Carrier 58PAV - Manual (Page 13)

3. Continuous blower mode
When the R-G circuit is made, the blower motor will
operate on heating speed. During a call for heat, the
blower will stop, allowing the furnace heat exchangers
to heat up more quickly.
The blower will revert to continuous operation after the
heating cycle is completed.
When the thermostat “calls for cooling,” the blower
wiU operate on cooling speed. When the thermostat is
satisfied, the blower wiU operate an additional 90 sec­
onds before reverting back to continuous operation on
heating speed.
4. Heat pump mode
When instaUed with a heat pump, the furnace control
automaticaUy changes the timing sequence to avoid
long blower off time during demand defrost cycles.
When the W-Y or W-Y-G thermostat inputs are
received together, the control wiU change the blower to
heating speed or start the blower if it was off, and
begin a heating cycle. The blower wiU remain on until
the end of the purge period, then shut off until the end
of the ignition warm up and trial for ignition periods (a
total of 24 seconds). The blower wUl then come back on
at heating speed.
When the W input signal disappears, the control wiU
begin the normal inducer post-purge period and the
blower wUl change to cooling speed after a one second
delay. If the W-Y-G signals should disappear together,
the blower wiU remain on for the selected heating
blower off delay period, and the inducer wUl go through
its normal post-pm-ge period. If the W-Y inputs should
disappear, leaving the G signal input, the control wUl
go into continuous blower and the inducer wiU remain
on for the normal post-purge period.
While in heat pump mode, the control will use only the
17 second ignition warm-up period, and will not use the
45 second period at all. The control wUl initiate a 90
second blower only on delay before starting another
heat pump cycle, if there is a power interruption. Any
time the control senses false flame, the control wUl lock
out of the heating mode. This occurs because the con­
trol cannot sense the W input due to the false flame
signal, and as a result sees only the Y input and goes
into cooling mode blower off delay. AU other control
functions remain in standard format.
C. Startup Procedures
1. Self test—The furnace features a self-test system to
help diagnose a system problem in the case of a compo­
nent faUure. Two test pins (ST-1 and ST-2) are located
in the lower left-hand corner of the control board as
shown in Fig. 9. To initiate the self-test procedure,
momentarUy short across the two pins.
NOTE: The self-test feature wUl not operate if the con­
trol board is receiving any thermostat signals.
The self-test sequence is as foUows:
a. The furnace control wUl check itself and then oper­
ate the inducer motor for 10 seconds, then off.
b. The hot surface ignitor is then energized for 15 sec­
onds, then off.
c. The humidifier relay is then energized for 10 sec­
onds, then off.
d. The blower motor wUl operate on cooling speed for
10 seconds, then off.
e. The blower motor wUl operate on heating speed for
10 seconds, then off.
2. Purge gas lines—After aU connections have been made,
purge the lines and check for leaks.
A WARNING
Never purge a line into a combustion chamber. Never
use matches, candles, flame or other sources of ignition
for the purpose of checking leakage. Use a soap-and-
water solution to check for leakage. A faUure to foUow
this warning can cause a fire, explosion, personal
injury, or death.
3. To operate furnace, foUow procedures on operating
instructions label attached to furnace.
4. With furnace operating, set thermostat below room
temperature and observe that furnace goes off. Set
thermostat above room temperature and observe that
furnace restarts.
D. Adjustments
1. Set gas input rate.
There are two methods of adjusting the gas input rate.
The preferred method is by using Table 15 and step a.
The second method is by clocking the gas meter and
step b.
The gas valve regulator has been nominaUy-set at 3.5
ins. wc for natural gas. When adjusting input rate, do
not set manifold pressure above 3.8 or below 3.2 ins.
wc.
a. Check gas input rate using Table 15.
(1.) Obtain average yearly heat value for local gas
supply.
(2.) Obtain average yearly specific gravity for local
gas supply.
(3.) Verify furnace model. Table 15 can only be used
for Model 58PAV Furnaces.
(4.) Check and verify orifice size in furnace.
NEVER ASSUME THE ORIFICE SIZE,
ALWAYS CHECK AND VERIFY.
(5.) Find natural gas heat value and specific gravity
in Table 15.
(6.) FoUow heat value and specific gravity fines to
point of intersection. Find orifice size and mani­
fold pressure settings for proper operation at
given natural gas conditions.
EXAMPLE: '
Heat value 1070 Btu/cu ft
Specific gravity 0.58
Therefore; Orifice No. 44*
Manifold pressure 3.3 ins. wc
*The furnace is shipped with No. 43 orifices. Therefore, in
this example aU main burner orifices must be changed and
niamfold pressure must be adjusted.
(7.) Proceed to step c to adjust manifold pressure.
b. Check gas input rate by clocking gas meter.
(1.) Obtain average yearly heat value for local gas
supply.
(2.) Check and verify orifice size in furnace.
NEVER ASSUME THE ORIFICE SIZE,
ALWAYS CHECK AND VERIFY.
A CAUTION
DO NOT redrill burner orifices. Improper drilling
(burrs, out of round, etc.) can cause excessive burner
operating noise and misdirection of burner flames. This
could result in flame impingment on burners and heat
exchanger surfaces, leading to potential failures.
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