Carrier 59SP5A Installation, Start-Up, Operating And Service And Maintenance Instructions page 58

g
e. Follow heat value and specific gravity lines to point of in-
tersection to find orifice size and manifold pressure setting
for proper operation.
f. Check and verify burner orifice size in furnace. NEVER
ASSUME ORIFICE SIZE. ALWAYS CHECK AND
VERIFY.
NOTE: For Canadian altitudes of 2000 to 4500 ft. (609.6 to
1371.6M), use USA altitudes of 2001 to 3000 ft. (609.6 to
914.4M).
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.
g. Replace orifice with correct size, if required by Table 20.
Use only factory-supplied orifices. See EXAMPLE 1.
EXAMPLE 1:0 - 2000 ft. (0 - 609.6M) altitude
Heating value = 1050 Btu/cu ft.
Specific gravity = 0.62
Therefore: Orifice No. 44
Manifold pressure: 3.4-in. w.c.
* Furnace is shipped with No. 44 orifices. In this example, all main
burner orifices are the correct size and do not need to be changed to
obtain proper input rate.
1. Adjust manifold pressure to obtain input rate. (See Fig. 51.)
a. Turn gas valve ON/OFF switch to OFF.
b. Remove manifold pressure tap plug from gas valve.
c. Connect a water column manometer or similar device to
manifold pressure tap.
d. Turn gas valve ON/OFF switch to ON.
e. Manually close blower door switch.
f. Jumper R and W thermostat connections on control to start
furnace. (See Fig. 35.)
g. Remove regulator adjustment cap from gas valve pressure
regulator (See Fig. 51.) and turn adjusting screw (3/16 or
smaller flat-tipped screwdriver) counterclockwise (out) to
decrease input rate or clockwise (in) to increase input rate.
NOTE: DO NOT set manifold pressure less than 3.2-in. w.c. or
more than 3.8 in. w.c. for natural gas. If manifold pressure is
outside this range, change main burner orifices to obtain manifold
pressure in this range.
h. When correct input is obtained, replace cap that conceals
gas valve regulator adjustment screws. Main burner flame
should be clear blue, almost transparent (See Fig. 59.)
i. Remove jumper R to W.
2. Verify natural gas input rate by clocking meter.
a. Turn off all other gas appliances and pilots served by the
meter.
b. Jumper R to W.
c. Run furnace for 3 minutes.
d. Measure time (in sec) for gas meter to complete 1 revolu-
tion and note reading. The 2 or 5 cubic feet dial provides
a more accurate measurement of gas flow.
e. Refer to Table 19 for cubic ft. of gas per hr.
f. Multiply gas rate cu fl./hr by heating value (Btuh/cu ft.)
to obtain input. If clocked rate does not match required in-
put from Step 1, increase manifold pressure to increase in-
put or decrease manifold pressure to decrease input. Repeat
steps b through e until correct input is achieved. Re-install
regulator seal cap on gas valve.
Adjust Temperature Rise
NOTE: Blower door must be installed when taking temperature
rise reading. Leaving blower door off will result in incorrect
temperature measurements.
FURNACE OVERHEATING HAZARD
Failure to follow this caution may result in shortened
furnace life.
Set air temperature rise within limits specified on the rating
plate to prevent reduced life of furnace components.
FURNACE DAMAGE HAZARD
Failure to follow this caution may result in overheating the
heat exchangers or condensing flue gases in heat exchanger
areas not designed for condensate.
Temperature rise must be within limits specified on unit
rating plate.
[]NIT DAMAGE HAZARD
Failure to follow this caution may result in component
damage,
Temperature rise must be within limits specified on furnace
rating plate. Recommended operation is at midpoint of rise
range or slightly above,
This furnace must operate within the temperature rise ranges
specified on the furnace rating plate. Determine the air temperature
as follows:
a. Place duct thermometers in return and supply ducts as close
to furnace as possible. Be sure thermometers do not "see"
heat exchangers so that radiant heat does not affect
thermometer readings. This is particularly important with
straight run ducts.
b. When thermometer readings stabilize, subtract return-air
temperature from supply-air temperature to determine
temperature rise.
If the temperature rise is outside this range, check the following:
a. Gas input for gas heat operation.
b. Derate for altitude if applicable.
c. Return and supply ducts for excessive restrictions causing
static pressures greater than 0.50-in. w.c.
d. Adjust temperature rise by adjusting blower speed.
• Increase blower speed to reduce temperature rise.
• Decrease blower speed to increase temperature rise.
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