Values are indicative. Always calculate to IEC 60364-5-52 and local standards.<\/p>\n<\/div>\n
Cable routing considerations:<\/strong><\/p>\n\n- Maintain separation between power and control cables (minimum 100 mm, or use shielded control cable)<\/li>\n
- Use conduit or cable duct in exposed areas<\/li>\n
- Avoid routing near heat sources<\/li>\n
- Follow manufacturer cable entry points and strain relief requirements<\/li>\n<\/ul>\n
Protective Devices<\/h3>\n
Definition:<\/strong> Protective devices are electrical components that interrupt the circuit under fault conditions. They protect the heat pump, the wiring, and the building from overcurrent, short circuits, and earth faults.<\/p>\nPurpose:<\/strong> Limits damage and prevents fire or electric shock in fault conditions.<\/p>\nBenefits:<\/strong><\/p>\n\n- Complies with IEC 60364, VDE 0100, \u00d6VE\/\u00d6NORM E 8001, and SEV 1000<\/li>\n
- Protects the compressor from sustained overcurrent<\/li>\n
- Provides safe isolation point for service and maintenance<\/li>\n<\/ul>\n
Required protective devices for heat pump circuits:<\/strong><\/p>\n\n- Miniature Circuit Breaker (MCB):<\/strong> Protects against overload and short circuit. Characteristic curve B or C depending on compressor type. Sized to rated current with appropriate trip margin.<\/li>\n
- Residual Current Circuit Breaker (RCCB \/ FI-Schalter):<\/strong> Detects earth leakage current. Type A minimum for heat pumps with electronic speed control (inverter). Type B required where DC leakage is possible (mandatory in many DACH installations for inverter-driven compressors per IEC 62423).<\/li>\n
- Surge Protection Device (SPD):<\/strong> Protects control electronics from transient overvoltage. Especially important for outdoor-mounted monobloc units.<\/li>\n
- Isolator \/ Main Switch:<\/strong> Provides lockable isolation for service. Must be accessible without entering a restricted space.<\/li>\n<\/ul>\n
\nRegulatory note:<\/strong> In Austria, \u00d6VE\/\u00d6NORM E 8001 Part 1 and Part 6 apply. In Germany, DIN VDE 0100-701 and the Niederspannungsanschlussverordnung (NAV) govern the grid connection process. In Switzerland, the Niederspannungsinstallationsnorm (NIN 2020) is the governing standard.<\/p>\n<\/blockquote>\nEarthing and Equipotential Bonding<\/h3>\n
Definition:<\/strong> Earthing connects the metal enclosure of the heat pump to the protective earth (PE) conductor of the building’s electrical system. Equipotential bonding connects all metallic parts of the heating system \u2014 pipework, heat exchanger housing, buffer tank \u2014 to the same earth reference.<\/p>\nPurpose:<\/strong> Prevents dangerous touch voltages on accessible metal parts if an internal fault occurs.<\/p>\nBenefits:<\/strong><\/p>\n\n- Ensures RCD trips within the required time under fault conditions<\/li>\n
- Prevents electrochemical corrosion caused by stray currents<\/li>\n
- Required for all Class I equipment under IEC 61140<\/li>\n<\/ul>\n
Practical application:<\/strong> The PE conductor must be continuous from the distribution board to the heat pump terminals. Outdoor units must have the earth connection made before energisation. For split systems with refrigerant lines, the indoor and outdoor units must both be individually earthed.<\/p>\nControl Wiring and Low-Voltage Circuits<\/h3>\n
Definition:<\/strong> Control wiring connects the heat pump controller to external components including room thermostats, weather compensation sensors, domestic hot water sensors, buffer tanks, zone valves, and energy management systems.<\/p>\nPurpose:<\/strong> Enables the heat pump to receive demand signals and adjust output accordingly.<\/p>\nBenefits:<\/strong><\/p>\n\n- Allows modulating operation based on actual building demand<\/li>\n
- Enables integration with smart home systems and building energy management<\/li>\n
- Supports time-of-use tariff optimisation<\/li>\n<\/ul>\n
Common control connections in iDM heat pump installations:<\/strong><\/p>\n<\/div>\n\n
\n\n\n| Signal<\/th>\n | Description<\/th>\n | Cable type<\/th>\n<\/tr>\n<\/thead>\n |
\n\n| Outdoor temperature sensor<\/td>\n | Weather compensation input<\/td>\n | 2-wire, shielded, 0.75 mm\u00b2<\/td>\n<\/tr>\n |
\n| Domestic hot water demand<\/td>\n | DHW priority signal<\/td>\n | 2-wire, 24 V or potential-free contact<\/td>\n<\/tr>\n |
\n| Room thermostat \/ room controller<\/td>\n | Heating\/cooling demand<\/td>\n | 2-wire or bus (iDM Navigator system)<\/td>\n<\/tr>\n |
\n| SG Ready interface<\/td>\n | Smart grid load management<\/td>\n | 2-wire, potential-free contact<\/td>\n<\/tr>\n |
\n| EVU block \/ utility contact<\/td>\n | Utility company load control<\/td>\n | 2-wire, potential-free contact<\/td>\n<\/tr>\n |
