1 Selection and dimensioning of heat pumps

1.1 Heat pumps for the renovation market - dimensioning for an existing heating system

1.1.1 Heat requirement of the house to be heated

In the case of existing heating systems, the heat demand of the building to be heated must be redefined, since the heating output of the existing boiler is not a measure of the heat demand. Boilers are usually oversized and would therefore lead to oversized heat pumps. The exact calculation of the heat requirement is based on country-specific standards (e.g. EN 12831). A rough determination can be made from the previous energy consumption, the living space to be heated and the specific heat requirement. The heat demand can be roughly determined as follows:
Calculation for oil:

B._a * eta * H_u Q_N = -------------------- B._vh Calculation for gas:
B._a * eta Q_N = ---------------- B._vh Simplified calculation:
B._a Q_N = --------- 250 with:

• Q_N = Building heat demand

• B._a = Annual gas consumption (in kWh) or oil (in l)

• eta = efficiency of gas or oil heating

• B._vh = Annual full hours of use

• H_u = Calorific value of heating oil (in kWh / l)

The annual full hours of use depend on the type of building and the climatic region. The following table shows annual full-use hours according to VDI 2067 for various types of building.

Tab. 1.1: Annual full hours of use for different types of buildings

The specific heat requirement for single and two-family houses built between 1980 and 1994 is approx. 80 W / m². For houses that were built before 1980 and no additional thermal insulation measures have yet been taken, it is 100 W / m² up to 120 W / m². In the case of existing systems, the current state of the system must be taken into account.

1.1.2 Determination of the required flow temperature

In most oil and gas boiler systems, the boiler thermostat is set to a temperature of 70 ° C to 75 ° C. This high temperature is usually only required for hot water preparation. Downstream control systems of the heating system such as mixing valves and thermostatic valves prevent the building from overheating. If a heat pump is retrofitted, it is imperative that the flow and return temperatures actually required are determined in order to be able to determine the correct renovation measures.
There are two different ways of doing this:

• The heat demand calculation and heat demand of each room are known.
  In the heating output tables of the radiators, the output is specified as a function of the flow and return temperature (see Tab. 1.2). The room for which the highest temperature is required is then decisive for the maximum flow temperature in the heating system.

Table 1.2: Heat output of radiator sections (at room air temperature t_i= 20 ° C, according to DIN 4703)

• Experimental determination in the heating season (see Fig. 1.1)
  During the heating season, the flow and return temperatures are reduced when the thermostat valves are fully open until a room temperature of approx. 20–22 ° C is reached. Once the desired room temperature has been reached, the current flow and return temperatures as well as the outside temperature are noted and entered in the diagram below. With the aid of the diagram, the In fact required temperature level (low, medium, high temperature) can be read off.

Fig. 1.1: Diagram for the experimental determination of the actually required system temperatures

1.1.3 Which renovation measures have to be taken for an energy-saving heat pump operation?

Low temperature
Flow temperature for all rooms max. 55 ° C
If the required flow temperature is below 55 ° C, no additional measures are required. Any low-temperature heat pump can be used for flow temperatures of up to 55 ° C.

Mean temperature
Flow temperature in some rooms over 55 ° C
If the required flow temperature is above 55 ° C only in some rooms, measures should be taken to reduce the required flow temperature. To do this, only the radiators in the affected rooms are replaced in order to enable the use of a low-temperature heat pump.

Mean temperature
Flow temperatures in almost all rooms between 55 ° C and 65 ° C
If temperatures between 55 ° C and 65 ° C are required in almost all rooms, the radiators in almost all rooms have to be replaced or a medium-temperature heat pump can be used.

High temperature
Flow temperatures in almost all rooms between 65 ° C and 75 ° C If flow temperatures of 65 ° C to 75 ° C are required, the entire heating system must be converted or adapted. If this changeover is not possible or not wanted, a high-temperature heat pump must be used.

