70
7-3.
Hydro Unit Control
2) Control at the time of heating heater operation
• Controlled Object: Backup heater, Booster heater
The backup heater control starts when 3 minutes has passed after the heating heater operation started.
The backup heater control increases, decreases, or maintains the number of heaters every 10 minutes (DN)
depending on the difference between the heating set temperature (TSC_F) and the heater outlet temperature
(THO). Note that when the heating set temperature (TSC_F) +2K is reached, the unit stops energizing the
heater.
HWT-**M3W-E model has the backup heater 1 of 3 kW only.
HWT-**T6W-E model has the backup heater 2 of 3 kW. (Total 6 kW)
Booster heater operation come only output signal. (Booster heater activate under heater only mode)
Related DN
2-3) Heater control at the time of defrosting
• Object to be controlled: Backup heater
When a defrosting operation starts during the heating heat
pump operation, the unit energizes a backup heater (3 kW)
according to the heater outlet temperature sensor (THO) and
the set temperature (TSC_F) as shown in Figure.
1) When the heater outlet temperature sensor (THO) drops to
the temperature of 2°C below the TSC_F-β, the backup
heater is energized.
β can be changed for energy saving.
Defrosting ends according to the usual heater control.
Related DN
2-4) Forcible heater energization
To prevent freeze, the unit energizes or stops energizing a backup heater (3 kW) regardless of the unit status, not
operated or in operation.
• Object to be controlled: Backup heater
1) Energization start condition: TWO < 4 or TWI < 4 or THO < 4
2) Energization stop condition: TWO ≥ 5 and TWI ≥ 5 and THO ≥ 5
Defrosting ends according to the usual heater control.
Item Operation flow and applicable data, etc.
70
TSC_F-0
TSC_F-2
TSC_F+2
THO
E zone
D zone
C zone
B zone
A zone
Diff: 2K
Diff: 2K
Diff: 2K
Abnormality detection (A02 displayed)
Heater off
KEEP
Heater output down every
5, 10, 15, or 20 minutes
Heater output up every
10, 20, 30, or 40 minutes
Status Heater ON/OFF
Heater 1 Backup heater 3 kW = ON
Heater 2 Backup heater 6 kW = ON
Heater 3 Backup heater 9 kW = ON
Heater 4 Heater 3 + Booster heater
DN Setting item Default Setting available range
20 Hot water supply heat pump start temperature 38°C 20 - 45°C
21 Hot water supply heat pump stop temperature 52°C 40 - 65°C
33 Heater control of down time 1:10 min 0: 5 min 2: 15 min 3: 20 min
34 Heater control of up time 0:10 min 1: 20 min 2: 30 min 3: 40 min
Heater OFF
Heater ON
Diff: 2K
Status Heater ON/OFF
Heater 1 Backup heater 3 kW = ON
DN Setting item Default Setting available range
B9
β: 0 = 0K, ..., 4 = 40K
Recommendation: β = 2 (20K)
0K 0K - 40K
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