INFRARED HEATING

What is infrared heating?

The ultimate source of radiated heat is the sun, which generates vast amounts of infrared heat through gas consumption. This infrared heat passes directly through space, but it warms the surface of the earth and is, in fact, the energy source that makes life possible on earth. On a sunny day in winter the sun’s warmth comforts us even though the air around us is below comfort temperature.

Gas fired infrared heaters are sometimes called mini suns because they both rely on gas consumption (either propane or natural gas) to generate heat. Infrared heat warms people and objects at occupancy level, not the air in the room. This is a major advantage because warmed air rises to the ceiling where it is not needed, and wastes the money spent to heat it.

How are conduction and convection heating different than infrared heating?

Heat can be transferred in one of three ways:

• By conduction through solid bodies, such as through a windowpane in your heated house to the (cold) outside. The rate of heat transfer by conduction is proportional to the temperature difference and the conductivity of the material through which the heat travels.
• Through convection by warming air and moving the warmed air to a cooler area. For example, air is warmed as it passes over the elements of an electric heater; the warmed air rises by convection and draws cooler air behind it to in turn be heated by the heater.
• Through radiant heat transfer, which unlike the other two methods requires no intermediate conductor material or convector medium (air). That’s because infrared energy, like light, passes directly from the source to the receiver. The rate of heat transfer depends on the emissivity of the source, the absorptivity of the receiver, the difference between their absolute temperatures (raised to the fourth power), and the distance between them.

How do infrared heaters work?

Most infrared heaters employ gas combustion (propane or natural gas) to heat a steel tube (tube heater) or ceramic surface (luminous heater), which subsequently emits infrared heat. It’s important to note how much infrared heat is emitted. You should also be aware that an infrared heater produces both infrared radiant heat (that is directed at people and objects) and convection heat that rises and is for the most part lost.

Even Schwank’s economy models produce more infrared heat than competing systems, and our top-of-the-line heater, the supraSchwank, delivers the most infrared heat (81%) of any heater in the world - by far.

Which technology is newest – tube or luminous (high intensity) heaters?

Tube heaters were introduced after luminous heaters, but the best luminous heaters utilise relatively new technology, and employ more advances and offer significantly better efficiency - a key advantage of Schwank luminous heaters. It’s also important to note that the best choice depends on the budget, the application and the payback period (when fuel savings have paid for the heating system).

Is infrared heating safe?

While the sun is a terrific source of infrared heat, it also delivers damaging UV rays, which leads some people to falsely conclude that the same problem applies to infrared heaters. The sun produces UV because it is an extremely high temperature source; Schwank infrared heaters are a medium temperature energy source – the ideal range for three reasons: it is below the UV range, a greater portion of the heat energy is converted into infrared heat, most materials are highly receptive to medium wave infrared heat. The latter is a key reason why Schwank infrared heaters can heat, dry and cure faster and more economically than competing systems.

How is infrared heating used to warm spaces in a building?

Gas-fired infrared heaters are mounted overhead to direct infrared energy to the floor and the objects, including people, at the occupancy level of the building. The infrared energy is absorbed by the floor and objects at floor level - all of which become warm and in turn heat the air in the building. Moreover, the floor and objects continue to release heat to the air, even after cold air is introduced or the infrared heaters are turned off. Convection heating, in sharp contrast, has two major drawbacks: the total loss of heated air to ventilation air changes; hot air ‘stratification’ as it rises to the ceiling, where it is not effective in providing comfort to occupants.

How is the temperature controlled in an infrared heating system?

A thermostat shuts off the infrared heaters when the desired air temperature is reached. Better results are achieved with a black bulb sensor that measures both the air and the mean radiant temperature to provide true comfort temperature. This special feature, and many others, is offered by the Schwank ThermoControl Plus.

What are low density and high density heaters?

This is a common source of confusion, resulting from the similarity between the word density and intensity. The proper wording is low intensity (tube heaters that have a relatively ‘low’ emitting surface temperature) and high intensity (luminous heaters that have a relatively ‘higher’ emitting surface temperature).

SCHWANK INFRARED HEATING SYSTEMS

Does Schwank offer a complete range of infrared heaters?

