Carrier Infinity 480CEN024 Installation Instruction page 18

1.The rated gas i nputs shown inTable 4are foraltitudes from
sea l evel to2000 f t above sea l evel. These inputs are based
onnatural gas w ithaheating value o f1050 B tu/ft3 a t0.65
specific gravity, orpropane gas w ith aheating value o f2500
Btu/ft3 a t1.5 specific gravity.
2.For e levations above 2000 f t,reduce input 4percent foreach
1000 f tabove sea l evel. For e xample at2001 f t.a12% total
derate isrequired.
3.When the gas s upply being u sed has a different heating value
orspecific gravity, refer t onational and local c odes, or
contact your d istributor todetermine the required orifice
size.
Ifthe desired gas i nput is115,000 Btuh, only a minor change inthe
manifold pressure isrequired.
Observe manifold pressure and proceed as follows toadjust gas
input:
1.Remove cover screw o ver regulator adjustment screw o n gas
valve.
2.Turn regulator adjustment screw c lockwise toincrease gas
input, orturn regulator adjustment screw c ounterclockwise
todecrease input. Manifold pressure must bebetween 3.4
and 3.6 in.wg. U nsafe operation ofthe unit m ay result if
manifold pressure isoutside this range. Personal injury o r
unit d amage may r esult.
UNIT DAMAGE H AZARD
Failure t o follow thiscaution mayresult in component
damage due to flame impingement of burners andheat
exchangers.
Do Not redrillan orifice. I mproper drilling(burrs,
out-of-round holes, etc.) can cause excessive burner noise
and misdirection ofburner flame. If orifice hole appears
damaged oritissuspected tohave been redrilled, check orifice
hole w ith anumbered drill b itofcorrect size.
ADJUST GAS INPUT
The gas i nput tothe unit i sdetermined bymeasuring the gas f low
atthe meter orbymeasuring the manifold pressure. Measuring the
gas f lowatthe meter isrecommended fornatural gas u nits. The
manifold pressure must bemeasured todeternaine theinput o f
propane gas u nits.
Measure Gas Flow (Natural Gas Units)
Minor adjustment to the gas flow can be made by changing the
manifold pressure. The manifold pressure must be maintained
between 3.4 and 3.6 in. wg.
If larger adjustments are required, change main burner orifices
following the recommendations of national and local codes.
NOTE: All other appliances that use the same meter must be turned
off when gas flow is measured at the meter.
Proceed as follows:
1. Turn off gas supply to unit.
2. Remove pipe plug on manifold (See Fig. 16) and connect
manometer. Turn on gas supply to unit.
3. Record number of seconds for gas meter test dial to make one
revolution.
4. Divide number of seconds in Step 3 into 3600 (number of
seconds in one hour).
5. Multiply result of Step 4 by the number of cuft shown for
one revolution of test dial to obtain cu ft of gas flow per hour.
6. Multiply result of Step 5 by Btu heating value of gas to
obtain total measured input in Btuh. Compare this value with
heating input shown in Table 4 (Consult the local gas
supplier if the heating value of gas is not known).
EXAMPLE: Assume that the size of test dial is 1 cu ft, one
revolution takes 32 sec., and the heating value of the gas is 1050
Btu/ft3. Proceed as follows:
1. 32 sec. to complete one revolution.
2. 3600 + 32 = 112.5.
3. 112.5 x 1 =112.5 ft3 of gas flow/hr.
4. 112.5 x 1050 = 118.125 Btuh input.
FIRE AND UNIT DAMAGE HAZARD
Failure to follow this warning could result in personal injury
or death and/or property damage.
Unsafe operation of the unit may result if manifold pressure is
outside this range.
3. Replace cover screw cap on gas valve.
4. Turn off gas supply to unit. Remove manometer from
pressure tap and replace pipe plug on gas valve. Turn on gas
to unit and check for leaks.
Measure Manifold Pressure (Propane Units)
The main burner orifices on a propane gas unit are sized for the unit
rated input when the manifold pressure reading matches the level
specified in Table 4.
Proceed as follows to adjust gas input on a propane gas unit:
1. Turn off gas to unit.
2. Remove pipe plug on manifold and connect manometer (See
Fig. 16).
3. Turn on gas to unit.
4. Remove cover screw over regulator adjustment screw on gas
valve.
5. Adjust regulator adjustment screw to the correct manifold
pressure, as specified in Table 4. Turn adjusting screw
clock,vise to increase manifold pressure, or turn adjusting
screw counterclockwise to decrease manifold pressure.
6. Replace cover screw.
7. Turn off gas to unit. Remove manometer from pressure tap.
Replace pipe plug on gas valve, then turn on gas to unit.
Check for leaks.
CHECK BURNER FLAME
With burner access panel removed, observe the unit heating
operation. Watch the burner flames to see if they are light blue and
soft in appearance, and that the flames are approximately the same
for each burner. Propane will have blue flame (See Fig. 17). Refer
to the Maintenance section for information on burner removal.
AIRFLOW AND TEMPERATURE RISE
The heating section for each size unit is designed and approved for
heating operation within the temperature-rise range stamped on the
unit rating plate.
Table 5 shows the approved temperature rise range for each heating
input, and the air delivery cfm at various temperature rises. The
heating operation airflow must produce a temperature rise that falls
within the approved range.
Refer to Indoor Airflow and Airflow Adjustments section to adjust
heating airflow when required.
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