A reduction in heat demand through

• Exchange of windows

• Reduction of ventilation losses

• Insulation of storey ceilings, roof trusses or facades

brings savings in four different ways when renovating a heating system with a heat pump.

• By reducing the heat requirement, a smaller and therefore cheaper heat pump can be installed.

• A lower heat requirement leads to a reduction in the annual heating energy requirement that has to be supplied by the heat pump.

• The lower heat requirement can be covered with lower flow temperatures and thus improves the annual coefficient of performance.

• Better thermal insulation leads to an increase in the mean surface temperatures of the areas surrounding the room. As a result, the same level of comfort is achieved at lower room air temperatures.

Example:

A house with a heating requirement of 20 kW and an annual heating energy requirement of approx. 40,000 kWh is heated with a hot water heater with a flow temperature of 65 ° C (return 50 ° C). Subsequent thermal insulation measures reduce the heat requirement by 25% to 15 kW and the annual heating energy requirement to 30,000 kWh. As a result, the average flow temperature can be reduced by approx. 10 K, which lowers energy consumption by a further 20-25%. The total energy cost saving for a heat pump heating system is then approx. 44%.

1.1.4 Selection of the heat source (renovation)

In the renovation market for existing houses and landscaped gardens, it is rarely possible to build a geothermal collector, geothermal probe or well system. In most cases, the only possible source of heat remains the outside air. Air as a heat source is available everywhere and can always be used without a permit. The expected annual performance factors are lower than for water and ground systems, but the effort for developing the heat source system is lower. How the heat source system is dimensioned for brine and water / water heat pumps, please refer to the corresponding chapters.

1.2 Heat pumps for new systems to be built

1.2.1 Determination of the building heat requirement

The exact calculation of the maximum hourly heat requirement is based on country-specific standards. An approximate determination of the heat requirement is to be made using the living space to be heated A (m²) possible:

Heat requirement [kW] = heated area [m²] * spec. Heat demand [kW / m²]

Table 1.3: Approximate specific heat demand values for single-family houses

1.2.2 Design of the flow temperatures

When designing the heat distribution system of heat pump heating systems, it must be ensured that the required heat is transferred at the lowest possible flow temperatures, since every degree of temperature reduction in the flow temperature results in a saving in energy consumption of approx. 2.5%. Large heating surfaces such as underfloor heating are ideal. In general, the required flow temperature should not exceed 55 ° C in order to enable the use of low-temperature heat pumps. If higher flow temperatures are required, medium or high temperature heat pumps must be used (Section 1.1.3). In order to heat buildings with the lowest possible flow temperature (low-temperature heating system) and thus energy-efficiently, the consumer circuit must be designed for these system temperatures. The following heat sinks, for example, are suitable for operation with low flow temperatures:

• Underfloor heating

• Fan coil units

• Radiant ceiling panels

• Ventilation register (with large heat exchanger surface)

• Concrete core activation

A weather-dependent setting of the control is preferred in order to avoid unnecessarily high heating water temperatures during the partial load operation of the heat pump. By lowering the flow temperature when the outside temperature rises, an increase in energy efficiency is achieved. The fixed value control of the heat pump, which is also possible, should be set for brine / water heat pumps with a probe system, since the heat source has the same temperature level all year round.

1.2.3 Selection of the heat source

The decision as to whether the heat source air, brine (geothermal heat collector, geothermal probe) or water (well system) is used should be made depending on the following influencing variables.

• Investment costs In addition to the costs for the heat pump and the heat recovery system, the investment costs are decisively influenced by the development costs of the heat source.

• operating cost The expected annual performance factors of the heat pump heating system have a decisive influence on the operating costs. These are primarily influenced by the type of heat pump, the average heat source temperature and the required heating flow temperatures.

1.3 Additional power requirements

1.3.1 RU blocking times

Most energy supply companies (EVU) offer a special agreement with a cheaper electricity price for heat pumps. According to the Federal Tariff Ordinance, the power supply company must be able to switch off and block heat pumps in the event of load peaks in the supply network. The heat pump system for generating heat in the house is not available during the off-times. Therefore, energy must be added in the heat pump enable times, which means that the heat pump or the second heat generator must be dimensioned correspondingly larger.

