Set Gas Input Rate - Carrier 58MXA Installation, Start-Up, And Operating Instructions Manual

NOTE: I f TEST/TWIN andCOM-24V terminals are jm_apered
longer than
2 sec, LED will flash rapidly and ignore component
test request
Component test sequence is as ibllows:
a. LED will display previous stares code 4 times.
b. Inducer motor starts and continues to run until Step g of
component test sequence.
c. After 7 seconds the hot surface igniter is energized for 15
see., then of£
d. Blower motor operates on (ontinuous=FAN speed for 10
see.
e. Blower motor operates on HEAT speed £_r 10 sec.
£ Blower motor operates on COOL speed _br 10 sec.
g. Inducer motor stops.
5. Reconnect R lead to furnace contlol, remove tape fiom blower
door switch, and re=install blower door.
6. Operate furnace per instruction on outer door.
7. Verii}" ihmace shut down by lowering thermostat setting
below room temperature.
8. Verify7 that filrnace restarts by raising them_ostat setting above
roonl
temperature
Step 5--Adjustments
SET GAS INPUT RATE
Furnace gas input rate on rating plate is %r installations at altitudes
up to 2000 ft.
In the U.S.A., the input ratings for altitudes above 2000 ft must be
reduced by 2 percent fbr each 1000 ft above sea level.
In Canada, the input ratings must be derated by 5 percent for
altitudes between 2001 ft to 4500 ft above sea level.
Furnace input rate must be within ÷ 2 percent of input on [_urnace
rating plate adjusted for altitude
1. Determine natural gas orifice size and manifPld pressure for
correct input
a. Obtain average gas heat value (at installed altitude) fi'om
local gas supplier.
b. Obtain average gas specific gravity fiom local gas supplier
c. Verii}' f_m'nace model and size. Table 9 can only be used for
model 5gMXA fhmaces with rating plate heating inputs
(1000's Btuh) of 040 through 120. Table 10 can only be
used fbr model 58MXA fhmaces with a heating size of 140.
d. Find installation altitude in Table 9 or 10.
NOTE: For Canadian altitudes of 2001 to 4500 It, use L.SA
altitudes of 200! to 3000 ft in Table 9 or 10.
e. Find closest natural gas heat value and specific gravity in
Table 9 or 10.
£ Follow heat value and specific gravity lines to point of
intersection to find orifice size and manifbld pressure
settings fbr proper operation.
--€
42
EXAMPLE: (0-2000 fi altitude using Table 9)
Heating value 1050 Btuicu ft
Specific gravity 0.62
TherefPre: Orifice No 45 and
Manifold pressure 3 6-in. wc
* Furnace is shipped with No. 45 orifices In this
example all main burner orifices are the cmTect size
and do not need to be changed to obtain the proper
input rate.
Check and verify7 burner orifice size in fEmace. NEVER ASSL ME
ORIFI(E SIZE; ALWAYS CHECK AND VERIFY
2. Adjust mani_bld pressure to obtain input rate
NOTE: Manifold pressure must always be measured with burner
enclosure fiont REMOVED Gas meter must always be clocked
with burner enclosure flout INSTALLED.
a Remove burner enclosure fi'ont
b. Remove seal cap that conceals adjustment screw for gas
valve regulator. (See Fig. 57.)
c Jumper R and W thermostat connections on control to start
_/rnace,
d. Turn adjusting screw, cmmterclockwise (out) to decrease
manifold pressure or clockwise (in) to increase manifbld
pressure
NOTE: This furnace has been approved for a manifold pressure
of 3.2 in. wc to 3.S in. wc when installed at altitudes up to 2000 ft.
For altitudes above 2000 It, the manifold pressure can be adjusted
from 2.0 in. wc to 3.S in. we. If manifold pressure is outside this
range, change burner orifices to obtain pressure in this range.
UNIT DAMAGE HAZARD
Failm'e to fbllow this caution may result in reduced furnace
1ilk
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 mm_bered &ill bit of
con'ect size. Never re&i!l art orifice A bun'-flee and squarely
aligned orifice hole is essential for proper flame characteristics.
._ . ® u
UNIT DAMAGE HAZARD
Failure to %tlow this caution may result in component
damage due to flame impingement of burners and heat
exchangers.
DO NOT re&ill orifices. Improper &illing (burrs, out-o_=
round holes, etc.) can cause excessive burner noise and
misdirection of burner flames. (See Fig. 58.)
e. Replace gas valve regulator adjustment screw seal cap.
£ Replace burner enclosure fiont and verify adjusted gas
input rate using method outlined in item 3
g. Look through sight glass in bmner enclosure and check
burner flame Burner flame should be clear blue, almost
tlanspareat. (See Fig 590
h. Remove jumper fiom R and W
Verify natural gas input rate by clocking gas meter.