Yes. Schwank’s unmatched selection of high efficiency infrared heaters includes tube heaters, luminous (high intensity) heaters, and Outdoor.

What is the difference between a Schwank infrared tube heater and a Schwank luminous (high intensity) heater?

Both types are energy efficient, but they employ different techniques to convert fuel into radiant heat.

In a Schwank tube heater, the radiant heat is produced by a calorised steel tube that is heated to temperatures ranging from 200-600 degree Centigrade; in a Schwank luminous heater, the radiant heat is produced by a ceramic surface (comprised of varying numbers of ceramic tiles) at 900 degree Centigrade. Note that infrared heaters are also often called ‘radiant’ heaters.

Are Schwank heaters competitively priced?

Yes. You also have the added advantage of choosing the model range and performance level that suits your budget. Moreover, the unmatched efficiency of Schwank heaters means you get quick payback. Remember, the full life-cycle cost of a heating system includes the purchase price, the fuel cost, and maintenance costs. In fact, the first-year fuel cost usually represents more than 30% of the total cost.

What is the fuel source?

Schwank infrared heaters are gas-fired and can be fuelled with either propane or natural gas.

How do I choose between a tube heater and a luminous heater?

The key factors are the mounting height of the heater and the heating application. If the mounting height is between 5 and 20m, or you need spot (or focused) heating, a luminous heater may be best. A tube heater is best if:

• the mounting height is between 4 and 7m
• you require a sealed combustion system (direct venting and combustion air introduced directly to burner)
• the objective is to spread heat over an area of low heat loss

Which heater produces the best comfort level?

There is plenty of misinformation on this issue. Here are the facts: if a tube heating system and luminous heating system are installed properly, there is no difference in the comfort levels. A common mistake is to install tube heaters when the ceiling height is better suited to luminous heaters. High efficiency luminous heaters such as primoSchwank and supraSchwank will provide better economy of operation than tube heaters – money in your pocket month after month, year after year.

Can you buy a setback thermostat that measures both ambient and infrared heat?

Yes, Schwank offers the ThermoControlPlus. It delivers maximum fuel savings and comfort because it measures both ambient and infrared heat. Competing thermostats give up a large percentage of possible fuel savings by only measuring the room air temperature.

ENERGY EFICENCY

Which heater is most energy efficient?

Don’t be misled by unsubstantiated claims of efficiency. Efficiency rates should be backed by test reports from independent certified labs, the approach taken by Schwank.

With the same gas input, the supraSchwank luminous heater (the world’s top efficiency model) produces more than twice as much radiant heat as a standard luminous or tube heater. Energy efficiency is vital when comparing systems, because the life-cycle cost of a heating system includes not only the cost of purchase, but also the cost of the fuel to operate it. On that basis, the best buy is always a Schwank heater.

Why are Schwank infrared heaters more efficient than competing models?

Schwank infrared heaters meet and exceed the strict European standards for efficiency and hence give you far more heat for your money. Our mission is to deliver the best in commercial and industrial heating solutions at the lowest life-cycle cost.

Many manufacturers have attempted to capture market share by designing and building inexpensive, low efficiency infra-heaters that meet the minimum requirements. These heaters may appear to have an attractive purchase price, but they are far more costly in the long run because they use more fuel and deliver less infrared heat (up to 60% of the heat is convection heat that rises to the ceiling and is wasted). And besides the poor economic performance, these cheap infrared heaters produce marginal comfort levels that reduce productivity.

Why are Schwank luminous heaters so energy efficient?

As well as utilising modern materials and technologies in construction of the heater, Schwank ensures that your infrared heating system is properly designed. Properly sized and placed heaters, will reduce fuel consumption by 30 to 60%, compared to a conventional heating system.

A bad design utilising a smaller number of large capacity units, mounted at maximum heights, produces inadequate comfort and higher operating costs that far exceed any savings on the purchase\installation price.

Have any studies been done to confirm the efficiency of Schwank infrared heaters?