\n| BMS \/ Modbus \/ CAN<\/td>\n | Building management integration<\/td>\n | Shielded twisted pair or specific bus cable<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\nSG Ready Interface and Smart Grid Integration<\/h3>\nDefinition:<\/strong> SG Ready is a German\/Austrian heat pump industry standard (defined by BWP \u2013 Bundesverband W\u00e4rmepumpe) that defines four operating modes controlled via two external contacts. It allows grid operators and energy management systems to signal the heat pump to shift load.<\/p>\nPurpose:<\/strong> Enables demand-side management. The heat pump can increase load when renewable electricity is abundant (e.g., midday PV surplus) and reduce load when the grid is stressed.<\/p>\nSG Ready operating modes:<\/strong><\/p>\n<\/div>\n\n \n\n\n| Mode<\/th>\n | Contact 1<\/th>\n | Contact 2<\/th>\n | Heat Pump Behaviour<\/th>\n<\/tr>\n<\/thead>\n | \n\n| 1 \u2013 Blocked<\/td>\n | Closed<\/td>\n | Open<\/td>\n | Compressor blocked (EVU lock)<\/td>\n<\/tr>\n | \n| 2 \u2013 Normal<\/td>\n | Open<\/td>\n | Open<\/td>\n | Standard operation<\/td>\n<\/tr>\n | \n| 3 \u2013 Increased<\/td>\n | Open<\/td>\n | Closed<\/td>\n | Elevated set-point, increased load<\/td>\n<\/tr>\n | \n| 4 \u2013 Maximum<\/td>\n | Closed<\/td>\n | Closed<\/td>\n | Maximum operation, full load<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\nBenefits:<\/strong><\/p>\n\n- Reduces electricity costs by running during low-tariff periods<\/li>\n
- Integrates with photovoltaic systems for self-consumption optimisation<\/li>\n
- Satisfies requirements for heat pump subsidies in DACH region (e.g., Austrian Klimabonus, German BEG programme conditions)<\/li>\n<\/ul>\n
<\/span>Types of Electrical Connection Configurations<\/span><\/h2>\nSingle-Phase Connection (1~\/N\/PE, 230 V)<\/h3>\nUsed for smaller heat pumps, typically up to 3.5 kW electrical input. Common in renovations where three-phase power is not available. Limitations include lower starting torque and higher current draw per phase.<\/p>\n Three-Phase Connection (3~\/N\/PE, 400 V)<\/h3>\nStandard for residential and commercial heat pumps above 3.5 kW. Provides balanced load distribution. Required by most grid operators for heat pumps with compressors above 2.2 kW shaft power.<\/p>\n Separate Meter \/ Heat Pump Tariff Connection<\/h3>\nIn Austria and Germany, a second electricity meter can be installed for the heat pump circuit. This enables access to preferential heat pump electricity tariffs (W\u00e4rmepumpenstrom \/ W\u00e4rmepumpen-Tarif) with lower per-kWh costs. The utility retains the right to interrupt supply for up to two hours per interruption, three times per day \u2014 managed via the EVU block contact or SG Ready mode 1.<\/p>\n Direct Connection vs. Sub-Distribution<\/h3>\nFor large residential or commercial installations, the heat pump may be connected via a dedicated sub-distribution board (Unterverteilung). This separates the heat pump circuit from household circuits, simplifies service isolation, and provides space for all required protection devices.<\/p>\n <\/span>Installation Process: Step-by-Step Electrical Connection<\/span><\/h2>\nA correct electrical connection follows a defined sequence. Deviations increase risk and invalidate warranty claims.<\/p>\n Step 1 \u2014 Grid operator notification<\/strong> Submit a connection application to the local grid operator (Netzbetreiber\/Netzbetreiber) before installation. Required in Austria under ElWOG, in Germany under EnWG and NAV, in Switzerland under StromVG.<\/p>\nStep 2 \u2014 Load assessment<\/strong> Calculate the heat pump’s rated current from the technical datasheet. Verify available grid capacity at the connection point. Confirm single-phase or three-phase supply.<\/p>\nStep 3 \u2014 Cable selection<\/strong> Select cable type, cross-section, and length according to IEC 60364-5-52 and local standards. Account for installation method (conduit, trunking, buried) and ambient temperature correction factors.<\/p>\nStep 4 \u2014 Distribution board preparation<\/strong> Install MCB, RCCB (Type A or B as required), and SPD in the distribution board. Label the circuit. Provide lockable isolation point.<\/p>\nStep 5 \u2014 Cable routing<\/strong> Route the supply cable from the distribution board to the heat pump. Maintain separation from control cables. Secure cable at required intervals. Install cable gland at heat pump entry point.<\/p>\nStep 6 \u2014 Terminal connection<\/strong> Connect supply conductors (L1, L2, L3, N, PE) to the heat pump terminals in the correct sequence. Verify terminal torque values from the installation manual (typical: 1.5\u20134 Nm for 4\u201316 mm\u00b2 conductors). Do not over-torque.<\/p>\nStep 7 \u2014 Control wiring<\/strong> Connect sensor cables, bus cables, and external control contacts. Follow the wiring diagram in the manufacturer’s installation manual. Use shielded cable where specified.