One thing we have come to expect of radiators over the years is that they are pretty hot, but all that is changing, says Chris Edwards.
Increasingly, traditional boiler and radiator arrangements are giving way to new renewable technologies. Even with boilers, lower water temperatures are becoming the order of the day as efficiency is increased. This could lead some to suppose that the days of the radiator, which is firmly associated in most minds with high temperatures, might be numbered.

In reality the radiator is one of the best heat emitters to use with low temperature systems. Recent research, commissioned by Purmo from the Helsinki University of Technology, has demonstrated scientifically what we've known in theory for a long time; radiators are still highly efficient at lower temperatures. In Scandinavia, using them with lower temperature systems has been common practice for some three decades, but in the UK we've been slow to follow.

Lower running costs

Radiators can operate efficiently with a water temperature of 45 deg C and, in some systems, with water temperatures as low as 35 deg C. Being able to provide comfort heating at lower temperatures naturally means lower running costs, which will be a bonus to residential settings such as nursing homes, especially in the public sector where cost saving is imperative. With elderly, infirm or disabled residents, warmth is not just a matter of comfort, but is often vital to health, especially in colder weather.

More common use of lower water temperature systems with radiators will mean that residential care stays flexible while embracing greener technology. Radiators are easy to control as residents with one set of requirements leave and new residents, with differing needs, arrive.

The heating system can be controlled in zones, either to isolate an entire wing or allow communal areas to cool overnight; but the temperature in individual rooms can also be adjusted to suit each occupant simply by using a TRV. Many residents have limited mobility, which can mean that they spend days as well as nights in their own rooms; needing a warmer temperature during the day, and a cooler one at night to aid sleep.

With its rapid response times, the radiator allows the room to be cooled or warmed quickly to provide the ideal temperature at any time of day with ease. With a renewable heat source such as a heat pump, care staff being able to turn heat up or down at the radiator is a huge advantage, as it is best not to adjust the overall settings for the system once it has been installed and commissioned to run at its most efficient.

Panel radiators may once all have looked alike, but in recent years they have changed quite a lot, and not just in appearance. For a start, they have a much reduced water content, so they need less hot water circulating through the entire system. This in turn means less work for the heat source; be it a conventional boiler, which can now be turned down to consume less energy; or carbon-cutting renewable technology. They also have more advanced fin arrangements with a larger total surface area through which to emit heat.

We've learned to think differently about radiators in order to make them more adaptable to their surroundings. A narrow strip of wall, once considered too small to site a radiator, can now be the location of a vertical radiator. These can be as narrow as 300mm, but as tall as 2m, so they can provide a large surface area in a tight space - but you do need to ensure that you specify a product that has been expressly designed to work vertically.

We also now have triple panelled radiators which occupy the same amount of wall space as a single panel, but which provide far more output from one heat emitter. This type is, admittedly, deeper than a single panel, but not much more so than an older style double panel radiator. Crucially, these radiators allow you to site the heat emitter beneath the window, rather than place one single panel below the window and two others elsewhere.

When the radiator is located beneath the window, heat is deflected into the room, setting up a convection current which circulates warmth rapidly and evenly, plus it has the benefit of heating the room right up to the window, where residents often like to sit. Research also showed that when the radiator is installed here, less than one per cent of heat is lost through the outside wall over a year.

Delivering high efficiency

With other types of emitter, such as underfloor heating, the heat rises slowly, in layers (or strata) so that although the end user's feet may be warm, it could be some time before they are warm enough at shoulder and head height. Underfloor heating may be better suited to those with a more active lifestyle.

Whether you are selecting a heat emitter for a new build or a refurbishment project, you should still consider radiators as the first choice. In a refurbishment, replacing old radiators provides a good cost effective solution that will deliver higher efficiency with a new heating system. As a like for like replacement, they will also be quick and easy to install, especially as installers already have so much expertise and experience with them.

As long as you specify radiators made from high quality materials, and which carry a ten year guarantee, the system you install should be able to deliver at least 25 years of faithful energy saving service.

• The author is sales and marketing director for Purmo