Two-Stage Thermostat And Two-Stage Heating; Cooling Mode; Single-Speed Cooling; Single-Stage Thermostat And Two-Speed Cooling (Adaptive Mode) - Carrier 58MVP Installation, Start-Up, And Operating Instructions Manual

5,llnducer Speed C hange=If thecycle starts i n tow-heat,
the
furnace contlol CPU reduces the inducer speed slightly after
flame sense. If cycle starts in high=heat, the fi_rnace control
CPU increases the inducer speed 15 seconds after flame sense.
The reduction in speed in tow-heat is to optimize combustion
_br maximam efficiency.
6. Blower-On delay=If the burner flame is proven, the
blower=ON delay fbr low=heat and high-heat are as follows:
Low-heat-60 seconds after the gas valve GV-M is opened, the
BLWM is turned ON at tow=heat airflow.
High-heat-35 seconds aker gas valve GV=M is opened, the
BLWM is tamed ON at high-heat airflow.
Sin-mltaneously, the humidifier terminal HUM and electronic
air cleaner tem_inal EAC-1 are energized and remain ener-
gized throughout the heating cycle.
7. Switching Front Low- To High- Heat- If the fllmace contlol
(PU switches fi'om tow=heat to high=heat, the t:urnace control
(PU will de=energize the the high=heat pressure switch relay
HPSR to close the NC contact and slowly increase the inducer
motor speed until tl_e high-heat pressure switch HPS closes.
When the high-heat pressure switch HPS closes, the high=heat
gas valve solenoid GV=HI is energized and the indacer motor
RPM is noted by the furnace control CPU. The RPM is used
to evaluate vent system resistance. This evaluation is then
used to determine the required RPM necessary to operate the
inducer motor in high-heat mode. The blower motor BLWM
will transition to high-heat airflow five seconds aker the
furnace control CPU switches fiom low-heat to high=heat.
8. Switching Front High- To Low- Heat-The fl/rnace control
(PU will not switch from high-heat to low-heat while the
thermostat R=to-W circuit is closed when using a single=stage
thermostat.
9. Blower-Off dday- When the thermostat is satisfied, the R to
W circuit is opened, de-energizing the gas valve GV-M,
stopping gas flow to the burners, and de=energizing the
humidifier terminal HUM. The inducer motor IDM will
remain energized for a 15=second post-purge period. The
blower motor BLWM and air cleaner tem_inal EAC=I will
remain energized at low=heat airflow or transition to low=heat
airflow for 90, 120, 150, or 180 seconds (depending on
selection at blower=OFF delay switches). The fi_rnace control
(PU is iSctoLy=set for a 120=second blower-OFF delay.
TWO-STAGE THERMOSTAT AND TWO=STAGE HEATING
See Fig. 60 _br themlostat connections
NOTE: In this mode, the low-heat only switch SWI=2 must be
ON to select the low-heat only operation mode in response to
closing the thermostat R-to=W1 circuit. Closing the thermostat
R-to=Wl-and=W2 circuits always causes high=heat operation, re=
gardless of the setting of the low=heat-only switch.
The wall thermostat "calls for heat", closing the R to W1 circuit for
low-heat or closing the R to Wl=and-W2 circuits for high-heat.
The furnace control per_brms a self-check and verifies the low=
heat and high=heat pressure switch contacts LPS and HPS are
open.
The start=up and shutdown functions and delays described in item
1 above apply to 2=stage heating mode as well, except for
switching fi'om low= to high=heat and vice versa.
1. Switching From Low- To High- Heat-If the thermostat R to
W1 circuit is closed and the R to W2 circuit closes, the [:urnace
contloi CPU will de=energize the high=heat pressure switch
relay HPSR to close the NC contact and slowly increase the
inducer motor speed until the high-heat pressure switch HPS
closes. When the high=heat pressure switch closes, the high=
4O
heat gas valve solenoid GV=HI is energized and the inducer
motor RPM is noted by the fhrnace conhol CPU The RPM is
used to evaluate vent system resistance This evaluation is
then used to detem_ine the required RPM necessary to operate
the inducer motor in high-heat mode. The blower motor
BLWM will transition to high=heat airflow five seconds after
the R to W2 circuit closes
S_itehing From High- To Low- Heat= If the thermostat R to
W2 circuit opens, and the R to W1 circuit remains closed, the
fhmace contIol CPU will energize the high=heat pressure
switch relay HPSR to open the NC contact and slowly
decrease the inducer motor speed to the required low-heat
RPM. When the high=heat pressure switch HPS opens, the
high=heat gas valve solenoid GV=HI is de-energized. When
the inducer motor IDM reduces pressure sufficiently, the
high=heat pressure switch HPS will open. The gas valve
solenoid GV=M will remain energized as tong as the low-heat
pressure switch LPS remains closed. The blower motor
BLWM will transition to tow=heat airflow five seconds after
the R to W2 circuit opens.
COOLING MODE
The thermostat "calls for cooling"
1. Single-Speed Cooling
(See Fig. 28 _br them_ostat connections.)
The themaostat closes R-to=G=and-Y circuits. The R=m-Y
circuit starts the outdoor unit, and R=to-G-and=YiY2 circuits
start the flu'nace blower motor BLWM on cooling airflow.
(ooling airflow is based on the AiC selection shown in Fig.
50.
The electronic air cleaner terminal EA(-1 is energized with
115-v when blower motor BLWM is operating
When the thermostat is satisfied, the R=to-G-and=Y circuits are
opened. The outdoor unit will stop, and furnace blower motor
BLWM will continue operating at cooling airflow for an
additional 90 sec. Jumper Y/Y2 to DHUM to reduce the
cooling off-delay to 5 seconds (See Fig. 32)
2. Single-Stage T]hermostat and Two-Speed (ooling (Adap-
tive Mode)
(See Fig. 6I fbr them_ostat connections.)
This fhmace can operate a two=speed cooling unit with a
single=stage thermostat because the fln'nace control CPU
includes a programmed adaptive sequence of controlled op-
eration, which selects tow=cooling or high=cooling operation.
This selection is based upon the stored histoQ- of the length of
previous cooling period of the single-stage thet_nostat.
NOTE: The air conditioning relay disable juniper A(RDJ must
be connected to enable the adaptive cooling mode in response to a
call for cooling. (See Fig. 320 When in place the fl/rnace contlol
CPU can mm on the air conditioning relay ACR to energize the
Y/Y2 terminal and switch the outdoor unit to high=cooling.
The fl/rnace control (PU can start up the cooling unit in either
low- or high=cooling. If starting up in low-cooling, the fl_rnace
control CPU determines the low-cooling on-time (from 0 to 20
minutes) which is pem_itted be£_re switching to high=cooling.
If the power is interrupted, the stored history is erased and the
flul_ace control CPU wilt select tow=cooling _br up to 20
mirmtes and then energize the air conditioning relay ACR to
energize the Y/Y2 terminal and switch the outdoor unit to
high=cooling, as long as the themlostat continues to call for
cooling. Subsequent selection is based on stored histow of the
thermostat cycle times