Hitachi RWM-(H)FSN3E, Service Manual

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5 Control system
SMGB0070 rev. 1 - 08/2011
149
5

Use of electric heater
When using Heater, unit normally operates in heat pump, and the heater supplies the extra heating necessary.
Heater till certain extreme outdoor temperature and Boiler will only operate when temperature is too low for Heat Pump
and Heater.
- Heater and boiler bivalent point
Heat Pump and Heater enabled if:
Š
Ambient Temperature (Bivalent outdoor temperature for Heater) (5-006)
Heat Pump and Heater disabled and Boiler enabled if:
Š
Ambient Temperature (Bivalent outdoor temperature for Boiler) (6-007)
Ta
20 [
5-006
]
Heat Pump
only
Only
Boiler
Heat Demand
Heat pum
p capacity
Heater
Heat Pump
[
6-007
] -20
Heat pump capacity
Heat pump
Heat pump
only
Only
Boiler
Heat Demand
Heater
-20
20 [ 5-006 ]
[ 6-007 ]
Text (ºC)
CAP (kW)
N O T E
• Boiler operation is only for bivalent system (alternating operation, parallel connected).
• In the H Boiler configuration, system control sets Boiler outdoor bivalent point at 5ºC below Heater
outdoor bivalent point. It will auto-increase (5-006) in order to maintain the 5ºC difference.