Bryant Plus 90i - Performing Routine Maintenance; Shutting down Your Furnace; Filtering out Trouble

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degrees at the top of your thermostat “comfort level” are
the most costly degrees to obtain.
When the room temperature drops below the temperature
selected on the thermostat, the furnace will be switched on
automatically. When the room temperature reaches the
degree selected on the thermostat, the furnace will be au¬
tomatically switched off.
Some thermostats have a “fan” switch with 2 selections:
AUTO or ON. When set on AUTO, the furnace blower cy¬
cles on and off, controlled by the thermostat. In the ON
position, the furnace blower runs continuously. This
keeps the temperature level in your home more evenly bal¬
anced. It also continuously filters the indoor air.
SHUTTING DOWN YOUR FURNACE
Should you need to shut down your furnace for service or main¬
tenance, you will need to turn the furnace OFF. The following
procedures must be followed:
1. Set your room thermostat to the lowest temperature set¬
ting. (See Fig. 18.)
2. Close the external manual gas valve. (See Fig. 9.)
5. Thrn the control knob on the gas valve to the OFF position.
(See Fig. 20.)
6. Replace the control access door. (See Fig. 14 or 15.)
7. If the furnace is being shut down because of a malfunction,
call your dealer as soon as possible.
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-uring winter. (See winterising procedures in mainte-
PERFORMING ROUTINE MAINTENANCE
With proper maintenance and care, your furnace will operate
economically and dependably. Instructions for basic mainte¬
nance, which can easily be followed, are found on this and the
following pages. However, before beginning maintenance, fol¬
low these safety precautions:
FILTERING OUT TROUBLE
A dirty filter will cause a loss of airflow in your duct system; the
microprocessor will detect an airflow change and compensate
for slight variations. When the microprocessor cannot compen¬
sate for the excessive loss of airflow, a blower calibration fault
will be signaled and the furnace will operate only in the low-
heat mode. If this condition is left unattended, the furnace will
eventually lockout. It is recommended that the furnace filter be
checked every 3 or 4 weeks and cleaned if necessary.
The air filter is normally located in the blower compartment.
(See Fig. 3.) Filters for the downflow furnaces are normally lo¬
cated in the return-air plenum above the blower. If the filters
have been installed in another location, contact your dealer for
instructions. To inspect, clean and/or replace the air filter(s),
follow these steps:
UPFLOW FURNACES ONLY:
1. Turn OFF the electrical supply to the furnace. (See
Fig. 19.)
2. Remove control and blower access doors. (See Fig. 21 and
22 . )
3. Push filter retainer toward the back of the furnace until it
clears the flange on the furnace casing. (See Fig. 23.)
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