Carrier 58MVP Installation, Start-Up, And Operating Instructions Manual page 44

2. Adjust manifold pressure to obtain input rate.
a. Remove burner enclosure front.
NOTE: Manifold pressure MUST always be measured with the
burner box cover REMOVED.
b. Remove regulator seal caps that conceal adjustment screws
for low- and high-heat gas valve regulators. (See Fig. 47.)
c. Move setup switch SW1-2 on control center to ON posi-
tion. (See Fig. 25.) This keeps furnace locked in low-heat
operation.
d. Jumper R and W/W1 thermostat connections on control to
start furnace.
e. Turn low-heat adjusting screw (3/32) hex Allen wrench)
counterclockwise (out) to decrease input rate or clockwise
(in) to increase input rate.
NOTE: DO NOT set low-heat manifold pressure less than 1.3-in.
wc or more than 1.7-in. wc for natural gas. If manifold pressure is
outside this range, change main burner orifices to obtain manifold
pressure in this range.
FIRE HAZARD
Failure to follow this warning could result in reduced furnace
life, property damage, personal injury, and death.
DO NOT bottom out gas valve regulator adjusting screw.
This can result in unregulated manifold pressure and result in
excess overfire and heat exchanger failures.
NOTE: If orifice hole appears damaged or it is suspected to have
been redrilled, check orifice hole with a numbered drill bit of
correct size. Never redrill an orifice. A burr-free and squarely
aligned orifice hole is essential for proper flame characteristics.
f. Move setup switch SW1-2 to OFF position after completing
low-heat adjustment.
g. Jumper R and W/W1 and W2 thermostat connections on
furnace control. (See Fig. 25.) This keeps furnace locked in
high-heat operation.
h. Turn high-heat adjusting screw (5/64 hex Allen wrench)
counterclockwise (out) to decrease input rate or clockwise
(in) to increase rate.
NOTE: DO NOT set high-heat manifold pressure less than 3.2-in.
wc or more than 3.8-in. wc for natural gas. If manifold pressure is
outside this range, change main burner orifices to obtain manifold
pressures in this range.
ON/OFF SWITCH
INLET
PRESSURE TAP
Fig. 47—Redundant Automatic Gas Valve
REGULATOR COVER SCREW
PLASTIC ADJUST SCREW
REGULATOR SPRING
HIGH STAGE GAS
PRESSURE REGULATOR
ADJUSTMENT
(
PROPANE–WHITE, 13.5 TURNS
)
NATURAL–SILVER,12 TURNS
LOW STAGE
GAS PRESSURE
REGULATOR ADJUSTMENT
(
PROPANE–WHITE, 9.5 TURNS
NATURAL–SILVER,9.5 TURNS)
MANIFOLD
PRESSURE TAP
A04048
44
Fig. 48—Burner Orifice
UNIT DAMAGE HAZARD
Failure to follow this caution may result in component
damage due to flame impingement of burners and heat
exchangers.
DO NOT redrill orifices. Improper drilling (burrs, out-of-
round holes, etc.) can cause excessive burner noise and
misdirection of burner flames. (See Fig. 48.)
i. When correct input is obtained, replace caps that conceal
gas valve regulator adjustment screws. Main burner flame
should be clear blue, almost transparent. (See Fig. 49.)
j. Remove jumpers R to W/W1 and R to W2
3. Verify natural gas input rate by clocking gas meter.
NOTE: Be sure all pressure tubing, combustion-air and vent
pipes, and burner enclosure front are in place when checking input
by clocking gas meter.
a. Calculate high-altitude adjustment (if required).
UNITED STATES
At altitudes above 2000 ft, this furnace has been approved
for a 2 percent derate for each 1000 ft above sea level. See
Table 13 for derate multiplier factor and example.
BURNER FLAME
MANIFOLD
Fig. 49—Burner Flame
BURNER
ORIFICE
A93059
BURNER
A89020