Dimensioning The calculated heat demand values for heating and hot water preparation must be added. In the case of monovalent operation without a setpoint, an additional 2nd heat generator is not switched on during the blocking period, the sum of the heat demand values must be multiplied by the dimensioning factor f and the heat pump designed accordingly larger. In the case of mono-energetic or bivalent systems, the second heat generator can also provide the additional power required.

Calculation basis:

Table 1.4: Dimensioning factor f for taking blocking times into account

Due to the large number of network operators, the EVU block is used very differently. The bandwidth ranges from fixed daily locks to sporadic, load-dependent locks that are only used sporadically during load peaks in the network.

In general, in solidly built houses, especially with underfloor heating, the existing heat storage capacity is sufficient to bridge the maximum blocking period of two hours with only a slight loss of comfort, so that the second heat generator (e.g. boiler) does not need to be switched on during the blocking period. However, the increase in output of the heat pump or the second heat generator is necessary because of the required reheating of the storage masses.

1.3.2 DHW heating

The demand for hot water in buildings is heavily dependent on usage behavior.

With normal comfort requirements, a rough average daily hot water requirement of 1.45 kWh per person can be assumed. At a storage temperature of 60 ° C, this corresponds to an amount of water of 25 l per person. In this case, an additional heat pump output of 0.2 kW per person for the hot water must be taken into account.

Simplified process

In the one- and two-family house area with standard sanitary equipment, the required storage tank size and the required heating power can be determined with the help of a simplified procedure.

This value is doubled for storage capacity up to approx. 10 people - thus the required minimum storage volume is obtained. This minimum volume is converted to the actual storage temperature.

If the hot water preparation takes place at the design point of the heat pump by means of a flange heater, it is not necessary to add the additional energy requirement for hot water preparation to the heating requirement.

Circulation lines
Circulation lines increase the heat requirement for hot water heating on the system side. The additional requirement depends on the length of the circulation line and the quality of the line insulation and must be taken into account accordingly. If circulation cannot be dispensed with due to the long pipeline routes, a circulation pump should be used that is activated by a flow sensor if required. The heat requirement for the circulation line can be considerable.

The area-related heat loss of the drinking water distribution depends on the usable area and the type and location of the circulation used. With a usable area of 100 to 150 m² and a distribution within the thermal envelope results in area-related heat losses according to EnEV of:

n (with circulation) = 9.8 [kWh / m²a]

n (without circulation) = 4.2 [kWh / m²a]

1.3.3 Swimming pool water heating

outdoor pool The heat requirement for pool water heating in the outdoor pool depends heavily on usage habits. In terms of magnitude, it can correspond to the heat demand of a residential building and must be calculated separately in such cases. However, if there is only occasional heating in summer (heating-free time), the heat demand may not need to be taken into account. The approximate determination of the heat requirement depends on the wind position of the pool, the pool temperature, the climatic conditions, the period of use and whether the pool surface is covered.

_{1 Reduced values for pools with a cover only apply to private swimming pools when used for up to 2 hours per day}

Tab. 1.5: Reference values for the heat demand of outdoor pools when used from May to September

For the initial heating of the pool to a temperature of over 20 ° C, a heat quantity of approx. 12 kWh / m is required³ Pool content required. Depending on the size of the pool and the installed heating capacity, heating times of one to three days are required.

Indoor swimming pool

• Space heating
  The room is generally heated via radiator or underfloor heating and / or a heating register in the dehumidification / ventilation system. In both cases, a heat demand calculation is necessary - depending on the technical solution.

• Swimming pool water heating
  The heat requirement depends on the pool water temperature, the temperature difference between pool water and room temperature and the use of the swimming pool.

