Water to Air Heat Pumps, Split, Multi-split and VRF

1.1           Scope

Water to Air Heat Pumps, Split, Multi-Split and VRF, are products that are specifically designed to transfer heat from water (in a building’s internal water loop) into the air within the space to be heated by means of a refrigeration cycle.

‘Split’ type heat pumps have separate heat collection and rejection units for each space known as ‘outdoor’ and ‘indoor’ units. The ‘outdoor’ and ‘indoor’ units are specifically designed to be connected together during installation by refrigerant pipework to form a single functional unit.

Variable refrigerant flow (VRF) heat pumps are specifically designed to automatically adjust the flow of refrigerant to each indoor unit so that the heat delivered is matched to the demand.

1.2           Definitions

Water to Air Heat Pumps, Split, Multi-Split and VRF, use an electrically operated refrigeration system to transfer heat from an internal water loop into the air within the space to be heated. They can be used to provide space heating in a wide range of buildings and some products also are able to provide cooling by reversing the refrigeration cycle within the product (these products are known as reversible ‘water cooled’ air conditioning units).

Water to Air Heat Pumps, Split, Multi-Split and VRF are available with a range of efficiencies. The Energy Technology List (ETL) Scheme aims to encourage the purchase of higher efficiency products.

The ETL Scheme covers two categories of products:

1.     Single split (non-VRF) heat pumps that consist of one ‘outdoor’ unit and one ‘indoor’ unit

2.     Multi-split VRF heat pumps that consist of one ‘outdoor’ unit connected to one or more ‘indoor’ units using a common refrigerant circuit with the indoor units individually controlled.

1.3           Requirements

1.3.1       Eligibility requirements

To be eligible for inclusion on the ETL, products shall meet the requirements as set out below.

To be eligible, products shall:

• Consist of an ‘outdoor’ unit and one or more ‘indoor’ units that are:
  • Factory–built sub-assemblies.
  • Supplied as a matched set of units.
  • Designed to be connected together during installation.
• Incorporate an electrically driven refrigeration system.
• Be designed for, and include fittings for, permanent installation.
• Have an appropriate Conformity Assessment mark.

1.3.2       Performance requirements

Eligible products shall meet the performance criteria set out in Table 1.1 below for:

• Seasonal Space Heating Energy Efficiency for water heat source, as defined by Ecodesign Commission Regulation (EU) 2016/2281
• Seasonal Space Cooling Energy Efficiency for ground coupled heat sink, as defined by Ecodesign Commission Regulation (EU) 2016/2281

Table 1.1  Performance thresholds for water to air heat pumps, split, multi-split & VRF

"≥" means "greater than"

1.4           Measurement and Calculations

1.4.1       Energy efficiency metrics

Seasonal Space Heating Efficiency (η_s,h) – ratio between the space heating demand for reference heating season, supplied by a space heater and the annual primary energy consumption required to meet this demand (as defined by Ecodesign Commission Regulation (EU) 2016/2281).

Seasonal Space Cooling Energy Efficiency (η_s,c) – ratio between the space cooling demand for reference cooling season supplied and annual primary energy consumption required to meet that demand

Seasonal Coefficient Of Performance (SCOP) – overall coefficient of performance of a heat pump using electricity, representative of the heating season, calculated as the reference annual heating demand divided by annual energy consumption for heating (as defined by Ecodesign Commission Regulation (EU) 2016/2281).

Seasonal Energy Efficiency Ratio (SEER) – overall energy efficiency ratio of a heat pump working in reverse mode for a representative cooling season, calculated as the reference annual cooling demand divided by the annual energy consumption for cooling (as defined by Ecodesign Commission Regulation (EU) 2016/2281).

Primary energy consumption for electricity usage is obtained using Conversion Coefficient (CC), known also as Primary Energy Factor, equal to 2.5, as defined by Ecodesign Commission Regulation (EU) 2016/2281.

Reference heating season, called also climate - set of operating conditions describing per bin the combination of outdoor temperatures and the number of hours these temperatures occur for heating for which the unit is declared fit for purpose There are three reference heating seasons: “A” average, “C” colder and “W” warmer. UK is located in two reference zones: A and W, but for the ETL purposes “A” for average is to be used.

Correction factor (F1) is correction that accounts for a negative contribution to the seasonal space heating energy efficiency of heaters due to adjusted contributions of temperature controls, equal to 3% (BS EN 14825:2016)

In case of any changes regarding the value of CC in relevant regulations or test reporting procedures, performance indicators will be calculated using following equations:

(1)   η_s,h= SCOP/CC -F1

(2)   η_s,c= SEER/CC -F1

1.4.2       Test Requirements

No additional testing requirements beyond the measurement standard below

1.4.3       Measurement standards

All products shall be tested in accordance with the procedures in Commission Regulation (EU) No 2281/2016, consistent with BS EN 14825:2016. The standard rating conditions are set out in the Table 1.2 below.

Table 1.2    Test conditions for water to air heat pumps, split, multi-split and VRF

Please note that performance data obtained in accordance with the corresponding procedures and standard rating conditions laid down in BS EN 14825: 2013 will be accepted as an alternative to testing in accordance with BS EN 14825: 2016 until further notice.

1.4.4       Rounding 

For the avoidance of doubt test data should be presented to three significant figures. As an example, a multi-split VRF heat pump with a heating mode η_s,h of 169.4% would be deemed to be a fail.

1.5           Verification for ETL Listing

There are five main ways that applicants can demonstrate their product’s performance:

• In-house testing – Self-certified
• In-house testing – Self-tested and verified or cross-checked by an independent body
• Witnessed testing
• Independent testing
• Representative testing (see clause 1.5.1)

Further information regarding the first four routes can be found in Guidance Note 5 on the ETL product testing framework[1].

1.5.1       Representative Testing

Where applications are being made for a range of products that are variants of the same basic design, test data may be submitted for a representative model, provided that all variants, i.e. models, share following characteristic features:

• Use the same refrigerant
• Have the same compressor type (i.e. manufacturer, line of models), which should imply:
  • same method of compression (e.g. reciprocating or scroll) and
  • same type of enclosure (e.g. hermetic or semi-hermetic)
• Use the same defrosting method (e.g. hot gas defrost)
• Fit within the same product category (i.e. are all low-temperature air to water heat pumps, or are all non-low-temperature air to water heat pumps.
• The representative models may be selected by dividing the range of products into groups of models with similar design characteristics. The performance of each model shall be predicted using a validated mathematical model. At least one model in each group shall be tested for validation purposes. A report documenting performed model calculations, showing all significant calculation steps, shall be submitted with the application.

It should be noted that:

• If a manufacturer voluntarily removes the representative model from the ETL then other products linked with that representative model may or may not be permitted to remain on the ETL.
• If any product submitted under these representative model rules is later found not to meet the performance criteria when independently tested, then all products based on the same representative model will be removed from the ETL.

1.6           Conformity testing

Products listed on the ETL may be subject to the scheme’s conformity testing programme in order to ensure listed models continue to meet the ETL requirements.

1.7           Review

1.7.1       Indicative review date

The next technical review is scheduled for 2022-23.

1.7.2       Illustrative future direction of the requirements 

Future changes to the Specification may include:

• Increasing performance thresholds for η_s,h and η_s,h
• Introduction of refrigerant GWP requirements.

[1] https://www.gov.uk/government/publications/energy-technology-list-etl-product-testing-framework