Values and standards
The new BS EN 16430 Testing Standard
Lingen (Ems), January 2016 - The BS EN 16430 came into effect in 2015. Finally, trench heating of different manufacturers are comparable with each other.
BS and other standards provide design confidence for multitude technical systems to both, consultants and architects. But what if there is no suitable standard for a product? This applied to trench heating and cooling until March 2015. Accordingly, performance data circulating for those units were confusing and less reliable. The new BS EN 16430 now puts an end to this. Kampmann Katherm units have already been tested according to the new standard. And even more...
Trench heaters such as the Kampmann Katherm unit have been used for heating spaces with full-height glazing for decades. The basic version uses the principle of natural convection: The warmed-up air rises upwards at the cold glazing and provides cold air screening. From the ceiling it slowly penetrates the space and provides heat throughout the whole body of the room. This process can be accelerated by using of fan-assisted units. Todays EC-fan technology allows fan assisted trench heating to be installed in areas with highest requirements with regards to noise and electrical power consumption. Since Kampmann has established the Katherm HK in the market, trench units are increasingly used for cooling. However, cold air by its nature does not rise up - it has to be forced out, using fans. This is the challenge as, if cooled air falls to the floor too quickly, it's partially drawn in again by the fan (so called: short circuit). There is a risk, that trench cooling units can blow out cold air, however, they are unable to effectively cool the room, as the cold air is circulating in short circuit (see picture 1).
It could now be assumed that the measuring data of certain manufacturers would disclose the deficient cooling capacity. However, up to now there hasn't been a uniform European standard for measuring the performance data, especially not for trench cooling units. Consultants, builders, and architects were left in doubt as to the actual performance of the quoted products - it was not possible to compare the individual units like for like. Accordingly, the introduction of the new standard for "Fan-assisted radiators, convectors and trench convectors" was overdue. Since June 2015 the standard has now been valid and has put an end to the mess with various measuring methods.
It's been a long way: Nearly seven years passed from the instruction by the European Committee for Standardisation (CEN) in 2008, over the first draft, to the national and European objection meetings and approval by all CEN-countries. The standard has been based on the BS EN 442 which defines the performance measuring of radiators and convectors but doesn't make any comments on trench heaters and cooling at all. Yet the BS EN 442 was used for testing of trench heaters, supplemented by the German DIN 4704-4 which applies to trench heaters, however, again not to cooling mode. Finally, there is the EN 14518 which measures cooling capacities, however, that of chilled beams. Some manufacturers avoided the standards and used the entering air temperature into the coil to calculate the cooling capacity - an inappropriate, distorting method as the reference air temperature which is relevant for the selection and the entering air temperature in most cases strongly deviate. The least reliable are completely calculated performance data without any measurement at all. And yet complete manufacturers' catalogues are full of these abstract data.
A case for the sound
The BS EN 16430 is practice-oriented. In the test booth the trench is installed at a distance of 50 mm from the conditionable rear wall, simulating the facade. In cooling mode the surface temperatures of the test booth, particularly at the rear wall are adjustable to 28 °C +/- 0,5 K. The reference air temperature is measured at a distance of 2 m from the façade at a height of 0.75 m. A set-up which reveals whether or not a convector is able to cool efficiently, as the position of the reference air temperature sensor represents the location in the room, where persons are located, i.e. sitting in front of their desk. At the end of the day, the units shall provide a comfortable climate in the zones, occupied by persons. Please do not mix up the reference air temperature, measured 2 metres away from the facade, 0,75m above finishes floor level with the entering air temperature into the unit/coil, as you may know from FCU applications. There could be a significant difference between these two temperatures, when cooling from low level using trench cooling. Selecting a trench cooling unit based on an entering air temperature of 24°C could therefore result in a reference air temperature of 27°C or even more. This is due to the fact, that the above mentioned short circuit could be minimized by manufacturers knowledge and experience, but not be avoided completely. If you make sure, that the manufacturer you selected has tested their units to the new BS EN 16430 you will be on the secure side and the room temperature will be, as requested by yourself.
Apart from the correct measuring according to BS EN 16430 the sound performance is a decisive issue for the evaluation of a trench heater. The dimensioning of convectors should always be based on the sound pressure level. Only then it can be guaranteed that the required thermal output or cooling capacity is reached in compliance with the sound limits. If the convector is not measured according to the new standard it may happen that in practice the unit will have to run at considerably higher speed in order to reach the thermal outputs or cooling capacities and will produce inacceptable sound emissions. With the BS EN 16430 these uncertainties are obsolete, as the new standard also demands, the noise power data of the units to be measured . The standard measures convectors reliably and provides planning security. For the sake of transparency it is decisive that all manufacturers measure according to BS EN 16430 from now on.
Considerably compliant: The Katherm HK
Laws, standards and guidelines, even if a burden to manufacturers and consultants, are essential. Only units which are legally compliant and have been measured to a standard fulfil the expected performances, provide a good and healthy room climate and give design confidence. A trench heater which already complies to all above requirements is the Katherm HK, a real Kampmann classic and bestseller as well as the market leader when it comes to trench cooling.
The Katherm HK has established trench heating with cooling function in the market. Before the Katherm HK was introduced in 1998, cooling from floor level was considered technically difficult. Kampmann proved cooling from the floor to be indeed achievable - and has been able to keep this lead in knowledge until today. The last revision of the Katherm HK (see picture 2) underlines the leading position of the unit: The dimensions, particularly the height, could again be considerably reduced to just 130mm. The Katherm convector has already been measured to BS EN 16430, in parallel the comfort has been optimised according to BS EN ISO 7730. The thermal outputs, cooling capacities as also noise emissions have been optimized and the so-called short circuit nearly eliminated. The units are suitable for dry and also wet coil cooling, with inbuild condensate pumps available upon request. To comply with highest hygienic requirements, the condensate tray is now completely accessable for cleaning.
To confirm that a manufacturers product has been tested according to the new BS EN 16430, please have a look into their CE Declaration of conformity. The new standard should be mentioned there.