76
7-3.
Hydro Unit Control
7) Room temperature control with the thermostat
You can install a commercially available thermostat to control room temperature.
7-1) Installing the room temperature thermostat
• Connect its connection cable to CN21 port on the PC board (MCC-1755) of the hydro unit.
• Thermostat for heating: Connect the input between the terminals (1) and (5).
Thermostat for cooling: Connect the input between the terminals (2) and (5).
• Place to install (inside a room): At the height of 120 cm - 180 cm on a wall
Opposite to the radiator or fan coil installed
No assignment when floor heating is used on the room.
Optional inputs to Hydro Unit
This unit has eight input ports. 2 ports of them are selectable by DN. Table2 shows the selectable input functions and
default settings.
Non-voltage contacts
7-2) Room temperature thermostat control setting
• Setting of DN_6B3 = “1” (Default “0”)
I/P1 & I/P2: Room thermostat input
• Setting of DN_6B3 = “1”
• Non-voltage contacts
Thermostat operation
7-3)Heating thermostat operation
When the heating thermostat does not reach the assigned temperature (the circuit between (1) and (5) is closed),
heating starts under the setting that water temperature for heating is 40°C (DN_9D). If the heating thermostat has not
reached the assigned temperature 30 minutes after heating had started, the water temperature setting is turned up 1
degree, and the same action will be repeated every 30 minutes until the thermostat reaches the assigned temperature.
The backup heater and booster heater are controlled in the same way as in the normal HP operation.
When the heating thermostat reaches the assigned temperature (the circuit between (1) and (5) is open), the heat
pump shifts to the “thermostat off” operation. During the operation, the water temperature setting is turned down by 1
degree every 30 minutes. The backup heater and booster heater are tuned off as the heat pump shifts to the
“thermostat off” operation.
Item Operation flow and applicable data, etc.
MCC-1755
I/P 4
common
line
CN21
1
2
3
4
5
6
7
8
9
10
Hydro Unit sub PCB
common
line
I/P 3
I/P 2
I/P 1
I/P 8
I/P 7
I/P 6
I/P 5
Locally procured
Input items (Default setting)
I/P 1 Room thermostat input for heating
I/P 2 Room thermostat input for cooling
I/P 3 Hot water tank thermostat input
I/P 4 Heating/cooling mode switching input
I/P 5 Heating/cooling operation ON/OFF
I/P 6 Hot water operation ON/OFF
I/P 7 (DN_B6) 0: Emergency shutdown input
I/P 8 (DN_B6) 0: None
CN21
Heating Cooling
Reach Not reach Reach Not reach
1-5 (I/P1) open close - -
2-5 (I/P2) - - close open
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