Bryant 580F - Manual (Page 61)

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Adjust the unoccupied minimum position to allow the mini-
mum amount of outdoor air, as required by local codes, to
enter the building. Make minimum position adjustments
with at least 10 F (6 C) temperature difference between the
outdoor and return air temperatures.
To determine the unoccupied minimum position setting, per-
form the following procedure:
Calculate the appropriate supply-air temperature using the
following formula: (TO x OA) + (TR x RA) = TM
TO = Outdoor-Air Temperature
OA = Percent of Outdoor Air
TR = Return-Air Temperature
RA = Percent of Return Air
TM = Supply-Air Temperature
As an example, if local codes require 10% outdoor air during
occupied conditions, outdoor-air temperature is 60 F, and
return-air temperature is 75 F:
(60 x 0.10) + (75 x 0.90) = 73.5 F
Carefully adjust the unoccupied minimum position until the
measured supply-air temperature matches the calculated
value. Then, carefully adjust the occupied minimum position
set point on the controller until the desired position is
reached.
D. Heating, Units With Economizer+
When the thermostat calls for heating, terminal W1 is ener-
gized. The induced-draft motor is energized and the burner
ignition sequence begins. The indoor (evaporator) fan motor
(IFM) is energized 45 seconds after a flame is ignited. When
additional heat is needed, W2 is energized and the high-fire
solenoid on the main gas valve (MGV) is energized. When
the thermostat is satisfied and W1 is deenergized, the
IFM stops after a 45-second time-off delay. The economizer
damper moves to the minimum position. When the thermo-
stat is satisfied, the damper moves to the fully closed
position.
SERVICE
I. CLEANING
Inspect unit interior at the beginning of each heating and
cooling season or more frequently as operating conditions
require.
A. Evaporator Coil
Clean coil as required. Inspect coil at beginning of heating
and cooling seasons.
1. Turn unit power off and install lockout tag. Remove
evaporator coil access panel.
2. If economizer is installed, remove economizer by dis-
connecting Molex plug and removing economizer
mounting screws. Refer to Accessory Economizer
Installation Instructions or Optional EconoMi$er+
section on page 18 for more details.
3. Remove filters from unit.
4. Clean coil using a commercial coil cleaner or dish-
washer detergent in a pressurized spray canister.
Wash both sides of coil and flush with clean water.
For best results, back-flush toward return-air section
to remove foreign material. Caution should be taken
as to not overflow the evaporator drain condensate
pan.
5. Flush condensate pan after completion.
6. Reinstall economizer and filters.
7. Reconnect wiring.
8. Replace access panels.
B. Condenser Coil
Inspect coil monthly. Clean condenser coil annually, and as
required by location and outdoor-air conditions.
One-Row Coils
Wash coil with commercial cleaner. Clean outer surfaces
with a stiff brush in the normal manner. It is not necessary
to remove top panel.
2-Row Coils
Clean coil as follows:
1. Turn off unit power and install lockout tag.
2. Remove top panel screws on condenser end of unit.
3. Remove condenser coil corner post. See Fig. 37. To
hold top panel open, place coil corner post between
top panel and center post. See Fig. 38.
4. Remove screws securing coil to center post.
5. Remove fastener holding coil sections together at
return end of condenser coil. Carefully separate the
outer coil section 3 to 4 in. from the inner coil section.
See Fig. 39.
6. Use a water hose or other suitable equipment to flush
down between the 2 coil sections to remove dirt and
debris. Clean the outer surfaces with a stiff brush in
the normal manner.
7. Secure inner and outer coil rows together with a field-
supplied fastener.
8. Reposition the outer coil section and remove the coil
corner post from between the top panel and center
post.
9. Reinstall the coil corner post and replace all screws.
C. Condensate Drain
Check and clean each year at start of cooling season. In win-
ter, keep drain dry or protect against freeze-up.
D. Filters
Clean or replace at start of each heating and cooling season,
or more often if operating conditions require it. Replacement
filters must be same dimensions as original filters.
CAUTION: When servicing unit, shut off all elec-
trical power to unit and tag disconnect to avoid shock
hazard or injury from rotating parts.
Fig. 37 — Cleaning Condenser Coil