Maintenance of heat pumps

While the prices for fossil fuels have been setting unimagined records for weeks and months, an alternative to heating is coming into focus: the heat pump. These climate-friendly heating systems can also cool and heat tap water if required. Regardless of whether a building is to be heated with an air-to-air or air-to-water heat pump, it can only work at maximum efficiency if it is serviced regularly. In this advice, you will learn which steps you need to take for professional maintenance and repair.

Correct setting is half the battle: important measurement parameters for a heat pump

In order to be able to adequately determine the efficiency of a heat pump, various nominal values and parameters are used for comparison. If a heating system meets the most important requirements, it is not only particularly efficient, but also significantly more sustainable than firing systems that heat with oil or gas, for example.

Important metrics

In order to be able to compare heat pumps appropriately with each other, you can consult three key figures in particular: the GWP value, the COP and the SPF.

GWP stands for Global Warming Potential. This value indicates how sustainable the coolant used in the heater is. Carbon dioxide has the lowest value at 1. This is also used as a benchmark for the coolant. The higher the GWP value, the higher the resulting CO₂
The COP or Coefficient of Performance describes the relationship between the heat output delivered by the heat pump and the electrical energy consumed. It should be noted that the COP does not apply to the entire heating system, but only to the heat pump as an individual component.
The annual performance factor (SPF) records the heat energy that is given off by the entire heating system within a year and puts this in relation to the amount of electricity consumed in this period. With an AC of 3, 3kWh of heat are generated by 1kWh of electricity. The higher the annual performance factor, the more efficiently the system works.

Read measurement parameters correctly

The most important parameters for determining the current efficiency of a heat pump are subcooling and superheating.

Subcooling helps determine the efficiency of the refrigerant cycle. On the one hand, it ensures that pressure drops in the liquid line can be overcome without pre-evaporation. On the other hand, subcooling increases the amount of heat that the evaporator can absorb. It should therefore always be determined before the expansion device.
In contrast, superheat can be determined at four different locations: after the evaporator (evaporator superheat), in the suction line, before the evaporator (suction superheat) and in the compressor (additional superheat).

You can use the testo Smart Probes refrigeration set with built-in Bluetooth® function to test whether a heat pump system works as efficiently as specified. It is able to automatically calculate the corresponding values for superheat and subcooling. The hose-free application also guarantees you particularly low heat loss.

In addition, over 90 different refrigerants are stored in the testo Smart Probes app, so that you can check the efficiency of all common heat pumps. With a Bluetooth® range of 100m, you are also well prepared for particularly flexible applications. You can send the corresponding measurement data logs as a PDF or Excel file in no time at all via the app as an e-mail.

Modern heat pump in the garden — Regular maintenance ensures maximum efficiency.

Prevent breakdowns – thanks to suitable maintenance technology

Basically, there is a maintenance obligation for heat pumps depending on the refrigerant. This should ensure that no gradual malfunctions or even the loss of refrigerant from the pump are overlooked. In order to ensure that a specialist can also correctly evaluate and regulate the measured values supplied, the corresponding digital refrigeration measurement technology is indispensable. With the testo 557s smart vacuum set, you can carry out completely wireless measurements on heat pumps. With the handy and robust housing, you get reliable measurement results that you can document directly in the testo Smart App via Bluetooth® connection. In this way, you can detect even the smallest loss of refrigerant at an early stage and can prevent a failure of the heat pump and thus the entire heating system in good time.

Avoid unwanted residues – evacuation of heat pumps

One of the most important steps in the (re)commissioning of a heat pump is definitely the professional evacuation of the system. Residual gases or excess moisture, but also oils, are removed from the heat pump. The digital vacuum gauge testo 552 helps you to reliably and conveniently monitor the absolute pressure of the system wirelessly during the evacuation. With a measuring rate of 0.5s, the device not only provides you with particularly precise data on the dehumidification status of the system, you can also easily comply with the manufacturer’s specifications for evacuation thanks to an optical alarm if limit values are exceeded.

With a measurement accuracy of ±(10 microns + 10% of mv.), even the smallest absolute pressures can be mapped without any problems. Simple documentation via the app is also ensured via the existing Bluetooth® interface.

Finding leaks: How to protect a heat pump from permanent damage

Leaks in the heating system are not only extremely unpleasant, they can also have serious long-term consequences for the system and the environment. With the testo 316-3 leak detector, you can detect all common refrigerants such as HFC, FC or CFC with a sensitivity of less than 4g/a (grams per year) even in the smallest quantities and thus detect leaks in a system. If the device detects a leak, it immediately triggers both a visual and an acoustic alarm.

The testo 316-3 meets the requirements of the F-Gas regulation as well as the standards SAE J1627 and EN 14624:2012. In combination with a battery life of 16 hours and a service life of the sensor of around one year, the leak detector is ideally suited for use in refrigeration and heating technology.

Longer service life for the heat pump – check the electrical system

So that a heat pump not only works efficiently but also safely, it is essential to measure the important electrical parameters such as current, voltage or resistance professionally. With the state-of-the-art testo 760-1 digital multimeter, you are well equipped for every measurement. The device automatically recognizes the appropriate measured variable based on the socket assignment, so that life-threatening incorrect settings can be ruled out.

Due to the large illuminated display and function keys, the multimeter can also be operated with one hand and also has all the important measuring functions – from voltage measurement to ionization current. You can hand over the heat pump and the heating system to the operator with a clear conscience after (re)commissioning.

Conclusion

Against the background of climate change, heat pumps are becoming increasingly important in everyday use. Hardly any new building receives subsidies these days if it is not based on an environmentally friendly heating system. Heat pumps can also cool or, if necessary, heat tap water. In addition to proper operation, regular maintenance is essential so that they can fully develop their potential and thus not only help the operator’s wallet in the best possible way, but also the environment. With the measuring instruments from testo, you can ensure that tested systems work as desired.