Control Specification SiUS091601E43 Functions and Control3.3 Controls at Mode Changing / Start-up3.3.1 Preheating ControlOutline The inverter operation in open phase starts with the conditions of the outdoor temperature, thedischarge pipe temperature, the radiation fin temperature and the preheating command from theindoor unit.Detail Outdoor temperature ≥ –2.5°C (27.5°F) → Control A (preheating for normal state)Outdoor temperature < –2.5°C (27.5°F) → Control B (preheating of increased capacity)Control A ON conditionDischarge pipe temperature < 0°C (32.0°F)Radiation fin temperature < 85°C (185°F) OFF conditionDischarge pipe temperature > 2°C (35.6°F)Radiation fin temperature ≥ 90°C (194°F)Control B ON conditionDischarge pipe temperature < 10°C (50.0°F)Radiation fin temperature < 85°C (185°F) OFF conditionDischarge pipe temperature > 12°C (53.6°F)Radiation fin temperature ≥ 90°C (194°F)3.3.2 Four Way Valve SwitchingOutline The four way valve coil is energized / not energized depending on the operation mode. (Heating:ON, Cooling / Dry / Defrost: OFF)In order to eliminate the switching sound as the four way valve coil switches from ON to OFF whenthe heating is stopped, the OFF delay switch of the four way valve is carried out.Detail OFF delay switch of four way valveThe four way valve coil is energized for 160 seconds after the operation is stopped.
