance.
To remove filters from an external filter rack in an upright upflow
installation, follow the directions provided with external filter rack
Horizontal Unit Filter Removal
Filters in horizontal installations are located in the central return
register or the ductwork near the furnace.
1. Turn off electrical power to the furnace.
2. Remove the filter(s) from the central return register or
3. Replace the filter(s) by reversing the procedure for removal.
4. Turn on electrical power to the furnace.
Media Air Filter or Electronic Air Cleaner Removal
Follow the manufacturer's directions for service.