Tab. 1.6: Reference values for the heat requirement of indoor swimming pools

In the case of private swimming pools with a pool cover and use of a maximum of 2 hours per day, these services can be reduced by up to 50%.

1.3.4 Determination of the heat pump output

1.3.4.1 Heat pump with one output level (Fix-Speed)

Fix-Speed heat pumps are controlled by switching the compressor on and off. The cooling circuit including the heat exchanger surfaces is optimized for the full performance of the compressor. Operating advantages are particularly evident in systems that have a high heat requirement at approx. 2 ° C, e.g. in bivalent systems or systems with high storage masses, e.g. open underfloor heating systems, since the compressor is operated with maximum efficiency even when there is a high heat requirement.

Overdimensioning in connection with a lack of storage mass leads to short runtimes, the machine clocks. This behavior occurs more intensely in the transition period.

_{Heating capacity in kW}

_{Outside temperature in ° C}

_{- heating power characteristic}

_{- Fixed-speed characteristic}

Fig. 1.2: Heating output curve, heat pump with one output level (fixed speed)

1.3.4.2 Output-controlled heat pumps with two output levels (stepped control)

Step-controlled heat pumps are controlled by switching two compressors on and off. The cooling circuit including the heat exchanger surfaces is optimized for operation with one compressor, as one compressor can often cover over 80% of the annual heating work. When the outside temperature is low, additional power is available by switching on the second compressor. At higher outside temperatures, only the capacity of one compressor is available.

Oversizing (e.g. monovalent design) is less critical, as this simply increases the proportion of more efficient single-compressor operation. Ideally, the heat pump covers the building's heat demand with an outside temperature of approx. 2 ° C with the output of a compressor. In bivalent systems, the bivalence point should be below 0 ° C.

_{Heating capacity in kW}

_{Outside temperature in ° C}

_{- heating power characteristic}

_{- Performance level 1 (2-level)}

_{- Performance level 2 (2-level)}

Fig.1.3: Heating output curves for heat pumps with two output levels (stepped control)

1.3.4.3 Output-controlled heat pumps with inverters

In the case of steplessly controlled inverter heat pumps, the output of the compressor is controlled via the frequency. The cooling circuit including the heat exchanger surfaces is optimized for partial load operation with the aim of achieving a high annual coefficient of performance. Ideally, the system is dimensioned so that the control range of the inverter is sufficient to enable continuous operation of the heat pump between approx. -7 ° C and + 7 ° C outside temperature. The heat pump only needs to be supported by a second heat generator when the outside temperature is lower. At higher outside temperatures, outside the control range, the control takes place by switching off the compressor (analogous to Fix-Speed).

Oversizing leads to the fact that the inverter is operated more and more outside its control range, which in turn leads to increased clocking and thus to a control behavior similar to a fix-speed heat pump, control by switching on and off.

_{Heating capacity in kW}

_{Outside temperature in ° C}

_{- heating power characteristic}

_{- performance curve minimal (variable)}

_{- Maximum performance curve (variable)}

Fig. 1.4: Heating output curves for output-controlled heat pumps with inverters

1.3.4.4 Air / water heat pump (monoenergetic operation)

Air / water heat pumps are mainly operated as mono-energetic systems. Depending on the climate zone, the heat pump should completely cover the heat demand from –2 ° C to approx. -5 ° C outside temperature (equilibrium point). At low temperatures and high heat requirements, an electrically operated heat generator is switched on as required. The dimensioning of the heat pump output influences the level of investment and the annual heating costs, particularly in the case of monoenergetic systems. The higher the output of the heat pump, the higher the investment in the heat pump and the lower the annual heating costs. Experience has shown that the aim is to achieve a heat pump output that intersects the heating curve at a limit temperature (or equilibrium point) of approx. -5 ° C. With this design, according to VDI 4650 DIN 4701 T10, a bivalent-parallel operated system results in a share of the 2nd heat generator (e.g. heating element) of 2%. The following Fig. 1.5 shows, for example, the annual characteristic curve for the outside temperature in Essen. According to this, there are fewer than 10 days a year with an outside temperature of below -5 ° C.

