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Air Source: Gas Engine Driven Split and Multi-Split (including VRF) Heat Pumps

1.1           Scope

Air-source gas engine driven (GED) split and multi-split heat pumps use a gas-fired internal combustion engine driven refrigeration system to transfer heat from air outside a building to the air inside it. 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 flows around the product. (These products are known as reversible gas engine driven ‘air-cooled’ air conditioning units).

Air source gas engine driven split and multi-split heat pumps are available with a wide range of efficiencies. The Energy Technology List (ETL) Scheme aims to encourage the purchase of higher efficiency products.

The ETL Scheme covers four categories of products:

1.    Air source: GED single split (non-VRF) heat pumps that consist of one ‘outdoor’ unit and one ‘indoor’ unit.

2.    Air source: GED dual split (non-VRF) heat pumps that consist of one ‘outdoor’ unit and two ‘indoor’ units.

3.    Air source: GED multi-split (non-VRF) heat pumps that consist of one ‘outdoor’ unit connected to two or more ‘indoor’ units using either individual refrigerant circuits (with the indoor units individually controlled) or using a common refrigerant circuit with the indoor units controlled as one.

4.    Air source: GED split or multi-split variable refrigerant flow (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.

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

1.2           Definitions

Air-source, gas engine driven (GED), heat pumps covers products that are specifically designed to transfer heat from the air in one space to the air in another space by means of a refrigeration cycle that is driven by a gas-fired internal combustion engine.

‘Split’ type heat pumps have separate heat collection and rejection units for each space known as ‘indoor’ and ‘outdoor’ units. The ’indoor’ and ‘outdoor’ 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.

1.3           Requirements

1.3.1       Eligibility requirements 

To be eligible, products shall:

  • Consist of an ‘outdoor’ unit and one or more ‘indoor’ units that are:

a)    Factory–built sub-assemblies.

b)    Supplied as a matched set of units.

c)    Designed to be connected together during installation.

  • Incorporate a refrigeration system that is driven by a gas-fired internal combustion engine.
  • 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 Primary Energy Ratio in heating mode (SPERh) across the range of connected capacities and including 100% (full) load in heating mode.
  • Seasonal Primary Energy Ratio in cooling mode (SPERc) across the range of connected capacities and including 100% (full) load in cooling mode, where the product is designed to provide cooling.

Table 1.1    Performance requirements for air source: (GED) split and multi-split heat pumps ​​​​​

 

Product Category

Heating mode (SPERh)

Cooling mode (SPERc)

1.

Air source: GED single split (non VRF) heat pumps.

≥1.30

≥1.72

2.

Air source: GED dual split (non VRF) heat pumps.

≥1.30

≥1.72

3.

Air source: GED multi-split (non VRF) heat pumps.

≥1.30

≥1.72

4.

Air source: GED split and multi-split variable refrigerant flow (VRF) heat pumps.

≥1.30

≥1.72

"≥" means "greater than or equal to"

The performance requirements in Table 1.1 shall include all relevant energy inputs to the indoor unit(s) for the matched indoor and outdoor model assembly.

1.4           Measurement and Calculations

1.4.1       Measurement standards

All products shall be tested in accordance with the procedures laid down in the following standards:

■      BS EN 16905-3:2017, “Gas-fired endothermic engine driven heat pumps – Part 3: Test conditions”;

■      BS EN 16905-4:2017, “Gas-fired endothermic engine driven heat pumps – Part 4: Test methods”;

■      BS EN 16905-5:2017, “Gas-fired endothermic engine driven heat pumps – Part 5: Calculation of seasonal performances in heating and cooling mode”.

1.4.2       Test Requirements

The standard rating conditions are set out in the Table 1.2 below.

Table 1.2    Test conditions for air source: gas engine driven (GED) split and multi-split heat pumps

 

Product Category

Heating mode (SPERh)

Cooling mode (SPERc)

1.

Air source: GED single split (non-VRF) heat pumps.

BS EN 16905-3:2017

 Table 3

BS EN 16905-3:2017

Table 4

2.

Air source: GED dual split (non-VRF) heat pumps.

BS EN 16905-3:2017

 Table 3

BS EN 16905-3:2017

Table 4

3.

Air source: GED multi-split (non-VRF) heat pumps.

BS EN 16905-3:2017

Table 3

BS EN 16905-3:2017

Table 4

4.

Air source: GED split and multi-split variable refrigerant flow (VRF) heat pumps.

BS EN 16905-3:2017

Table 3

BS EN 16905-3:2017

Table 4

Notes

The heating standard test requires an entering air temperature on the indoor side of 20°C (Dry-bulb), and an entering air temperature on the outdoor side of 7°C (Dry-bulb) and 6°C (Wet-bulb).

The cooling standard test requires an entering air temperature on the indoor side of 27°C (Dry-bulb) and 19°C (Wet-bulb), and an entering air temperature on the outdoor side of 35°C (Dry-bulb).

1.4.3       Rounding 

For the avoidance of doubt test data should be presented to 2 decimal places. As an example, an air source gas engine driven single split (non-VRF) heat pump product with a heating mode SPERh of 1.29 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 two or more products that are variants of the same basic design, test data may be submitted for a representative selection of models, provided that all variants:

  • Use the same gas engine constructional design.
  • Use the same refrigerant as the representative model.
  • Have the same compressor type (i.e. manufacturer, method of compression (e.g. reciprocating or scroll) and type of enclosure (e.g. hermetic or semi-hermetic) as the representative model.
  • 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 air to water heat pumps (except low temperature heat pumps).
  • Use multiple indoor units with the same outdoor unit.

The representative models shall be selected by dividing the range of products into groups of models with similar design characteristics, and testing a model in each group.

As a minimum, at least one complete matched outdoor and indoor unit(s) model assembly shall be tested (as per the required test procedures listed above) in each range of products. Where other variants of indoor unit(s) are applied, the performance of each representative model assembly in the group may be calculated using a validated mathematical model.

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