Accredited heat pump testing – benefits for manufacturers and users

The national heat pump market has recorded multi-year growth. Given strong investor interest, this trend is very likely to continue in the coming years as well. The following tendencies are currently observed:

• air is and will in the near future remain the dominant low-temperature heat source for heat pumps
• the fastest-growing segment of the heat pump market is pumps dedicated to domestic hot water (double-digit growth is recorded in this category).
• interest is growing in high-capacity heat pumps for commercial, industrial and district heating applications. These pumps usually use geothermal or hydrothermal energy.

Everything indicates that this trend will continue, also due to a number of subsidy programmes supporting initiatives that help reduce air pollution. Heat pumps fit such projects perfectly, but they must be characterised by performance coefficients at a suitably high level.

COP, SCOP, ηs coefficients

The basic coefficients characterising the energy efficiency of heat pumps are the COP, SCOP and ηs coefficients.

COP expresses the ratio of useful heat energy obtained to electrical energy input under specific system operating conditions. The value of this coefficient is determined on the basis of laboratory tests under conditions consistent with applicable standards. Application of standards objectifies the assessment of equipment and makes it possible to compare parameters (heating capacity, energy consumption, COP) of different heat pumps under the same operating conditions. COP depends very strongly on these conditions, so it is worth checking whether the manufacturer, when presenting data in catalogues, provides a full product characteristic or limits itself to publishing a COP value determined under the most favourable conditions. Tests performed in accordance with the appropriate standard will allow the user to avoid disappointment associated with low equipment efficiency and will protect the manufacturer against possible claims from users.

SCOP is the overall equipment performance coefficient for the entire heating season. SCOP expresses the ratio of annual heat demand to electricity consumption over the same period.

ηs seasonal space heating energy efficiency means, expressed in %, the ratio of space heating demand in a defined heating season to the annual energy consumption required to meet that demand.

Basic standards for heat pump testing

According to the definition contained in PN-EN 14511-1, a heat pump is an enclosed assembly or assemblies intended as a unit to supply heat. These units are equipped with electrically driven compressors.
For standardisation purposes the following types of heat pumps are distinguished:

– heat pumps with electrically driven compressors for space heating (SH) – PN-EN 14511
– heat pumps for domestic hot water preparation (DHW) – PN-EN 16147
– heat pumps with electrically driven compressors using ground as the low-temperature heat source with direct heat exchange from ground to water or brine (SH) – PN-EN 15879

Heat pump testing under standard conditions listed in PN-EN 14511

The authors of the standard distinguish two types of heat pump test conditions: standard rating conditions and application rating conditions.
Testing under standard rating conditions is the basic test.
In general, heat pump tests can be divided into several more important groups of tests. These are:

– Performance tests – covering determination of the energy characteristics
of the equipment under various standard conditions listed in the standard (heating capacity, cooling capacity, effective power input, COP and EER).
– Start-up and operating range tests,
– Equipment safety of use tests

Testing of heat pumps for domestic hot water preparation according to PN-EN 16147

A heat pump for domestic hot water preparation is, according to PN-EN 16147,
a heat pump defined in PN-EN 14511-1, connected to a hot water storage tank or with such a tank built in.
To determine its efficiency indicator, 10 different daily water draw-off profiles specified in the standard can be selected (3XS, XXS, XS, S, M, L, XL, XXL, 3XL, 4XL) for different storage heater capacities.
The scope of basic tests specified in the standard for the above heat pumps includes:

• Determination of heating capacity
• Determination of power input
• Determination of the energy efficiency coefficient COP
• Determination of the heating-up period
• Determination of power input in standby mode
• Determination of useful energy
• Determination of the reference hot water temperature and maximum domestic hot water volume

Testing of heat pumps with electrically driven compressors using ground as the low-temperature heat source with direct heat exchange from ground to water or brine according to PN-EN 15879-1

Heat pumps of this type are units consisting of a ground heat exchanger (built from a series of horizontal parallel loops) and a heat pump module. Heat is extracted by direct exchange with the ground by the refrigerant circulating in the circuit.
The scope of tests for the above heat pumps specified in the standard includes:

• Determination of heating capacity
• Determination of electrical power input
• Determination of the energy efficiency coefficient COP

Heat pump testing and assessment according to PN-EN 14825

The standard gives procedures for testing under part-load conditions and the methodology for calculating seasonal heat pump performance (the seasonal energy efficiency indicator ηs and the SCOP coefficient). These indicators are necessary to determine the energy class of equipment. It also covers methods for testing electricity consumption for various operating modes.

