Dometic CapTouch Manuel D'installation page 5

5.1 Understanding the heating and cooling cycles
The heating and cooling cycles operate differently depending on the system installed.
This section describes the possible cycles.
5.1.1 Normal heating or cooling cycle
AUTOMATIC mode
Heating and cooling are supplied as required to meet the cabin temperature set point.
1. The system starts a cooling cycle once the cabin temperature exceeds the temper-
ature set point by 2 °F (1 °C) and starts a heating cycle once the cabin temperature
falls below the temperature set point by 2 °F (1 °C). The system continues the cycle
until the cabin temperature equals the set point.
2. During a cycle, the cabin temperature must drop below the set point by at least 4 °F
(2 °C) before the system switches from cooling to heating or exceed the set point
by at least 4 °F (2 °C) before the system switches from heating to cooling. This be-
havior prevents small temperature overshoots from causing the system to switch
between heating and cooling when it is not necessary.
Cool mode
It supplies cooling only and HEAT mode supplies heating only.
1. The cabin temperature for either mode is maintained within 2 °F (1 °C) of the set
point by default.
2. When the heating or cooling set point is satisfied, the compressor cycles OFF and
the fan returns to low speed.
Manual Fan Mode
The fan speed remains constant.
5.1.2 Chilled-Water system operation (CW systems only)
In CW systems, the water valve does not open unless the water temperature is adequate
to heat or cool the cabin. The adequate heating or cooling water temperature is
defined by the water temperature differential setting in the control parameters. Refer to
"Selecting a Parameter".
• Tap and hold Fan and Up simultaneously for three seconds, to view the current
water temperature.
• Refer to "Using the Control Display Panel". The fan remains on low speed until the
adequate water temperature is available.
NOTE To give heat when the required water temperature is not avail-
able, install the optional auxiliary electric heater, and program parame-
ter P-28. Refer to "Programming the
5.1.3 Reversing-valve operation (DX systems only)
COOL mode or HEAT mode is determined by the position of the reversing valve. The
reversing valve is programmed to automatically toggle in these situations:
• When the system is running and an opposite cycle is needed to maintain the tem-
perature, the reversing valve will toggle to the opposite position to start the oppo-
site cycle and reduce the starting surge of the compressor.
• When a cooling or heating cycle is initiated after the system has been OFF for less
than five minutes.
• When a cycle is interrupted by changing the display mode to OFF or changing the
set point from the display panel.
• To reduce reversing-valve noise, unnecessary valve toggling is limited by default.
Program the minimum compressor staging delay (parameter P-3) to five minutes
or greater, to end valve toggling. Refer to
NOTE When the system is powered up, a power-on-reset always initiates a
valve toggle.
5.1.4 De-icing cycle (DX systems only)
DX systems have a de-icing cycle option to prevent ice buildup on the evaporator coil
during extended periods of cooling operation. Installation variables, such as grille sizes,
Control".
"Programming the Control".
length of ducting, insulation, and ambient temperatures, decide the runtime required to
achieve the set point.
Factors that substantially increase the runtime include operating the system with hatches
and doors open and programming an unrealistic set point e.g. 65 °F (18.33 °C). Such
situations can cause the evaporator to form ice on warm humid days.
De-icing is accomplished by closely monitoring the room air temperature in 10 min inter-
vals during a cooling cycle. Depending on the parameter value and the change in room
temperature during these monitoring intervals, the control performs various actions to
prevent ice from forming or to melt ice that has already formed. This is accomplished
by short compressor shutdown periods combined with a one-speed increase in the fan
speed, and by periodic HEAT mode cycles with the fan turned off.
The de-icing cycle algorithm initiates periodic compressor shutdowns every 10 min if
the inside temperature is at or below 69 °F (20.56 °C). The lower the temperature, the
longer the compressor shutdown will last. In addition, the de-icing cycle algorithm will
perform brief reverse cycle runs (with the fan purposely turned off) if the cooling cycle
runs for 40 min without any cooling progress or if the cooling cycle runs for more than
60 min, regardless of cooling progress.
The parameter setting for the de-icing feature depends on whether you are using the
optional inside air temperature sensor or the display built-in temperature sensor. Instal-
lation of an optional inside air temperature sensor (located in the return air path) greatly
increases the effectiveness of the de-icing feature, and this option should be considered
whenever the display sensor cannot read the room temperature accurately.
For more details on parameter settings and navigation options, refer to
meter" and see full manual for "Navigation
5.2 Choosing the control operation
The four Mode indicators represent the different modes of the control: COOL,
DEHUMIDIFICATION, HEAT, and AUX HEAT. Refer to
for more detail on mode operation.
1. Tap the Mode icon to select a mode.
Refer to"Available Modes and Options for
Display icons illuminate to indicate the selected mode.
The display locks into the last mode selected after five seconds of inactivity, then dis-
plays the room temperature. The selected mode LED remains lit.
After 10 seconds of inactivity, the display shows the room temperature and enters the
IDLE state.
OFF displays on the screen to indicate the OFF state.
When the display is making a call for heating, cooling, aux heat, or humidity, the ap-
propriate Mode indicator blinks for two seconds ON and two seconds OFF.
2. Tap any icon to wake up the control from the OFF or IDLE state.
3. Tap and hold the Mode icon for three seconds to start a SLEEP state.
The display goes dark.
Normal operation continues.
4. Tap and hold the Mode icon for three more seconds to wake up the control.
5.2.1 Available modes and options for operation
Icon Mode and Function
The COOL mode icon illuminates when the COOL mode is se-
lected or when the unit is in an AUTOMATIC mode cooling cy-
cle. Only the cooling system operates. If the ambient tempera-
ture drops below the set point, the system will not automatically
switch to the HEAT mode.
"Selecting a Para
Tree".
"Using the Control Display
Fig.  on page 3
Operation".
EN
Panel"
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