Carrier SmartVu - Built-in DHW and Space Heating Control

36
6.6 - Built-in DHW and space heating control
61AF heat pumps are specially designed to optimise the operation
of heating installations that require hot-water production for
traditional heating (SHC) and domestic hot water (DHW)
requirements.
The SmartVu
TM
permits constant and automatic optimization
of the unit:
■ Control of a three-way directional on/o󰀨 valve based on the
heating or domestic hot water requirements (3-way valve used
to switch between Space Heating Control and Domestic Hot
Water). By default, the unit is operating in Space Heating mode.
■ Control of the electric heater stages can complement the heating
loop (1 to 4 electric heating stages). See section 6.7.2.
6.6.1 - Heating of domestic hot water mode
The three-way valve permits switching the heating capacity to a
heating circuit (fan coil units, radiators or oor heating), or to a
domestic hot water tank. If the unit is in domestic hot water
production mode, a “DHW” message is displayed on the user
interface next to the current operating mode.
The unit requests changeover to DHW mode provided that
both water tank conditions and unit conditions are met:
■ Water tank conditions
- “DHW Request Input” volt-free contact is closed or “DHW
Tank Temperature” is below “DHW Setpoint” AND
- The third timer program (schedule 3) is set to occupied (DHW
mode requested) and the anti-legionella program is not
requested (see section 6.13).
■ Unit conditions
- Summer mode is active (space heating is not required) OR
- Summer mode is NOT active and the minimum SHC operating
time and the maximum DHW operating time parameters allow
for that (service-congured parameters).
NOTE: Domestic Hot Water schedule can be activated
regardless of the current operating mode (Local/Remote/Net).
Based on the operating mode (SHC or DHW) the water setpoint
is adjusted:
- In heating mode, hsp1 and hsp2 are used. They can be
modied by user reset (see section 6.5.2).
- In domestic hot water production mode, DHW setpoint is
used. No setpoint reset is used.
The unit requests changeover to the heating mode if at least one
of the following conditions applies:
- The volt-free tank request contact is open.
- The maximum operating time for the DHW mode has elapsed.
- Time schedule 3 is in an unoccupied period (DHW mode not
requested).
If a mode change is requested while a compressor is operating, it
is stopped before the three-way valve changes to the new mode,
and then the unit is restarted.
6.6.2 - Anti-legionella
Water storage tanks where the water may stagnate for some time
could create the environment allowing for the growth of legionella
bacteria. To prevent the risk of legionella growth in the hot water
tank, the control performs the anti-legionella treatment which
means that water temperature is increased until it reaches the
Anti-Legionella setpoint (legionella bacteria do not survive in
temperature at 60°C).
The anti-legionella program can be activated automatically via the
schedule setting. To activate the anti-legionella program, the
installer should set the fourth timer program (schedule 4). The
water tank temperature is increased until the anti-legionella
setpoint [leg_sp] is reached or a 6-hour period has elapsed.
The program cannot be activated more than once within 6 hours.
For more information about setting the anti-legionella schedule,
see section 6.13.
6.6.3 - Summer mode
The Summer mode is used to control Domestic Hot Water mode.
When the Summer mode is active, space heating is not required,
and the unit can increase the water temperature in the water tank
in order to provide hot domestic water.
The Summer mode can be activated only when the outdoor air
temperature exceeds the predened Summer OAT threshold
(“Maximum OAT Threshold”).
To set Summer OAT threshold
1. Navigate to the Conguration menu.
2. Select Heat/Cool Cong (HCCONFIG).
3. Set Max Heating OAT Threshold [max_th].
Maximum Heating OAT Threshold [max_th]
-100 to 100°C 100°C
-148 to 212°F 212°F
The Summer mode will end when the outdoor air temperature
drops below the predened Summer OAT threshold - 2K, e.g. if the
Summer OAT threshold is set to 20°C, the Summer mode will end
as soon as the outdoor air temperature reaches the temperature
of 18°C.
NOTE: When the Maximum OAT Threshold parameter is set
to an unreachable value, e.g. 100°C, then the Summer mode
will be disabled.
6 - STANDARD CONTROL OPERATIONS AND OPTIONS