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Table 5 — DIP Switch Block S2 —
Accessory 1 Relay Options
LEGEND
NOTE: All other DIP switch combinations are invalid.
Table 6 — DIP Switch Block S2 —
Accessory 2 Relay Options
LEGEND
NOTE: All other switch combinations are invalid.
Auto Dehumidification Mode or High Fan Mode —Switch7
provides selection of auto dehumidification fan mode or high
fan mode. In auto dehumidification fan mode the fan speed
relay will remain off during cooling stage 2 if terminal H is
active. In high fan mode, the fan enable and fan speed relays
will turn on when terminal H is active. Set the switch to ON for
auto dehumidification fan mode or to OFF for high fan mode.
Switch 8
— Not used.
D Control Accessory Relay Configurations —
The following accessory relay settings are applicable for both
D controls only:
CYCLE WITH FAN — In this configuration, the relay will be
ON any time the Fan Enable relay is on.
CYCLE WITH COMPRESSOR — In this configuration, the
relay will be ON any time the Compressor relay is on.
DIGITAL NIGHT SET BACK (NSB) — In this configura-
tion, the relay will be ON if the NSB input is connected to
ground C.
NOTE: If there are no relays configured for digital NSB, then
the NSB and OVR inputs are automatically configured for
mechanical operation.
MECHANICAL NIGHT SET BACK — When NSB input is
connected to ground C, all thermostat inputs are ignored. A
thermostat set back heating call will then be connected to the
OVR input. If OVR input becomes active, then the D control
will enter Night Low Limit (NLL) staged heating mode. The
NLL staged heating mode will then provide heating during the
NSB period.
Water Valve (Slow Opening) — If relay is config-
ured for Water Valve (slow opening), the relay will start 60 sec-
onds prior to starting compressor relay.
Outdoor-Air Damper (OAD) — If relay is configured
for OAD, the relay will normally be ON any time the Fan
Enable relay is energized. The relay will not start for 30 min-
utes following a return to normal mode from NSB, when NSB
is no longer connected to ground C. After 30 minutes, the relay
will start if the Fan Enable is set to ON.
START-UP
Use the procedure outlined below to initiate proper unit
start-up.
NOTE: This equipment is designed for indoor installation only.
Operating Limits
ENVIRONMENT — This equipment is designed for indoor
installation ONLY. Extreme variations in temperature, humidi-
ty and corrosive water or air will adversely affect the unit per-
formance, reliability and service life.
POWER SUPPLY — A voltage variation of ± 10% of name-
plate utilization voltage is acceptable.
UNIT STARTING CONDITIONS — Depending on the mod-
el, units start and operate in an ambient temperature of 7.2 C
with entering air temperature at 4.4 C or 10 C, entering water
temperature at –6.7 C or 10 C and with both air and water at the
flow rates used.
NOTE: These operating limits are not normal or continuous
operating conditions. Assume that such a start-up is for the
purpose of bringing the building space up to occupancy tem-
perature. See Table 7 for operating limits.
1. Restore power to system.
2. Turn thermostat fan position to ON. Blower should start.
3. Balance airflow at registers.
4. Adjust all valves to the full open position and turn on the
line power to all heat pump units.
5. Operate unit in the cooling cycle. Refer to Table 7 for unit
operating limits.
NOTE: Three factors determine the operating limits of a unit:
(1) entering air temperature, (2) water temperature and (3)
ambient temperature. Whenever any of these factors are at a
minimum or maximum level, the other two factors must be at a
normal level to ensure proper unit operation. See Table 7.
Table 7 — Operating Limits — 50RHE Units
LEGEND
NOTE: Value in heating column is dry bulb only. Any wet bulb read-
ing is acceptable.
ACCESSORY 1
RELAY OPTIONS
DIP SWITCH POSITION
123
Cycle with Fan On On On
Digital NSB Off On On
Water Valve — Slow Opening On Off On
OAD On On Off
NSB — Night Setback
OAD — Outdoor-Air Damper
ACCESSORY 2
RELAY OPTIONS
DIP SWITCH POSITION
456
Cycle with Fan On On On
Digital NSB Off On On
Water Valve — Slow Opening On Off On
OAD On On Off
NSB — Night Setback
OAD — Outdoor-Air Damper
To avoid equipment damage, DO NOT leave system filled
in a building without heat during the winter unless anti-
freeze is added to system water. Condenser coils never
fully drain by themselves and will freeze unless winterized
with antifreeze.
When the disconnect switch is closed, high voltage is
present in some areas of the electrical panel. Exercise
caution when working with the energized equipment.
AIR LIMITS COOLING (C) HEATING (C)
Min. Ambient Air 7.2 7.2
Rated Ambient Air 26.7 21.1
Max. Ambient Air 37.8 29.4
Min. Entering Air 10 4.4
Rated Entering Air db/wb 27/19 20/15
Max. Entering Air db/wb 43.3/28.3 27
WATER LIMITS
Min. Entering Water –1.1 –6.7
Normal Entering Water 10 to 32 –1.1 to 15.6
db — Dry Bulb
wb — Wet Bulb