• A monovalent design of air / water heat pumps is permitted

• The system should be hydraulically optimized in such a way that there is no permanent cyclical operation (buffer tank size, hydraulic balancing, heating curve setting, ...)

• Overdimensioning for security reasons or due to EVU blocks should be avoided

In the case of a monovalent heat pump, it must be ensured that sufficient storage masses prevent the heat pump from cycling. This can be done by increasing the buffer volume or by using the storage mass of the underfloor heating. Hydraulic balancing and the correct setting of the heating curve are essential. The ideal combination with the intelligent room temperature control, which adapts the system temperature to the actual heat demand and thus contributes to longer running times of the heat pump, among other things.

Fig. 1.5 .: Annual characteristic curve: Number of days on which the outside temperature is below the specified value

Example for Tab. 1.7: With a bivalence point of 5 ° C, a heat pump share of approx. 98% results in bivalent-parallel operation.

Tab.1.7: Coverage share of the heat pump in a mono-energetic or bivalent-operated system depending on the bivalence point and the operating mode (source: Table 5.3-4 DIN 4701 T10)

1.3.4.5 Design example for an air / water heat pump

The heat pump is dimensioned using the outside temperature-dependent building heat demand (simplified as a straight line) in the heat output diagram and the heat output curves of the heat pumps. The outside temperature-dependent building heat demand is entered from the selected room temperature (corresponding outside temperature point 1) on the abscissa (x-axis) to the calculated heat output (point 2) at standard outside temperature according to country-specific standards.

Fig. 1.6: Heating output curves of two air / water heat pumps with different heating outputs for flow temperatures of 35 ° C and outside temperature-dependent building heating requirements

The example from Fig. 1.6 with a total heating requirement of the house of 11.0 kW at a standard outside temperature of 16 ° C and a selected room temperature of +20 ° C illustrates the procedure. The diagram shows the heating output curves of two heat pumps for a heating water flow temperature of 35 ° C. The points of intersection (limit temperature or bivalence points) from the straight line of the outside temperature-dependent building heat demand and the heating output curves of the heat pumps are approx. -5 ° C for HP 1 and approx. -9 ° C for HP 2. For the selected example is to use the WP 1. So that year-round heating can take place, the difference between the outside temperature-dependent building heat requirement and the heating output of the heat pump at the corresponding air inlet temperature must be compensated for by an additional electrical heater.

Design of the electrical auxiliary heating:

Example:

For the selected example, HP 1 is to be dimensioned with an electrical output of the heating elements of 6.0 kW.

1.3.4.6 Design of brine / water and water / water heat pumps (monovalent operation)

Fig. 1.7 shows the heating output curves of brine / water heat pumps. The heat pump whose heating output is above the intersection of the required total heat demand and the available heat source temperature is to be selected.

Fig. 1.7: Heating capacity curves of brine // water heat pumps with different heating capacities for flow temperatures of 35 ° C.

With a total heat requirement of 13.8 kW and a minimum brine temperature of 0 ° C, the performance curve of WP 5 must be selected with a maximum required flow temperature of 35 ° C. Under the above-mentioned boundary conditions, this delivers a heat output of 14.5 kW.

1.3.4.7 Design of brine / water and water / water heat pumps (monoenergetic operation)

Monoenergetic brine / water or water / water heat pump systems are equipped with a second, also electrically operated heat generator, e.g. a buffer storage tank with an electric immersion heater. The planning of mono-energetic brine / water or water / water heat pump systems should only be carried out in exceptional cases, if a very high performance surcharge is necessary due to blocking times or a heat pump with a significantly higher performance compared to the total heat requirement would have to be selected due to the range. In addition, mono-energetic operation is ideal for the first heating season when the building dries out in autumn or winter.

