The newest breed of gas-fired air heaters is designed for large open spaces such as factories, warehouses, sports halls, conference centres, exhibition halls, arenas and swimming pools. Features include fully-modulating burners which boast accurate temperature control and high efficiency, minimal or no ductwork requirement, pressurisation of space to ensure a clean atmosphere, ventilation/cooling during summer months and flexible installation options. In order to achieve the best solution for any large open space environment, careful consideration must be given to a variety of factors. After all, two spaces of identical size and shape can present very different characteristics and requirements.
Compare, for instance, an industrial warehouse where the majority of the activity involves semi-automatic fork-lifts, with an exhibition space. Factors such as occupancy and lighting levels, as well as the size and usage of the entranceways could not be more different. The specifier needs to calculate the heat load for the building accurately as well as model the circulation in what is likely to be a very tall space. Furthermore, the requirements for ventilation, and the replacement of that air, must also be considered.
Many modern factories and warehouses feature composite steel cladding panels where the insulated core cuts heat loss through the envelope to a good degree, yet warmth will still be lost through ventilation. Where extraction is part of the production process – if dust is generated or fume cupboards have to be employed – this effect will be greatly pronounced. A supply of heated replacement air is therefore required to maintain comfort levels. If it is not, the extraction system will perform inefficiently and a negative pressure may be created. This could lead to cold air being drawn in through leakage around the envelope.
For new installations, the supply of heated make up air can often provide adequate ventilation, without the need to install additional extract units. However, where additional extraction is deemed necessary, this can be integrated into the same unit to facilitate both input and exhaust flows; with the option of mechanical heat recovery from the exhaust side. The latest gas-fired air heaters can meet these combined demands economically, featuring efficiencies of 100% (based on NCV) thanks to fully modulating burners and effective intelligent controls.
The fully CE-approved, Stokvis Econo-Air range of gas fired air heaters encompasses both direct fired (SDF) and indirect fired (SIDF) models which are able to achieve these multiple objectives. A turn-down ratio of 20:1 guarantees flexible response, while output rises from 15-900 Kw for the indirect units, and 30-1200 Kw with the direct firing options. There is also a comprehensive selection of accessories available, enabling the installation to be customised to the different requirements of the building concerned.
When heating large open areas, it is ideal to have a wide range of air distribution heads available in order to facilitate ductless distribution. This is achieved by slightly pressurising the internal space to ensure even distribution both vertically and horizontally. This avoids the need for extensive duct runs or de-stratification fans. Where the building geometry does, however, demand ductwork, then Econo-Air units can be supplied with backward or forward curved fans to overcome resistance within the runs of up to 2000 Pascals.
For further information on Stokvis gas-fired air heaters call 020 8783 3050, or visit www.stokvisboilers.com.