<\/p>\nStep 8 \u2014 Earth and equipotential bonding<\/strong> Verify PE continuity from distribution board to heat pump terminals. Connect pipework bonding conductor where required by local standards.<\/p>\nStep 9 \u2014 Insulation resistance test<\/strong> Before energisation, measure insulation resistance between all live conductors and earth. Minimum 1 M\u03a9 per IEC 60364-6. Disconnect the heat pump controller before testing to protect electronics.<\/p>\nStep 10 \u2014 Functional test<\/strong> Energise the circuit. Verify supply voltage at heat pump terminals (tolerance typically \u00b110% of rated voltage). Test RCCB by pressing the test button. Confirm all control signals are received by the controller. Start the heat pump in service mode and observe startup sequence.<\/p>\nStep 11 \u2014 Documentation<\/strong> Complete the electrical installation certificate \/ Pr\u00fcfprotokoll. Record measured values (insulation resistance, earth loop impedance, RCD trip time). File documentation for warranty, subsidy applications, and inspection.<\/p>\n<\/span>Use Cases<\/span><\/h2>\nNew-Build Residential Installation<\/h3>\nA new build with an iDM TERRA air-to-water heat pump requires a dedicated three-phase circuit from the main distribution board, SG Ready integration with the building’s photovoltaic inverter, and a separate heat pump tariff meter. The electrical connection is planned alongside the building’s full electrical design.<\/p>\n Renovation \/ Boiler Replacement<\/h3>\nReplacing a gas boiler with a heat pump in an older building often requires a main fuse upgrade (Hauptsicherungserh\u00f6hung) and installation of a Type B RCCB if the existing board only carries Type AC devices. The electrician must assess the existing wiring before installing new circuits.<\/p>\n Commercial \/ Multi-Family Residential<\/h3>\nLarge heat pumps (above 30 kW) require three-phase connection, dedicated metering, power factor correction consideration, and often a formal grid connection study. Modbus or BACnet integration connects the heat pump to the building management system.<\/p>\n Heat Pump with PV System<\/h3>\nWhen a heat pump operates alongside a photovoltaic system, the SG Ready interface or Modbus connection enables the energy manager to direct surplus PV power into the heat pump, increasing self-consumption. This is a primary use case for iDM Navigator energy management functionality.<\/p>\n <\/span>Benefits of a Correctly Executed Electrical Connection<\/span><\/h2>\n<\/div>\n\n \n\n\n| Benefit<\/th>\n | Description<\/th>\n<\/tr>\n<\/thead>\n | \n\n| Operational reliability<\/td>\n | Correct cable sizing and protection prevents nuisance tripping and compressor damage<\/td>\n<\/tr>\n | \n| Energy cost reduction<\/td>\n | SG Ready and tariff meter access reduce per-kWh costs by 20\u201340% in favourable tariff structures<\/td>\n<\/tr>\n | \n| Regulatory compliance<\/td>\n | Meets \u00d6VE, VDE, SEV, and IEC requirements for safe electrical installation<\/td>\n<\/tr>\n | \n| Subsidy eligibility<\/td>\n | Austrian Klimabonus, German BEG, Swiss cantonal subsidies require compliant, certified installation<\/td>\n<\/tr>\n | \n| Warranty protection<\/td>\n | Manufacturer warranty is conditional on installation to published standards<\/td>\n<\/tr>\n | \n| Longevity<\/td>\n | Correct earthing and surge protection extends the life of control electronics<\/td>\n<\/tr>\n | \n| Smart grid readiness<\/td>\n | SG Ready and Modbus connections prepare the system for future energy management expansion<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/span>Selection Criteria for Electrical Components<\/span><\/h2>\nWhen specifying components for the electrical connection, consider:<\/p>\n For protective devices:<\/strong><\/p>\n\n- RCCB type must match compressor technology: Type A for standard inverter drives, Type B where high-frequency DC leakage is possible<\/li>\n
- MCB trip characteristic: Curve B for normal resistive loads, Curve C or D where high inrush current occurs<\/li>\n
- Short-circuit rating (kA) must match or exceed the prospective short-circuit current at the installation point<\/li>\n<\/ul>\n
For cables:<\/strong><\/p>\n\n- Use cables rated for continuous outdoor use if routing outside or through unheated spaces<\/li>\n
- Halogen-free (LSOH\/HFFR) cables recommended for indoor sections<\/li>\n
- Shielded control cable mandatory for bus systems and sensor circuits longer than 10 m<\/li>\n<\/ul>\n
For the SG Ready \/ control interface:<\/strong><\/p>\n\n- Verify the heat pump controller supports SG Ready as standard or as an option<\/li>\n
- Confirm potential-free contact rating matches the energy management system’s output specifications<\/li>\n
- For Modbus integration, confirm RS485 interface availability on the heat pump controller<\/li>\n<\/ul>\n
<\/span>Comparison: Single-Phase vs. Three-Phase Electrical Connection<\/span><\/h2>\n<\/div>\n | | |