1.3.4.8 Design of air / water heat pumps (bivalent operation - hybrid systems)

At a bivalent-parallel In operation (old building and / or hybrid systems), a second heat generator (fossil: oil or gas boiler; regenerative: pellet stove, solar thermal) supports the heat pump from the bivalence point. Below the bivalence point can both heat generators are operated in parallel.

In existing buildings with classic (cast) radiators as a heat distribution system, heating flow temperatures of 50 ° C and more are sometimes possible. If an optimization of the heat distribution system is not possible, a bivalent-alternative Operation of heat pumps and boilers, as air / water heat pumps in particular have significantly better coefficients of performance at higher outside temperatures. At low outside temperatures (see equilibrium point) the 2nd heat generator takes over the heating of the building.

Fig. 1.8: Coverage share of a heat pump in different operating modes

The diagram shows the share of coverage of a heat pump for the operating modes bivalent-parallel and bivalent-alternative depending on the building's heat demand for an example building.

1.3.4.9 Design of brine / water and water / water heat pumps (bivalent operation)

In the case of bivalent operation of water / water and brine / water heat pumps, the same relationships apply in principle as for air / water heat pumps. Depending on the system of the heat source system, the other dimensioning factors of the heat source (extraction capacity of the heat pump, hours of full use) must be taken into account and adjusted.

1.3.4.10 Building drying / screed drying

When building a house, depending on the construction method, a certain amount of water is used for mortar, plaster, plaster and wallpaper, which only slowly evaporates from the structure. In addition, rain can increase the moisture in the building. Due to the high level of humidity in the entire building, the heating requirement of the house is increased in the first two heating seasons.

The building should be dried out with special, on-site devices. If the heating output of the heat pump is limited and the building dries out in autumn or winter, an additional electric immersion heater or a replacement heater must be installed in accordance with VDI 4645. This must be taken into account, especially with brine / water heat pumps, in order to compensate for the increased heat demand and to relieve the heat source.

1.3.5 General information on the hydraulic connection of heat pumps

Connection on the heating side
The connection on the heating side must be carried out by qualified personnel using personal protective equipment. The respective connection sizes and thread types can be found in the device information for the heat pump. When connecting to the heat pump, the transitions must be held in place with a key. Empty pipes must be sealed after installation on the heat pump.

Before the heat pump is connected on the heating water side, the heating system must be flushed in order to remove any impurities, residues of sealing material or the like. An accumulation of residues in the condenser can lead to total failure of the heat pump.
After the installation on the heating side has been completed, the heating system must be filled, vented and pumped off.
Please note the following when filling the system:

• the fill and top-up water must be of drinking water quality (colorless, clear, without deposits)

  and be pre-filtered (pore size max. 5 μm). For more information, see Chapter 8.9 - Stone Formations ...

• Furthermore, the installation and operating instructions for components used on site (e.g. pumps, valves, storage tanks ...) must be observed.

1.3.6 General information on the electrical connection of heat pumps

1.3.6.1 Miniature circuit breaker and residual current circuit breaker (RCD)

The size and type of the required circuit breaker can be found in the documents supplied (electrical documentation, device information, instructions) or on the nameplate of the respective heat pump. The use of a circuit breaker with a different trigger characteristic or a higher trigger value is not permitted.

Depending on the conditions of use and the installation environment, the use of an upstream RCD is necessary. The information and boundary conditions for the use of a residual current circuit breaker include: can be found in the generally applicable VDE regulations. If a residual current circuit breaker is installed, it must at least correspond to the RCD type specified in the device information or the electrical documentation for the heat pump.

1.3.6.2 Cable laying

The environmental conditions (e.g. indoor or outdoor installation, wet room, ...) are decisive for the correct execution of the electrical installation. In accordance with these requirements, a suitable cable type must be used and the cables must be routed in accordance with regulations.

