Carrier 50PG20-28 Controls, Start-Up, Operation, Service And Troubleshooting Instructions page 48

REHEAT MODE SELECTION PROCESS Selection ofthe
reheat mode foreach r efi-igerant circuit i sdetermined fiomthe
space h umidity ( tiomRHsensor or switch input) a ndthe
circuit cooling d elnand (fiom space temperature sensor orther-
mostat input). Table 4 2shows theconesponding circuit m ode
and output status forthe different demand combinations.
Figure 9 shows t hevalvelocations of Humidi-MiZer
TM
equipped units. Units with multiple circuits can operate with a
combination of Reheat 1and Reheat2 circuits, as determined by
the amount of space cooling demand. See Appendix B for
complete tables of unit operation response to thermostat and
humidity inputs.
REHEAT MODE DIAGNOSTIC HELP The status of
reheat mode sensor inputs may be viewed within the display
Inputs menu. The status of reheat mode outputs may be viewed
within the display Outputs or Run Status--yCOOL menus.
Additional diagnostic help, including status of circuit reheat
temperature limit lockouts may be viewed within the
Humidi-MiZer sub-menu of the cooling mode diagnostic table
at Operating Modes _'OOL --yHMZR.
The Sel_giceTest mode may be used to force the system to
operate in various stages of Reheatl oi Reheat2 mode, or to
independently operate the reheat valve control outputs.
The following forced operating states are changed oi added
to the available sel_qce test operation for a Hmnidi-MiZer
equipped unit:
Setwice Test-+COOL-+CMP.A (Cool A Test) A value of
On wilt turn on circuit A in Normal Cooling mode.
Setwice Test-+COOL-+CMP.B (Cool B Test) A value of
On will turn on circuits A and B in Normal Cooling mode.
Setwice Test-+COOL-+CMP. C (Coot C Test) Not used.
Service Test-+HMZR-+RH1.A (Reheat1 A Test) A value
of On wilt turn on circuit A in Reheat 1mode.
Setwice Test-+HMZR-+RH1.B (Reheatl B Test) A value
of On will turn on circuits A and B in Reheat 1 mode.
Setwice Test-+HMZR-+RH1.C(Reheatl C Test) Not used.
Setwice Test-+HMZR-+RH2.A (Reheat2 A Test) A value
of On will turn on circuit A in Reheat2 mode.
Setwice Test-+HMZR-+RH2.B (Reheat2 B,C Test) A value
of On will turn on circuits A and B in Reheat2 mode.
Service Test-+HMZR-+CRC (Cool-Reheatl Valve Test)
A value of On will turn on the CRC relay. This will energize
RH1.A and RH1.B.
Set'vice Test-+HMZR-+RHV.A (Reheat2 Valve A Test)
A value of On will turn on the RH2.A valve.
Setwice Test-+HMZR-+RHV.B (Reheat2 _alve B,C
Test) A value of On will turn on the RH2.B valve.
Service Test-+Fans-+OFC.1 (Outdoor Fan 1 Test) Turn on
OFC1, providing power to the Motonnaster,¢9 controller.
Outdoor fans 1 and 4 will operate under the control of the
Motonnaster controller.
R}!I A
I
RH2A
Fig. 9 -- Humidi-MiZer System Valve Locations
Service Test-+Fans-+OFC.2 (Outdoor Fan 2 Teso Turn on
OFC2. Outdoor fans 2, 3, 5, and 6 will operate.
Service Test-+Fans-+OFC.3 (Outdoor Fan 1 Test) Not
used.
Service Test-+INDP-+(L7t (Crankcase Heat Test) Not
used. Compressor crankcase heaters are wired directly to line
powe£
AIR BAFFLES The 48/50PG units with Humidi-MiZer
option are equipped with Motonnaster,¢9 control to maintain
adequate dischaNe pressalre for proper unit operation during
low ambient operation. This becomes especially c_-iticalin the
Reheat2 mode of operation. Wind could have a detiimental
effect depending on the orientation and the expected design
latent load of the space. If the unit is oriented with the vertical
condenser coil toward the prevailing wind, then the field-
fabricated wind baffles are required. If the unit is not oriented
as described above, but there is expected long operational
periods in the Reheat2 mode, then the field-fabricated wind
banes are recommended. See Fig. 10 for dimensions of the
field-fabricated wind baffles.
Table 42 -- Control Modes with Humidi-MiZer System
Output and Valve States versus Circuit Mode .x = Circuit A or B identifier
DEMAND AND MODE OUTPUTS VALVES
Circuit Circuit Cooling-Reheat Reheat2
Space Cooling Circuit Indoor Fan RHI,x Valve RH2.x Valve
Humidity Mode (IDF) Compressor Control Valve
Demand (CMP.x) (CRC)* (RH2.x) 3-way 2-way
-- --
No power OFF OFF OFF OFF Off Off (closed)
Low No Off Per ventilation OFF OFF OFF Off Off (closed)
control
Low Yes Coot ON ON OFF OFF Off Off (ctosed)
High Yes Reheat1 ON ON ON OFF On Off (closed)
High No Reheat2 ON ON ON ON On On (open)
*NOTE: One CRC state for all circuits per space humidity.
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