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Close Control Air Conditioning Equipment

1.1   Scope

Close control air conditioning equipment is used to control temperature (and optionally humidity) in rooms and enclosures containing heat generating equipment, such as servers, computers or telecommunications devices, and in some types of manufacturing process (e.g. clean rooms). The equipment typically operates continuously and has a much higher unit floor area cooling load requirement than conventional air conditioning.

Close control air conditioning equipment is available with a wide variety of efficiencies. The Energy Technology List (ETL) Scheme aims to encourage the purchase of higher efficiency products.

The ETL Scheme covers seven categories of product:

  1. DX air cooled close control air conditioning equipment (without free cooling coil).
  2. DX air cooled close control air conditioning equipment with integral chilled water free cooling coil(s).
  3. DX water cooled close control air conditioning equipment (without free cooling coil).
  4. DX water cooled close control air conditioning equipment with integral chilled water free cooling coil(s).
  5. Chilled water (CHW) cooled close control air conditioning equipment.
  6. Dual mode: DX air cooled and chilled water (CHW) cooled close control air conditioning equipment (without free cooling).
  7. Dual mode: DX water cooled and chilled water (CHW) cooled close control air conditioning equipment (without free cooling).

Where DX stands for ‘direct expansion’ and refers to products that effect cooling, or partial cooling, of the air by evaporating a refrigerant in their indoor heat exchangers.

The ETL Scheme covers products that are designed to provide close control air conditioning to the room containing the heat generating equipment (room air conditioning, or room AC, products) and those that are designed to provide close control air conditioning to the local area surrounding the heat generating equipment or the heat generating equipment itself (close coupled cooling, or CCC, products).

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

1.2   Definitions

Close control air conditioning equipment covers products that are specifically designed to provide the cooling needed to maintain the air temperature, and optionally the relative humidity, in rooms that contain equipment or processes with high sensible heat loads.

1.3   Requirements

1.3.1    Eligibility requirements  

To be eligible, products must:

  • Either be a single packaged unit or consist of two or more factory built sub-assemblies that are designed to be connected together during installation.
  • Either incorporate an electrically powered compressor (or compressors) and / or incorporate a chilled water cooling coil with fittings for connection to an external chilled water circuit.
  • Have a ratio of sensible cooling capacity to the total cooling capacity (i.e. sensible heat ratio) that is greater than or equal to (>=) 0.9 at the relevant rating conditions specified in Table 1.2 and Table 1.3 below.
  • Have an appropriate Conformity Assessment mark.

1.3.2    Performance requirements 

Products must have an energy efficiency ratio (EER), and a free cooling capacity (where applicable) that is greater than or equal to the values set out in Table 1.1 below.

Table 1.1    Performance thresholds for close control air conditioning equipment

 

 

Product category

EER

Free cooling capacity

1.

DX air cooled (without free cooling).

≥  3.20

 

2.

DX air cooled with integral chilled water free cooling coil(s).

≥  3.00

Free cooling coil cooling capacity >= 90% of cooling capacity in DX operating mode where both cooling capacities are measured at the rating conditions given in Table 1.2 for room AC products and Table 1.3 for CCC products.

3.

DX water cooled (without free cooling).

≥  3.90

 

4.

DX water cooled with integral chilled water free cooling coil(s).

≥  3.60

Free cooling coil cooling >= 90% of cooling capacity in DX operating mode where both cooling capacities are measured at the rating conditions given in Table 1.2 for room AC products and Table 1.3 for CCC products.

5.

Chilled water (CHW) cooled (only).

≥  18.00

 

6.

Dual mode: DX air cooled and chilled water cooled (without free cooling)

DX mode

≥  3.20

 

CHW mode

≥  18.00

 

7

Dual mode: DX water cooled and chilled water cooled (without free cooling)

DX mode

≥  3.90

 

CHW mode

≥  18.00

 

'≥' means ‘greater than or equal to’.


Where EER is the ratio of total gross cooling capacity (Watts) to the electric power absorbed by the product (Pelec). In the case of DX and dual mode products, the electric power absorbed by the product should include that of both the indoor and outdoor heat exchangers.

