Why is warm air heating consistently popular for large spaces?
Of the various options that are available for heating spaces such as factories, warehouses and retail ‘sheds’, warm air heating has been the most popular for decades. So why is this? The reason is that not only does warm air heating offer a number of significant benefits for the majority of these buildings, it has also proven those benefits time and again, in many different applications. Consequently, it’s worth considering just what those benefits are.
Standard indirect-fired non-condensing warm air heaters are able to deliver minimum net efficiencies of 91% and the latest condensing models provide even higher efficiencies with a minimum 101% (net) at both full and part load, in compliance with the latest EU regulations. A further significant benefit is that the heat input can be closely tailored to meet the building’s heating requirements. Configured with optional high/low or modulating heat outputs, the heater(s) automatically reduce output once the building environment conditions have been attained, offering a comfortable environment without significant swings in temperature.
With warm air heating, system output can usually be matched to the building load requirements. The same is not always true of alternatives such as radiant where heat input is sometimes compromised to provide adequate coverage of the heated zone. This is typical for modern well insulated buildings. Depending on the application, warm air heating systems may be combined with de-stratification fans for even greater efficiency. The Carbon Trust estimates that the use of de-stratification fans in industrial buildings with high ceilings that are operating a warm air heating system can reduce energy consumption by 20%.
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Warm air space heating systems use a fan to draw air in from the space being heated, pass it across a heat exchanger, and distribute the warmed air evenly throughout the space. This even distribution by warm air heating systems is in contrast to heating technologies such as radiant heating that only warms objects that are in ‘direct line of sight’. This means they are vulnerable to ‘shading’ issues that leads to uneven heat distribution.
Warm air heaters offer considerable flexibility in terms of their location, ensuring the layout of the heating system is optimised for the configuration of the space being heated. They can be suspended above the space, mounted on walls or they can stand on the floor. Models are available with discharge heads or louvres for direct warming of the air; alternatively heaters can be specified for connection to ductwork for distribution across a wider area.
For areas with dense racking a special warm air heating technology, developed by Powrmatic and known as ‘ air rotation heating’ can be used. These systems use high powered fans to move large volumes of air at low velocities throughout the space and are unaffected by the layout of that space. A feature of warm air heaters is that they also offer flexibility in terms of air movement. Most systems re-circulate warm air within the building; however they can also be used to provide air movement in the summer by operating ‘fan only’. In addition heaters can be equipped with fresh air intakes – particularly useful for dusty environments or where fresh air is considered beneficial.
If a building has a process with extract ventilation then it is often a good idea to bring the replacement air in via a fresh air input to the heater. In that way, the input air is warmed and tempered preventing cold uncomfortable draughts.
Warm air heating offers a choice of heat sources to best suit the application and current energy costs. Warm air heaters are typically operated on natural gas, LPG or light fuel oil.
Warm air heaters are also highly controllable, enabling their operation to be closely aligned to the requirements within the space – thus avoiding wasted energy. For example, if there are some areas of the space that are only used occasionally it may be beneficial to zone the heating system so that these spaces are not heated to the same temperature as areas where people are working all day.
There will also be benefits to optimum start and stop control to minimise energy consumption. There is more information in our Guide to Controlling Your Heating System.
This article outlines the key benefits of warm air heating in general terms, but it is important to note that there is no ‘off-the-shelf’ solution that will suit every application. However, the inherent flexibility of warm air heating enables each system to be precisely tailored to the project in hand.
There are also benefits to partnering with specialists in the field and taking advantage of their knowledge and experience to ensure that the most appropriate solution is provided.
Premier heating Services (EM) Ltd offer a ‘without obligation’ site survey, heating load assessment and system design service – along with ongoing support through to commissioning and beyond.