Protection Menu / 8.5 - ODU Heating Cable
Most outdoor air-conditioning units include a chassis heating cable used to defrost condensed water that drains to the bottom of the unit and flows out from there.
However, this heating cable is often switched on by the outdoor unit even when it is not necessary (typically it turns on below 0 °C and switches off above +2 °C), which unnecessarily increases electrical energy consumption. MiniHPC allows one of the outputs R1, R2, R4, or R5 to be used to control this heater according to configured criteria.
Please note that commissioning this function requires intervention inside the outdoor unit and routing a 2-wire cable that connects the outdoor unit’s heating element to a relay output on the MiniHPC.
Relays R1 and R4 are available only if DHW heating is not enabled in menu 3.1 DHW temperatures. Relay R2 is available only if auxiliary heating is not enabled in menu 1.5 Electric heater R2. Relay R5 is available if the 3-way valve is not switched during cooling, as configured in menu 2.5 3-way valve R5.
- 1. In series with the outdoor unit’s switching relay: In this case, the heating element will not be energized if the outdoor unit disables this heater. MiniHPC can only enable the heater together with activation by the outdoor unit. The disadvantage of this wiring is that if the outdoor unit disables the heater, MiniHPC cannot switch it on independently when needed. Some air conditioners in PID mode do not activate the heater at all, even when required. Therefore, the second wiring method is preferred.
- 2. Switching controlled by MiniHPC independently of the outdoor unit: The main advantage of this wiring is that it is completely independent of the outdoor unit’s switching relay, and the switching algorithm (or manual activation via the service menu) is handled exclusively by MiniHPC.
Example of the location of the connector labeled HEAT-B on the outdoor unit’s PCB. This specific example is taken from the service manual of the Gree Clivia air conditioner.
In most cases, this is a green connector with orange wires.
Series connection with the outdoor unit’s switching relay
At the connector labeled HEAT-B, one of the wires supplying the outdoor unit heating element is cut. A suitable 2-core cable is connected to the interrupted wire ends using appropriate terminals. The other end of the cable is connected to the selected relay output of the MiniHPC (or to an auxiliary relay).
When using relay R1 or R2, these outputs can be connected directly to the interrupted heater wire of the outdoor unit, as shown in the following diagram:
When using relay R4 or R5, an auxiliary relay must be inserted between the relay output and the interrupted heater wire of the outdoor unit, as shown in the following diagram.
Switching controlled by MiniHPC independently of the outdoor unit
The connector labeled HEAT-B on the outdoor unit control board is disconnected and both orange wires are cut. A suitable 2-core cable is connected to the interrupted wires leading to the heating cable using appropriate terminals (e.g. WAGO). The other end of the cable is connected to the selected MiniHPC relay output.
When using relay R4 or R5, these outputs can be connected directly to the interrupted heater wire of the outdoor unit, as shown in the following diagram:
When using relay R1 or R2, a phase (L) must be supplied to one of the relay contacts from relay outputs R4 or R5. The other relay contact is connected to one of the wires leading from the outdoor unit heater. The second heater wire is connected to the neutral (N) conductor of R3, R4, or R5.
There is also another wiring option that allows the use of a single wire between the MiniHPC and the outdoor unit instead of two. In this case, one of the interrupted orange wires of the heater element is connected to the neutral (N) conductor directly at the outdoor unit terminal block, and the other orange wire is connected to the phase output of one of the MiniHPC relays.
Instead of a 4-core interconnection cable, a 5-core cable is routed to the prepared terminal block, where the fifth wire is used for switching the outdoor unit heater.
The author of this documentation assumes no responsibility for any damage to equipment, property, or personal injury that may arise from the use of the described procedures, wiring methods, or information.
Performing the described modification may violate the manufacturer's warranty conditions and result in the loss of warranty for the air-conditioning unit.
All modifications, wiring, and interventions in the electrical parts of the air-conditioning unit must be carried out exclusively by a qualified person holding the appropriate authorization to work on electrical equipment, in accordance with applicable laws and standards.
Use of this information is entirely at the user's own risk.