1.4    Measurement and Calculations

1.4.1    Measurement Standards and Test Requirements

All room AC products must be tested in accordance with the test standards, procedures and conditions specified in Table 1.2. All CCC products must be tested in accordance with the test standards, procedures and conditions specified in Table 1.3.
 

Table 1.2 Required test procedures for room AC close control air conditioning equipment

Product category Standard Rating condition
DX air cooled (without free cooling). BS EN 14511:2013 Outdoor heat exchanger, inlet dry bulb temperature 35°C Indoor heat exchanger, inlet dry bulb temperature 23.9°C and inlet wet bulb temperature 16.2°C
DX air cooled with integral chilled water free cooling coil(s). DX refrigeration part BS EN 14511:2013 Outdoor heat exchanger, inlet dry bulb temperature 35°C Indoor heat exchanger, inlet dry bulb temperature 23.9°C and inlet wet bulb temperature 16.2°C
Free cooling coil BS 4856-3:1975 (if ducted) BS 4856-2:1975 (if not ducted) or BS EN 1397: 2015 Liquid side conditions, inlet temperature 10°C and outlet 16.7°C Indoor heat exchanger, inlet dry bulb temperature 23.9°C and inlet wet bulb temperature 16.2°C
DX water cooled (without free cooling). BS EN 14511:2013 Outdoor heat exchanger, inlet temperature 28.3°C and outlet temperature 35°C Indoor heat exchanger, inlet dry bulb temperature 23.9°C and inlet wet bulb temperature 16.2°C
DX water cooled with integral chilled water free cooling coil(s). DX refrigeration part BS EN 14511:2013 Outdoor heat exchanger, inlet temperature 28.3°C and outlet temperature 35°C Indoor heat exchanger, inlet dry bulb temperature 23.9°C and inlet wet bulb temperature 16.2°C
Free cooling coil BS 4856-3:1975 (if ducted) BS 4856-2:1975 (if not ducted) or BS EN 1397:2015 Liquid side conditions, inlet temperature 10°C and outlet 16.7°C Indoor heat exchanger, inlet dry bulb temperature 23.9°C and inlet wet bulb temperature 16.2°C
Chilled water (CHW) cooled (only). BS 4856-3:1975 (if ducted) BS 4856-2:1975 (if not ducted) or BS EN 1397:2015 Liquid side conditions, inlet temperature 10°C and outlet 16.7°C Indoor heat exchanger, inlet dry bulb temperature 23.9°C and inlet wet bulb temperature 16.2°C
Dual mode: DX air cooled and chilled water   cooling (without free cooling). DX mode BS EN 14511:2013 Outdoor heat exchanger, inlet dry bulb temperature 35°C Indoor heat exchanger, inlet dry bulb temperature 23.9°C and inlet wet bulb temperature 16.2°C
CHW mode BS 4856-3:1975 (if ducted) BS 4856-2:1975 (if not ducted) or BS EN 1397:2015 Liquid side conditions, inlet temperature 10°C and outlet 16.7°C Indoor heat exchanger, inlet dry bulb temperature 23.9°C and inlet wet bulb temperature 16.2°C
Dual mode: DX water cooled and chilled water cooling (without free cooling). DX mode BS EN 14511:2013 Outdoor heat exchanger, inlet temperature 28.3°C and outlet temperature 35°C Indoor heat exchanger, inlet dry bulb temperature 23.9°C and inlet wet bulb temperature 16.2°C
CHW mode BS 4856-3:1975 (if ducted) BS 4856-2:1975 (if not ducted) or BS EN 1397:2015 Liquid side conditions, inlet temperature 10°C and outlet 16.7°C Indoor heat exchanger, inlet dry bulb temperature 23.9°C and inlet wet bulb temperature 16.2°C


Table 1.3    Required test procedures for CCC close control air conditioning equipment

