Bryant Condensing Gas 355CAV - Manual (Page 57)

57
UNIT DAMAGE HAZARD
Failure to follow this caution may result in component
damage.
DO NOT redrill orifices. Improper drilling (burrs,
out--of--round holes, etc.) can cause excessive burner noise
and misdirection of burner flames. (See Fig. 61.)
CAUTION
!
h. Jumper R to W/W1.
i. Let furnace run for 3 minutes in medium--heat operation.
j. Measure time (in sec) for gas meter to complete 1
revolution. Note reading.
k. Refer to Table 12 for cubic ft of gas per hr.
l. Multiply gas rate cu ft/hr by heating value (Btu/cu ft).
m. Move setup switch SW4--2 to OFF position and jumper
R and W/W1 and W2 thermostat connections. (See Fig.
33.) This keeps furnace locked in high--heat operation.
Repeat items i through l for high--heat operation.
EXAMPLE: (High--heat operation at 0 -- 2000 ft altitude)
Furnace input from rating plate is 80,000 Btuh
Btuh heating input = Btuh/cu ft X cu ft/hr
Heating value of gas = 975 Btuh/cu ft
Time for 1 revolution of 2--cu ft dial = 88 sec
Gas rate = 82 cu ft/hr (from Table 12)
Btuh heating input = 103 X 975 = 79,950 Btuh
In this example, the orifice size and manifold pressure adjustment
is within +/-- 2 percent of the furnace input rate.
n. Remove jumper across R, W/W1, and W2 thermostat
connections to terminate call for heat.
o. Wait for blower off--delay to finish then reset 115--v
power to furnace.
p. Jumper R and W/W1 thermostat connections on control
to start furnace.
q. Wait for the blower to turn ON then repeat items i through
l for low--heat operation. This setting should not require
adjustment but if it does you will only have 15 minutes
to make the adjustment. If you need more time then move
setup switch SW1--2 on control center to ON position
(See Fig. 33).
NOTE: Measured gas inputs (high heat, medium heat, and low
heat) must be within +/--2 percent of that stated on furnace rating
plate when installed at sea level or derated as stated above when
installed at higher altitudes.
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BURNER FLAME
BURNER
MANIFOLD
A89020
Fig. 62 -- Burner Flame
ALTITUDE
(FT)
% OF
DERATE
DERATE MULTIPLIER
FACTOR FOR U.S.A.*
0—2000 0 1.00
2001—3000 4—6 0.95
3001—4000 6—8 0.93
4001—5000 8—10 0.91
5001—6000 10—12 0.89
6001—7000 12—14 0.87
7001—8000 14—16 0.85
8001—9000 16—18 0.83
9001—10,000 18—20 0.81
*Derate multiplier factor is based on midpoint altitude for altitude range.
Table 11 – Altitude Derate Multiplier for U.S.A.
355C
A
V