Glossary of Terms

This is a glossary of terms and abbreviations used by this website and within the industrial, commercial, agricultural, leisure heating industry.  The terms are listed apathetically.

Calorised Emitter Tubes

Is where aluminium is fused to the surface of base metal heating tubes to protect it from oxygen , carbon, sulphur and the products of combustion of all common fuels.  Due to the protection given to the base metal, calorised aluminised mild steel has improved resistance to deformation and scaling at elevated temperatures.  It also provides improved radiation performance.  (See “Why Calorised Emitter Tubes” for more details)

DECC – Department of Energy and Climate Change

DECC is a ministerial department that works to make sure the UK has secure, clean, affordable energy supplies.

ECA – Enhanced Capital Allowances

The ECA scheme means that a business can invest in energy-saving heating systems in a cost efficient manner. The first year allowances let businesses set 100% of the cost of the assets against taxable profits in a single tax year. This means the company can write off the cost of the new plant or machinery against the business’s taxable profits in the financial year the purchase was made.  An ECA is claimed through a business’s income or corporation tax return in the same way as any other capital allowance.


The EU’s Energy-Related Products Directive (ErP Directive 2009/125/EC) is an eco-design directive and applies to most products that consume energy throughout their lifecycle – from dishwashers to household electronics, to air conditioners, boilers and much more. The ErP directive is intended to encourage manufacturers and importers to provide consumers with products that are more energy efficient.

The scope of ErP certification involves testing a product to prove it consumes energy below agreed limits – once tested, a CE mark will be attached to the product, which permits its sale across the EU.


Testing a product to ensure compliance with the ErP directive provides access to the EU and European Economic Area’s 500 million consumers. Products bearing the CE mark are presumed compliant with the requirements of the ErP Directive and can therefore be freely sold anywhere in the bloc.

Complying with the EU’s ErP Directive is mandatory for all energy-using and energy-related products imported, marketed or sold in the EU – failing to do so can result in fines and product recalls.

From 01.01.2018, the ErP Directive also applies to building heating systems such as tube or luminous heaters [ENER / LOT 20 individual room heaters] as well as to hot air devices [ENER / LOT 21 hot air central heating systems without CHP]. The specific requirements for these product groups are laid down in Regulation [EU] 2015/1188.

Accordingly, the requirements for gas infrared heaters include:

The indicator for the annual efficiency of space heating is at least 74% for tube heaters. For luminous heaters, this value is at least 85%.

The NOx emissions for luminous and tube heaters: maximum 200 mg/kWh

ETL – Energy Technology List.

The ETL is managed on behalf of DECC by the Carbon Trust. The ETL is a government-managed list of energy-efficient heating system (and other plant machinery) that qualify for full tax relief. For a product to be on the ETL, it must meet specific energy-saving or energy-efficient criteria. The ETL is part of the Enhanced Capital Allowance (ECA) tax scheme for businesses.

Radiant Heating

Radiant heaters work in the same way as the sun.  Radiant heat is infra-red energy that passes through air and is converted into heat by solid objects that it comes into contact with.  All light energy is eventually converted into heat. Infra-red energy is just another form of light energy which we cannot see with the naked eye.  This form of heating provides instant heat without the need to heat the surrounding air first (like convection heater), it is silent and has low running and capital costs (when compared to other forms of heating with equivalent outputs).

Why do SPACE-RAY use Calorised Emitter tubes? The comparison tables below show the relative merits of emitter tube materials.

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