  Product category Standard Rating condition
1. DX air cooled (without free cooling). BS EN 14511:2013 Outdoor heat exchanger, inlet dry bulb temperature 35°C Indoor heat exchanger, inlet dry bulb temperature 35.0°C and inlet wet bulb temperature 19.9°C
2. DX air cooled with integral chilled water free cooling coil(s). DX refrigeration part BS EN 14511:2013 Outdoor heat exchanger, inlet dry bulb temperature 35°C Indoor heat exchanger, inlet dry bulb temperature 35.0°C and inlet wet bulb temperature 19.9°C
Free cooling coil BS 4856-3:1975 (if ducted) BS 4856-2:1975 (if not ducted) or BS EN 1397:2015 Liquid side conditions, inlet temperature 10°C and outlet 16.7°C Indoor heat exchanger, inlet dry bulb temperature 35.0°C and inlet wet bulb temperature 19.9°C
3. DX water cooled (without free cooling). BS EN 14511:2013 Outdoor heat exchanger, inlet temperature 28.3°C and outlet temperature 35°C Indoor heat exchanger, inlet dry bulb temperature 35.0°C and inlet wet bulb temperature 19.9°C
4. DX water cooled with integral chilled water free cooling coil(s). DX refrigeration part BS EN 14511:2013 Outdoor heat exchanger, inlet temperature 28.3°C and outlet temperature 35°C Indoor heat exchanger, inlet dry bulb temperature 35.0°C and inlet wet bulb temperature 19.9°C
Free cooling coil BS 4856-3:1975 (if ducted) BS 4856-2:1975 (if not ducted) or BS EN 1397:2015 Liquid side conditions, inlet temperature 10°C and outlet 16.7°C Indoor heat exchanger, inlet dry bulb temperature 35.0°C and inlet wet bulb temperature 19.9°C
5. Chilled water (CHW) cooled (only). BS 4856-3:1975 (if ducted) BS 4856-2:1975 (if not ducted) or BS EN 1397:2015 Liquid side conditions, inlet temperature 10°C and outlet 16.7°C Indoor heat exchanger, inlet dry bulb temperature 35.0°C and inlet wet bulb temperature 19.9°C
6. Dual mode: DX air cooled and chilled water cooling   (without free cooling). DX mode BS EN 14511:2013 Outdoor heat exchanger, inlet dry bulb temperature 35°C Indoor heat exchanger, inlet dry bulb temperature 35.0°C and inlet wet bulb temperature 19.9°C
CHW mode BS 4856-3:1975 (if ducted) BS 4856-2:1975 (if not ducted) or BS EN 1397:2015 Liquid side conditions, inlet temperature 10°C and outlet 16.7°C Indoor heat exchanger, inlet dry bulb temperature 35.0°C and inlet wet bulb temperature 19.9°C
7. Dual mode: DX water cooled and chilled water cooling (without free cooling). DX mode BS EN 14511:2013 Outdoor heat exchanger, inlet temperature 28.3°C and outlet temperature 35°C Indoor heat exchanger, inlet dry bulb temperature 35.0°C and inlet wet bulb temperature 19.9°C
CHW mode BS 4856-3:1975 (if ducted) BS 4856-2:1975 (if not ducted) or BS EN 1397:2015 Liquid side conditions, inlet temperature 10°C and outlet 16.7°C Indoor heat exchanger, inlet dry bulb temperature 35.0°C and inlet wet bulb temperature 19.9°C

An external static pressure of at least (≥) 20 Pascals must be used for testing downflow units with ducted outlets.

Please note that performance data obtained in accordance with the corresponding procedures and the standard rating conditions for Close Control laid down in BS EN 14511:2007 or BS EN 14511:2011 will be accepted as an alternative to testing in accordance with BS EN 14511:2013 and the rating conditions given in Table 1.2 and Table 1.3 until further notice.

Please note that performance data obtained in accordance with the corresponding procedures laid down in BS EN 1397:1999 will be accepted as an alternative to testing in accordance with BS EN 1397:2015 until further notice.

1.4.2    Rounding  

For the avoidance of doubt test data should be presented to 2 decimal places. As an example an EER of 3.19 for a DX air cooled product would be deemed a fail.

1.5   Verification for ETL Listing 

Any of the following testing routes may be used to demonstrate the conformity of products against the requirements:

  • 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 . 

1.5.1    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 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.
  • Fit within the same product category (e.g. are all DX air cooled without free cooling).
  • Use the same indoor heat exchanger configuration (e.g. 4-row and fan blow through).

The representative models must be selected by dividing the range of products into groups of models with similar design characteristics, and testing a model in the lowest quartile of predicted performance in each group. The performance of each model in the group must be predicted using a validated mathematical model. As a minimum, at least two models must be tested in each range of products.

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.