10
W A T E R - S O U R C E H E A T P U M P S
ATA11U03
R e v. : 0 9 / 1 6 / 1 3
Timers
— There are several timers which influence the
thermostat’s operation that are listed below. If any of the
timers is preventing the equipment from turning on, the
“on” icon will flash.
Five-Minute Compressor Timeguard
— This timer
prevents the Y1 output from turning on unless it has been
off for 5 minutes. (Option 07 set to OF)
After a power cycle, a randomized delay will be added
to end of the timeguard timer to prevent multiple units
from hitting the power grid all at the same time. The
randomization timer will be between zero and five
minutes. If a demand exists, compressor outputs will
energize between 5 and 10 minutes after the power
cycle. It can be defeated by simultaneously pressing the
fan and up keys.
Minimum On Timer
— Once the equipment has been
turned on, it must remain on for 3 minutes. A change in
mode or set point will cancel this timer.
Cycle Timer
— The number of equipment cycles per hour
is determined by configuration Option 16. Based on the
selection of 4, 6 or 8 cycles per hour, this timer is set to
15, 10 or 8 minutes. This much time must elapse from the
start of one cycle before another cycle can start, imposing
the cycles per hour limits. It can be defeated for one cycle
by simultaneously pressing the fan and up keys.
TROUBLESHOOTING
There are three system error messages that may appear
on the thermostat screen indicating a problem with
the thermostat’s operation. See text below for possible
system error messages and their meaning.
Space Temperature Sensor Failure
— If the room
temperature sensor fails, the temperature display will
show “--” (two dashes). If the space temperature is
the average of both the local and remote sensors (as
configured in Option 5), and one of the sensors fails, the
thermostat provides control to the valid sensor only. The
display will alternate every 10 seconds between “--” for
the invalid sensor and the reading from the valid sensor.
Memory Failure
— If there is an internal memory failure,
the temperature display will show “E4,” the thermostat
needs to be replaced.
WIRING DIAGRAMS
System wiring diagram is shown for typical ClimateMaster
heat pump unit. See Fig. 7.
O is Energized for cooling
G is low speed fan
G2 is hi speed fan
Figure 7: Typical Wiring Diagram - Heat Pump
Rc
Rh
W
C
G
G2
R
W OR W1
C
G
H (DXM ONLY)
O
Y or Y1
NOTE 1
NOTE 2
S2
S1
O
Y1
THERMOSTAT
HEAT PUMP
CXM/DXM
HEAT PUMP
REMOTE
SENSOR
(Optional)
