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Heating & Ventilation

Low surface temperature radiators


Stelrad Radiators offers a choice of CPDs. One of the most popular to date is its CPD on low surface temperature radiators.

The aims and learning outcomes of this CPD presentation from Stelrad Radiators are to provide guidance on the use of Low Surface Temperature steel panel emitters to avoid radiator burns and for safe room heating with particular reference to the way radiators actually work and the different types available, the requirement for safe heating in public, healthcare and education applications and the relevant regulations and standards. Also to raise awareness of low surface temperature radiators – LST – technology which provides safe space heating in education and healthcare and other public buildings.

This is a very much shortened version of the actual CPD programme but covers the key area of LST radiators without covering the full story about radiators per se. The full presentation is available from Stelrad which gives significantly more information.

First principles
Radiators are metal vessels that allow hot water to circulate through them, emitting warmth to the surroundings. A radiator consists of a sealed hollow metal container filled with hot water. As it gives out heat, the hot water cools and drops to the bottom of the radiator and is forced out of an exit pipe.

Because water has a specific heat-value, a hot water radiator can be specified and sized to correctly replace the room’s heat loss and maintain a required level of thermal comfort.

Hot water for the emitter is generated in a boiler, and circulated by pumps through emitters within the building. The temperature of the surface of the radiator depends on the settings of the boiler. The surface can get up to around 70°C if not controlled. That is hot enough to cause an injury. And that is why we need to discuss low surface temperature radiators.

There are four main types of radiator: the single panel, available with or without convector fins known as either P1 without fins or K1 with fins. The double panel, available with either one set or with two sets of convector fins is known as either P+ with one set of fins or K2 with two sets of fins. The convector fins improve the heat output by convection. Radiators with convection fins will pass more heat into the room than those without. The double panel reduces the overall size of the emitter required, yet increases its heat output.r2

When water is in excess of 43 °C there is a high risk of burning from a dry surface and scalds from a liquid, and even fatalities to the elderly, people with mental illness or learning disabilities and children who cannot react appropriately or quickly enough to prevent injury. Burns will result if naked skin is held against the hot surface for any length of time. At a water temperature of 70°C, people will receive partial thickness skin burns in approximately 0.7 of one second – and full thickness burns in 10 seconds.

According to the annual Leisure Accident Surveillance System (funded by the Department of Trade and Industry and managed by the Royal Society for the Prevention of Accidents) 1,970 people were injured in a public building by either a radiator or hot pipework over a 12 month period, while 71% of these accidents occurred in a place of education and all were serious enough to warrant a hospital visit.

It is important to say that these accidents were preventable. The wrong equipment was specified. Low surface temperature radiators prevent injuries like this.

Let’s look first at the risks.

RISKS in hospitals
Any hospital, open to use by the public (NHS or private establishments) has a Duty of Care to ensure that staff, patients and visitors are not exposed to unnecessary risk from heat emitters. There should be no exposed hot surfaces which can cause burns.

RISKS in nursing and care homes
Individuals who have limited movement and who cannot move away from the heat emitter quickly enough can sustain burns. This often occurs because they have fallen and are physically unable to move due to their mobility or are trapped by the furniture arrangement. Incidents often occur in areas where there is not a regular flow of staff or others to raise the alarm, eg in bedrooms (especially during the night), bathrooms, and some lounges.

RISKS in education establishments
Very hot surfaces can cause burns to the vulnerable soft skin in young children. So risks that need to be assessed and minimised, in relation to heating systems, include exposure to hot surfaces on radiators and associated pipework and the danger of someone being injured by a sharp edge or corner. Energy efficiency, heating performance, aesthetics and ease of use also need to be considered.
Interestingly statistics related to injuries or deaths caused by hot surfaces are difficult to obtain but RIDDOR (Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995) does ensure that injuries are, at least, reported. For the period April 2001 to March 2006 RIDDOR statistics identified 2 fatal incidents and at least 5 major injuries attributable to burns from hot surfaces in health and social care premises.

