58
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. (0--609.6M)
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. Wait for blower off--delay to finish then reset 115--v
power to furnace.
q. Jumper R and W/W1 thermostat connections on control
to start furnace.
r. 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
timethenmovesetupswitchSW1--2oncontrolcenter
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.
Table 11 – Altitude Derate Multiplier for USA
ALTITUDE
FT (M)
%OF
DERATE
DERATE MULTIPLIER
FACTOR FOR USA.*
0—2000 (0—610) 0 1.00
2001—3000
(610—914)
4—6 0.95
3001—4000
(914—1219)
6—8 0.93
4001—5000
(1219—1524)
8—10 0.91
5001—6000
(1524—1829)
10—12 0.89
6001—7000
(1829—2134)
12—14 0.87
7001—8000
(2134—2438)
14—16 0.85
8001—9000
(2438—2743)
16—18 0.83
9001—10,000
(2743—3048)
18—20 0.81
*Derate mul tiplier factor is based on midpoint altitude for al titude range.
BURNER FLAME
BURNER
MANIFOLD
A89020
Fig. 62 -- Burner Flame
58MVC
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