Energy labelling

The European Union has set ambitious environmental protection targets to be achieved by 2020, aiming for a significant increase in the use of renewable energy while reducing the share of primary energy and CO2 emissions. In the face of these issues the EU introduced the ErP Directive (2009/125/EC). Introduction of the Directive was intended to support and promote environmentally friendly projects that protect natural resources and reduce energy consumption. It results in the requirement to label heat sources of up to 70 kW and storage tanks of up to 500 l with an energy efficiency label.
For a space heating appliance to be marked with a seasonal energy efficiency class, it must be tested in a testing laboratory in order to determine the seasonal efficiency achieved (ɳs). Depending on the seasonal efficiency achieved by the appliance, a specific energy efficiency class from A+++ to G is assigned to it (Table 1). Heat pumps are among the most efficient heating appliances on the market. They may be marked with several different energy labels. However, all types must have a product (heat source) label containing information on seasonal energy efficiency class, energy demand and noise level. The label also includes a map dividing Europe into three different climate zones for which rated heating capacity values are determined. Requirements for energy labels for heat pumps are set out in Commission Regulation (EU) No 811/2013 of 18 February 2013. Energy labelling enables customers to make informed equipment choices on the basis of their energy consumption. Information on efficient and sustainable energy-related products significantly contributes to energy savings and lower energy bills, while promoting innovation and investment in manufacturing ever more energy-efficient products. Increasing the efficiency of energy-related products, achieved through informed customer choices and harmonisation of legislation at European Union level, brings benefits not only to consumers but also to manufacturers, industry and the economy as a whole.

Table 1. Seasonal space heating energy efficiency classes for low-temperature heat pumps and heat pump space heaters [Source: COMMISSION DELEGATED REGULATION (EU) No 811/2013 of 18 February 2013]

1. Supplier, trademark and model
2. Space heating
3. Space heating energy efficiency class
4. Energy efficiency class scale
5. Indoor sound power
6. Outdoor sound power
7. Declared water heating load profile
8. Water heating energy efficiency class
9. Rated heating capacity in different climate zones

1. Supplier, trademark
2. Space heating and hot water production energy efficiency class
3. Solar collector
4. Hot water storage tank
5. Temperature sensor
6. Supplementary heater
7. Heating
8. Package energy efficiency class
9. Energy efficiency class scale
10. Declared water heater load profile
11. Water heater energy efficiency class

Subsidies

Heat pumps use renewable energy sources, so support for their purchase and installation can be obtained from Provincial Funds for Environmental Protection and Water Management, e.g. preferential credit, a loan with partial write-off, co-financing of up to 80–100% of eligible costs. This applies to equipment holding a certificate issued by the appropriate accreditation body or an appropriate accredited testing laboratory confirming energy indicators.
An example is the recently announced “Clean Air” priority programme. The annex to the programme specifies technical requirements for heat pumps; among other things they must meet the requirements set out in Commission Delegated Regulation (EU) No 811/2013 of 18 February 2013 and in Regulation (EU) 2017/1369 of the European Parliament and of the Council of 4 July 2017 setting a framework for energy labelling and repealing Directive 2010/30/EU. Heat pumps must meet, with regard to space heating, energy efficiency class requirements of at least A+.

Benefits of accreditation

Accreditation brings benefits for all market participants. It is an essential tool in the process of deciding to purchase goods and services. Manufacturers can save time and money by choosing an accredited, and therefore competent, testing provider. Consumers receive reliable product information confirmed by an independent body. Tests performed by an accredited laboratory can facilitate access to export markets in Europe and worldwide. Certificates, test reports, calibration certificates and inspection reports issued by accredited certification, inspection and laboratory bodies may be recognised by interested institutions in countries that are signatories to multilateral agreements.

Central Refrigeration Centre COCH in Kraków is the only centre in Poland that performs accredited testing of heat pumps operating in air/water, water/water, brine/water systems, and with ground as the low-temperature heat source with direct heat exchange from ground to water or brine. Tests are carried out to establish energy and operating characteristics for factory-made equipment with integral or remote condensers, factory-made equipment with fixed or any form of capacity control, packaged self-contained units and packaged two- and multi-part units. The COCH laboratory performs refrigeration, air-conditioning and heat pump testing used, among other things, for assessing conformity with standards and directives.
Heat pump testing performed at COCH is covered by accreditation of the Polish testing laboratory system (Polish Centre for Accreditation accreditation No. AB 308) and by a licence to use the international ILAC MRA mark on mutual recognition of test reports issued by accredited laboratories worldwide.
We invite all interested parties to cooperate with us.

About the authors: Dorota Niedojadło, MSc Eng. – Head of the “COCH” Laboratory; Leszek Bednarczyk, MSc Eng. – Technical Manager of “COCH”; Bogdan Szczepański, MSc Eng. – Director of “COCH”