48
REHEAT MODE SELECTION PROCESS — Selection of the
reheat mode for each refrigerant circuit is determined from the
space humidity (from RH sensor or switch input) and the
circuit cooling demand (from space temperature sensor or ther-
mostat input). Table 42 shows the corresponding circuit mode
and output status for the different demand combinations.
Figure 9 shows the valve locations of Humidi-MiZer™
equipped units. Units with multiple circuits can operate with a
combination of Reheat1 and 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
→
COOL 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
→
COOL
→
HMZR.
The Service Test mode may be used to force the system to
operate in various stages of Reheat1 or Reheat2 mode, or to
independently operate the reheat valve control outputs.
The following forced operating states are changed or added
to the available service test operation for a Humidi-MiZer
equipped unit:
Service Test→COOL→CMP.A (Cool A Test) — A value of
On will turn on circuit A in Normal Cooling mode.
Service Test→COOL→CMP.B (Cool B Test) — A value of
On will turn on circuits A and B in Normal Cooling mode.
Service Test→COOL→CMP.C (Cool C Test) — Not used.
Service Test→HMZR→RH1.A (Reheat1 A Test) — A value
of On will turn on circuit A in Reheat1 mode.
Service Test→HMZR→RH1.B (Reheat1 B Test) — A value
of On will turn on circuits A and B in Reheat1 mode.
Service Test→HMZR→RH1.C (Reheat1 C Test) — Not used.
Service Test→HMZR→RH2.A (Reheat2 A Test) — A value
of On will turn on circuit A in Reheat2 mode.
Service 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-Reheat1 Valve Test) —
A value of On will turn on the CRC relay. This will energize
RH1.A and RH1.B.
Service Test→HMZR→RHV.A (Reheat2 Valve A Test) —
A value of On will turn on the RH2.A valve.
Service Test→HMZR→RHV.B (Reheat2 Valve 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 Motormaster® controller.
Outdoor fans 1 and 4 will operate under the control of the
Motormaster controller.
Service Test→Fans→OFC.2 (Outdoor Fan 2 Test) — 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→CCH (Crankcase Heat Test) — Not
used. Compressor crankcase heaters are wired directly to line
power.
AIR BAFFLES — The 48/50PG units with Humidi-MiZer
option are equipped with Motormaster® control to maintain
adequate discharge pressure for proper unit operation during
low ambient operation. This becomes especially critical in the
Reheat2 mode of operation. Wind could have a detrimental
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
baffles 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
*NOTE: One CRC state for all circuits per space humidity.
DEMAND AND MODE OUTPUTS
VALVES
Space
Humidity
Circuit
Cooling
Demand
Circuit
Mode
Indoor Fan
(IDF)
Circuit
Compressor
(CMP.x)
Cooling-Reheat
Control
(CRC)*
Reheat2
Valve
(RH2.x)
RH1.x Valve
3-way
RH2.x Valve
2-way
— — No power OFF OFF OFF OFF Off Off (closed)
Low No Off
Per ventilation
control
OFF OFF OFF Off Off (closed)
Low Yes Cool ON ON OFF OFF Off Off (closed)
High Yes Reheat1 ON ON ON OFF On Off (closed)
High No Reheat2 ON ON ON ON On On (open)
Fig. 9 — Humidi-MiZer System Valve Locations
a48-8225
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