Yes, engineering studies supported by ASHRAE have determined that using standard infrared heaters the total Kw input of a heating system can be reduced by up to 15% compared to calculated design heat losses. Tests performed by a certified independent laboratory confirm primoSchwank and supraSchwank radiant efficiencies in the 65 to 82% range. This means the total Kw input with Schwank heaters can be reduced from 27% to 41%, depending on the Schwank infrared heater employed.

Are infrared heaters with equal gas inputs interchangeable?

No. There could be significant differences in the infrared output, based on the burner material, configuration, operating temperature, mounting angles, combustion air input and reflector design. For example, on average, more than 50% of the heat generated by infrared heaters is convection heat, and in some inferior models the percentage of convection heat is as high as 65%.

There may also be considerable differences in terms of installation specifications, including mounting height, angle of mounting, distance between heaters, and distance between exterior walls or between rows of heaters.

What are the features of a top performing infrared heater?

In both tube and luminous infrared heaters, the reflector should completely cover the emitting surface of the heater. Ideally, the reflector should protrude beyond the surface of the heater. Full coverage is a must to trap convection heat and increase the infrared output.

In tube heaters, ask about the flame length. In standard tube heaters, the flame length is a metre. In Schwank tube heaters, the flame length is up to 5m. A heater with a long flame will increase heat farther down the tube, resulting in more uniform heat distribution. You should also ensure the ends of tube heaters have a solid cover. That is important to ensure complete coverage of the tube and entrapment of convection heat. Insulation of the reflector also increases radiant efficiency

Luminous heaters should also have a reflector that completely covers the emitting surface of the heater. On a multi-burner luminous heater, each burner panel should have an independent flame sensor to ensure gas shutdown when there is a burner malfunction. Insulation of the reflector is important in increasing the radiant efficiency.

INSTALLATION & DESIGN

What is the difference between space heating and spot heating?

Space heating refers to the warming of an entire room or building for comfort or to avoid freezing. Spot heating refers to the warming of an area within a much larger unheated structure, such as the spectator stands in a sports arena, a work station in an unheated warehouse, work stations in a courier depot, or a restaurant patio.

Technical background

Spot or area heating is a method of providing comfort to an individual or group of individuals without heating the entire space or building to a comfortable air temperature level. Schwank luminous infrared heaters are the only heaters which offer a practical, economical solution to the problem of providing comfort in relatively large unheated structures that are sparsely populated. No other method of heat transfer can warm individuals without wasting heat to surrounding air.

The design criterion for the application of Schwank infrared for spot heating is different than that of space heating. In a space heating application, a combination of direct radiation and air temperature creates the needed comfort condition. In spot heating, only the direct radiation comes in to play in determining the comfort attained by the individuals in the heated area.

To successfully design a spot or area heating system, the designer must become familiar with the design conditions in the area to be heated. The air velocity in the area must be determined accurately. The surrounding air temperature and the activity level of the individuals in the area to be heated must also be determined.
Once the design conditions are established, the proper size and model of the Schwank luminous heater can be selected to effectively heat the individuals or area in question.

What are the essential elements of a good installation?

Proper spacing down the length and width of the building is essential to ensure consistent comfort levels. The design should also take into account safety margins for zone heating, warm up times and comfort levels. In many buildings, the best heating solution employs a mix of tube and luminous heaters.

How do you handle contaminated air conditions?

Direct ducting can be used to supply clean outside combustion air to a tube heater. With a fresh air duct attached and direct venting to the outside, a tube heater is a sealed combustion system that can handle very dusty conditions. In selected applications with ‘low level’ dust contamination, luminous heaters can be utilised, provided that regular maintenance and cleaning are scheduled.

The properties of chemical contaminants must be fully understood prior to considering any heating system, but often a ‘sealed combustion’ tube heating system can be the viable solution.

SERVICE

Where can I get spec sheets and engineering data?

Product information is available on this web site. You may also Contact Us at our office in Sutton.

How quickly can I expect product delivery?

Most stock is available at our warehouse and can be shipped immediately. We strive to make your time frame our time frame. For factory to jobsite orders, standard shipment time is a few weeks.

Aside from my local Schwank manager, who can I call for technical assistance?

Call Schwank's office in Sutton. Contact Us