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Radiant Heating Equipment

1.1    Scope

Radiant heating equipment covers products that are specifically designed to heat people or objects in the space below them by infrared radiation without heating the surrounding air directly, and optimising controllers that ensure radiant heating systems operate in an efficient manner.

1.2    Definitions

Radiant heaters are widely used to provide space heating for warehouses, retail sheds, sports centres, factories, and other buildings containing similarly large spaces. Radiant heaters contain a gas or oil-fired burner that is used to heat a tube, cone or plaque that emits infrared radiation when hot. This infrared radiation is focussed and directed downwards by reflectors within the product.

Radiant heaters are available in a range of different types and efficiencies. The Energy Technology List (ETL) Scheme encourages the purchase of higher efficiency radiant heaters. It also encourages the purchase of optimising controllers that ensure that radiant heating products and systems operate in an energy efficient manner that reflects weather conditions, occupation schedules and user requirements.

The ETL Scheme covers five categories of product:

  1. Unitary radiant tube heater units and packages.
  2. Multi burner radiant tube heater units and packages.
  3. Continuous radiant tube heater units and packages.
  4. Radiant plaque and cone heater units and packages.
  5. Optimising controllers for radiant heating systems. (including both standalone unit and add-on module type products).

Where packages consist of a combination of radiant heater units, and an optimising controller.

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

1.3    Requirements

1.3.1       Eligibility requirements

To be eligible, all products shall comply with the relevant requirements set out below:

  1. All products incorporating radiant heaters shall:
     - Be gas or oil-fired
     - Be designed to be permanently mounted above head height.
     - Have an appropriate Conformity Assessment mark.
  2. All products incorporating radiant tube type heaters shall incorporate a reflector (with end caps) that directs the radiated heat downwards.
  3. All products that incorporate optimising controllers shall:
     - Incorporate a microprocessor based controller that is pre-programmed to:
       a)    Automatically control the temperature in one or more zones within a building in an energy efficient manner that reflects predefined zone occupation schedules
       b)    Automatically switch radiant heating equipment on and off in accordance with the predefined occupation schedule for each of the zones being controlled.
     - Incorporate the following automatic control mechanisms:
       a)    A frost protection mechanism that monitors internal air temperature, and switches on the radiant heaters to prevent equipment and/or pipework from freezing up.
       b)    A building fabric protection mechanism that monitors external or internal temperatures and switches heating on to prevent condensation from occurring.
       c)    An anti-tampering mechanism that prevents the product’s control strategy from being modified, and the specified automatic control mechanisms from being disabled, except during commissioning, maintenance or testing.
     - Provide facilities that enable building managers to:
       d)    Define the normal occupation times for the building and for each zone controlled (in intervals of five minutes or less), for each day of the week, including at least two periods of occupation per day (i.e. at least 14 different occupation periods per week).
       e)    Define the temperature set-points for each zone to ±1°C.
     - Provide facilities that enable building users to “temporarily override” the pre-set times when the radiant heating is scheduled to be switched off within an individual zone.
     - Incorporate, or be packaged with, a black bulb sensor.
     - Conform with the requirements of The Electromagnetic Compatibility Regulations 2016 or have an appropriate Conformity Assessment mark.

Where:

  • A mechanism is defined as “any sequence of pre-defined actions that performs a given function, where an action can be defined in hardware and/or software terms”.
  • Products that incorporate control strategies that are specifically designed to control other types of equipment (other than warm air or radiant heaters) are not eligible.

 

1.3.2       Performance requirements

All products that incorporate radiant heaters shall have a seasonal space heating energy efficiency (ηS) that is greater than or equal to the values set out in Table 1.1 below.

Table 1.1  Performance requirements for radiant heating equipment.

 

Product category

Seasonal space heating energy efficiency (ηS)
%

1.

Unitary radiant tube heater units and packages.

≥ 80.0%

2.

Multi burner radiant tube heater units and packages.

≥ 80.0%

3.

Continuous radiant tube heater units and packages.

≥ 90.0%

4.

Radiant plaque and cone heater units and packages.

≥ 88.0%

"≥" means "greater than or equal to"

1.4    Measurement and Calculations

1.4.1       Measurement standards

The seasonal space heating energy efficiency of the product shall be determined in accordance with the procedure and test conditions set out in: 

  • Commission Regulation (EU) 2015/1188 implementing Directive 2009/125/EC of the European Parliament and of the Council with regard to Ecodesign requirements for local space heaters.

The emission efficiency associated with the radiant heating component of continuous radiant heating systems shall be determined in accordance with the relevant procedures and test conditions in the following standard:

  • prEN 17175: 2017, “Gas-fired overhead radiant strip heaters and multi-burner continuous radiant tube heater systems for non-domestic use - Safety and energy efficiency”.

1.4.2       Performance metric

The seasonal space heating energy efficiency for the product shall be calculated using the equation below:

$$η_S=η_S,on-F(1)-F(4)-F(5)$$

Where:

  • ηS,on is the seasonal space heating energy efficiency in active mode, expressed in %.
    $$η_(S,on)=η_(S,th)∙η_(S,RF)$$
  • ηS,th is the weighted thermal efficiency and ηS,RF is the emission efficiency, both of which shall be determined in accordance with Annex III, point 5(b) of Commission Regulation (EU) 2015/1188 for commercial local space heaters.
  • F(1) is a correction factor accounting for a negative contribution to seasonal space heating efficiency for commercial local space heaters due to adjusted contributions for options for the heat output, expressed in %. The value for this shall be determined in accordance with Table 6 of Commission Regulation (EU) 2015/1188.
  • F(4) is  a correction factor accounting for a negative contribution to the seasonal space heating energy efficiency by auxiliary electricity consumption, expressed in %. The value for this shall be determined in accordance with Annex III, point 5(f) of Commission Regulation (EU) 2015/1188 for commercial local space heaters.
  • F(5) is a correction factor accounting for a negative contribution to the seasonal space heating energy efficiency by energy consumption of a permanent pilot flame, expressed in %. The value for this shall be determined in accordance with Annex III, point 5(g) of Commission Regulation (EU) 2015/1188 for commercial local space heaters.

1.4.3       Test requirements

The product shall be tested with the minimum possible length of flue that is consistent with the product’s design specification. Where the product is supplied in several parts that are to be connected together during installation, the product shall be tested with the minimum possible interconnecting pipework.

1.4.4       Rounding 

For the avoidance of doubt, efficiency test data shall be presented to 1 decimal place. As an example, a unitary radiant tube heater with a seasonal space heating energy efficiency of 79.9% would be deemed to not meet the performance requirements.

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 framework1.

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 fuel (e.g. oil or gas) as the representative model.
  • Fit within the same product category (e.g. are all unitary radiant tube heater units) as the representative model.

The representative models shall be selected by dividing the range of products into groups of models with similar characteristics, as above, and testing a model in each group. The performance of each model in the group shall be predicted by extrapolation or interpolation or by using a validated mathematical model. As a minimum, a full test report shall be provided for at least one model tested in each range of products. Details of the calculation method used in determining the performance of models that have not been tested shall also be provided.

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

This specification is scheduled for review during the 2022/23 ETL review period.  

1.7.2       Illustrative future direction of the requirements 

A suite of provisional test standards has been introduced to enable performance measurement for the Ecodesign regulation for local space heaters. With the exception of the test standard for continuous radiant heating systems which previously did not exist, these provisional standards are not included in this specification. Future requirements will reference the finalised versions of the test standards when they come into force.

 

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