Regulations for hot surfaces are governed by two major bodies. The NHS – National Health Service – covers its own estates. The HSE – Heath and Safety Executive – covers working environments. The HSE’s job is to prevent people being killed, injured or made ill by work. This covers burning risks from hot surfaces in health and social care.

For the NHS, The NHS Estates Health Guidance Notes – DN4 is the key document. These guidance notes for professionals cover “Safe hot water and surface temperatures”. This booklet was issued following a number of serious accidents, some of which proved fatal. The maximum surface temperature recommended in the Guidance Notes should not exceed 43°C.

The HSE oversees the relevant legislation which is The Health and Safety at Work Act 1974. HSE and Local Authority inspectors enforce these requirements. And this covers burning risks from hot surfaces in health and social care – i.e. Residential Homes. So the health and safety of people who use care services is covered by the general requirements of Section 3 of the Health and Safety at Work Act 1974 and by the risk assessment requirements of the Management of Health and Safety at Work Regulations.

Specific and individual requirements in Scotland and Wales are covered by their own legislation but all to the same effect.

So what is the safe surface temperature that we are working to? Its 43° C. Control measures by the HSE say that the maximum surface temperature of space heating devices should not exceed 43 °C, when the system is operating at the maximum design output. And that ‘other design solutions which ensure that the maximum surface temperature does not exceed 43 °C are also acceptable.’ This is the temperature which tests have shown to be the safest – such that if someone fell against the LST radiator and was stranded in that position for a very long time, no harm would be done to the skin. It is the same safe temperature required for hot water flowing from taps in public situations. (In that case a thermostatic valve is used to control the temperature).r3

Specially designed and purpose-built Low Surface Temperature radiators are designed to provide a safe, cool-touch solution to heating a building and this is the most practical way to prevent people from coming into direct contact with hot surfaces.

An LST is an emitter within a specially designed outer case, the surface of which at any point on its surface, never gets hotter than 43°C. The case is effectively built around a standard heat emitter. The emitter still radiates and still convects heat. The emitter does its job to heat the room but the case gets no hotter than 43°C. Convection plays a very important and safe role. It is the air gap between the emitter and the surface of the case which solves the problem and prevents the metal surface becoming too hot.

A number of models of LSTs are available in the market. Some consist simply of the emitter and its case. Some for added convenience for the installer consist of the emitter and its case, plus a built-in or factory fitted thermostatic valve (operated from the top platform of the case) and factory-fitted copper connecting pipes. Installation is made easier and quicker. And for some situations vertical models are more suitable. Here the position of the thermostat control should be at about waist height – 0.9 metres off the floor – positioned left or right handed.
BSEN442 is the British Standard test for heat output – it requires that water enters and leaves the radiator at definite temperatures. Flow into the radiator will be at 75°C. RETURN out (from) the radiator will be at 65°C. And the room temperature will be at a steady 20°C.

Installation is usually straightforward and good installers accustomed to fitting standard radiators will have no problems fitting LSTs. Some models are easier than others – depending on their configuration and state of factory fitted components. This article does not include a detailed installation guide – this is available fromStelrad if required.

Most appropriate use for LSTs is in Healthcare, Retirement homes, Care homes, Nursing homes, and all levels of education, especially pre-school nurseries. And for some new-build or refurbishment projects. LSTs can be used in any situation.

The main point about radiators are they are value for money solutions. They are easy to install with tried and tested technology – plumbers know them – and they are simple to maintain.

We hope this article will help you to apply the improved knowledge of LST radiators and to confidently specify the product to provide safe heating in public buildings.

And you should feel more confident about what products are available and how they help you conform with the regulations.

To get more information about the subject in this CPD there are a number of publications you could look at.

  • NHS Estates Health Guidance Note – ‘Safe’ hot water and surface temperatures’. This is available via the NHS Knowledge Information Portal
  • From the HSE there is Health and Safety in Care Homes – from HSE Books HSG220, 2001.
  • You may also be interested in these British and European standards. BS EN 442-1:1996 and BS 7593:2006

To arrange for this CPD to be given at your premises, call the Stelrad team on 01709 578950.