78
7-3.
Hydro Unit Control
8) Hot water cylinder thermostat control
Hot water can be supplied using an existing hot-water cylinder with a thermostat.
8-1) Installing the hot-water cylinder thermostat
• Connect its connection cable to CN21 port on the PC board (MCC-1755) of the hydro unit.
• Hot-water cylinder heating thermostat: Connect this thermostat between (3) and (5).
• Place to install the thermostat (hot-water cylinder): At a height of 30 to 50 cm from the base.
• Hot-water heater: A hot-water heater is required. (Without a hot-water heater, the hydro unit will not work.)
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
8-2) Setting the hot-water cylinder thermostat
I/P3: Hot water tank thermostat input
• This function is used with DN_6B2 is “1”, when the customer use the local hot water tank.
• Setting of DN_6B2 = “1”
• Non-voltage contacts
Open: Reached setting temperature
Close: Not reached setting temperature
8-3) Hot-water thermostat operation (hot-water supply operation only)
If hot water is used when the hot-water thermostat is at the assigned temperature (the circuit between (3) and (5) is
open), the hot-water heat pump starts with the hot-water thermostat closed.
After 120 minutes, the hot-water cylinder heater turns on, but the hot-water heat pump continues running until the
hot-water cylinder thermostat becomes open.
It should be noted, however, that the hot-water heat pump might stop if the water input temperature becomes high.
8-4) Hot-water thermostat operation (hot-water supply + heating operation)
If hot water is used when the hot-water thermostat is at the assigned temperature (the circuit between (3) and (5) is
open), the hot-water heat pump starts with the hot-water thermostat closed.
In 30 minutes, the hot-water heat pump stops. After that, only the hot-water cylinder heater is used to raise water
temperature.
The heat pump switches to heating operation. Unless the hot-water cylinder thermostat temperature rises, the hot-
water heat pump will never take over.
8-5) Hot-water thermostat operation (hot-water supply + cooling operation)
For automatic switching to hot-water supply plus cooling operation, DN_0F is required.
If hot water is used when the hot-water thermostat is at the assigned temperature (the circuit between (3) and (5) is
open), the hot-water heat pump starts with the hot-water thermostat closed.
In 30 minutes, the hot-water heat pump stops. After that, only the hot-water cylinder heater is used to raise water
temperature.
The heat pump switches to cooling operation. Unless the hot-water cylinder thermostat temperature rises, the hot-
water heat pump will never take over.
Related DN
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
DN Setting item Default Setting value
0F Hot water HP allowance while cooling + hot water supply 0: Not allow 1: Allow
73
Hot water tank heater start time of heat-pump while
operating
3: 120 min passed 0: 30 min passed
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