1.3.6.3 Design, project planning and installation of surge protection / lightning protection

In times of digitalization, living comfort and networked building technology, the lightning and surge protection of residential buildings is also of immense importance. In all new residential buildings as well as in the event of changes and extensions to the electrical installation, attention must be paid to the use of overvoltage protection measures. The design, planning and installation of the surge protection / lightning protection is the responsibility of the planner or installer.
The following parts of the DIN VDE 0100 standard regulate:

-443: WHEN overvoltage protection measures are to be provided in systems and buildings.

-534: HOW the arrester is to be selected, installed and installed in the electrical system.

According to the technical interpretation of these standards, it is possible to differentiate between mandatory and recommended measures for overvoltage protection in residential buildings.

Measures for the power supply lines introduced into the residential building are currently mandatory. For Internet, telephone and broadband cable lines, DIN VDE 0100-443 cannot require surge protection measures, but only recommend them. However, a safe and effective surge protection concept can only be achieved if surge arresters are used for all electrical lines that are introduced, and thus also for communication lines.

A surge arrester is therefore required at the entrance to the building for each of these lines (power supply, telephone line and broadband cable). In the case of high-quality, sensitive end devices or if the system part needs special protection (e.g. heat pump), it is necessary to check whether further overvoltage protection measures are required. Because despite a surge arrester already installed at the building entrance, coupling can cause damage to end devices or system parts that are more than 10 meters away from the last surge protection device due to their cable length. The installation of additional overvoltage protection devices ensures that the voltage is limited in accordance with the insulation strength of the electrical or electronic devices and that damage to sensitive devices is avoided.

The aspect of the cable length can also be found in DIN VDE 0100-534. The standard speaks of the so-called "effective protection area of overvoltage protection devices". As in other standards, this was specified as 10 meters. This means that the effectiveness of the overvoltage protection device in the feed may no longer be sufficient after 10 meters.

It is therefore advisable to check whether further protective measures are required. These must be installed as close as possible to the device to be protected (e.g. heat pump) or in the last upstream sub-distribution. Additional overvoltage protection is therefore particularly recommended for components of a heat pump if

• the cable length to sensitive end devices or system parts is more than 10 meters,

• Cables extending beyond the building to external system components (e.g. external unit heat pump) are available,

• Loops are set up in the installation (e.g. when laying high / low current, WLAN routers),

• there are other or tall buildings (e.g. churches or skyscrapers) nearby.

Coordinate the measures for downstream surge arresters with the owner and adapt them to the individual protection needs of the building or the owner. These requirements / recommendations apply exclusively to buildings without an external lightning protection system. A possible lightning and surge protection concept to protect all components of a heat pump system is shown in Figure 1.6.

Fig .: 1.9 Lightning and surge protection concept using the M / M Flex system as an example

Legend to Fig. 1.9

Additional information, data sheets and planning documents on the subject of lightning protection can be found e.g. under www.dehn.de.

1.3.6.4 Electrical connection of heat pumps (general)

The power connection of the heat pump is made using a standard 5-core cable. The cable must be provided by the customer and the line cross-section selected according to the power consumption of the heat pump (see device information appendix) and the relevant VDE (EN) and VNB regulations.
In the power supply for the heat pump, an all-pole disconnection with at least 3 mm contact gap (e.g. EVU blocking contactor, power contactor), as well as a 3-pole automatic circuit breaker with common tripping of all outer conductors, must be provided (tripping current according to the device information of the respective heat pump).
The relevant components in the heat pump contain internal overload protection.

When connecting, the clockwise rotating field of the load feed must be ensured.

Phase sequence: L1, L2, L3.

• The control voltage is supplied via the heat pump manager. To do this, a 3-pole cable is to be laid based on the electrical documentation. Further information on the wiring of the heat pump manager can be found in the operating instructions.

• A shielded communication line (J-Y (ST) Y ..LG) (provided by the customer - not included in the scope of delivery of the heat pump) connects the heat pump manager with the WPIO controller built into the heat pump. More detailed instructions can be found in the instructions for use of the heat pump manager and the electrical documentation.

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