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Business: +49 2452 962 400
Industry: +49 2452 962 777
End-consumers: +49 2452 962 450
Monday - Friday: 8:00 a.m. - 5:00 p.m.

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Business: +49 2452 962 400
Industry: +49 2452 962 777
End-consumers: +49 2452 962 450


Mobile heating units from TKL find their application in a variety of fields and sectors from construction over industry and agriculture to the service sector. One has to distinguish between three kinds of heating units:

1. Electric heaters, direct and indirect heaters

Direct and indirect heaters can be fuelled with either heating oil or gas.

1.1 Direct heaters

In a direct heating system, the fan which blows out the heated air also provides for the combustion air. The fuel is dispersed in the combustion chamber, ignited and combusted. Then the hot gases are exactly dosed and mixed with the venilator's main air stream. This process is termed 100% performance, because the entire developed heat can be set free in the rooms that require heating free of loss. This is also the reason why direct heaters do not require a chimney.

The disadvantage of direct heaters is that the exhaust fumes and the moisture created by this combustion process are emitted directly into the room. It is therefore necessary to provide for adequate ventilation in order to conduct them away.

Warning: During combustion approx. 1.64 kg of water vapour are produced per litre of fuel; this in turn condenses on walls and ceilings.

Conclusion: The development of moisture makes direct heaters totally unsuitable for drying processes and construction drying.

1.2 Indirect heaters

It is only possible to obtain clean, dry air without polluting the ambient air with water vapour or the by-products resulting from the combustion process by using indirect heaters. In such heaters, the air to be heated is completely separated from the combustion chamber.

The fan that blows the warm air into the rooms that require heating also provides for sufficient combustion air, but the combustion by-products are conducted out into the open. The air is conducted past the heat exchanger, the enlarged surface of the combustion chamber, where it is heated before being discharged into the room. Indirect heaters with chimney are ideal for rooms in which only limited ventilation is possible or where inflammable products which would otherwise create a fire hazard are stored.

1.3 Electric heaters

Electric heaters are the safest, fastest and easiest way to trouble-free heating. All you need is a power supply - no further effort is necessary.

Electric heaters are often used for building projects, pavilions, warehouses and workshops, on ships, in distribution centres, cowsheds, garages and in provisional accommodation.

But above all they are used as a supportive measure when dehumidifiers are employed in construction drying, because - the higher the room temperature, the shorter the drying time.

2. Indoor or outdoor installation

Heating units with a performance exceeding 100 kW are often installed outdoors because of their sheer size. In such cases, the heated air is transported into the inside rooms via air hoses.

The disadvantage regarding a heating unit that is installed outdoors is that as a result it consumes significantly more fuel than a heating unit which is installled indoors.

Heating units that are installed indoors function on the basis of recirculation: they heat the already heated ambient air. A heating unit that is positioned outside heats the cold outdoor air and discharges it into the rooms inside. It is therefore logical that a heating unit that is positioned outoors requires much longer to heat up a room to the desired temperature than a heating unit that is positioned indoors.

This is one reason why the fuel consumption of outdoor heating units is often 2-3 times higher than that of their indoor counterparts. And this is why TKL offers you heating units which as a rule are only 80 cm across so that they can fit through most doorways.

Calculating heating performance:

You will find an approximate calculation for the required heating performance under the menu item „capacity calculation”. For an exact calculation of the heating requirement - especially for large-size rooms - please contact our team of experts.

Our goods and services in the heating and heating units to hire sector:

On request we can also analyse your individual requirement situation on location, and determine the number and type of machines and appliances which you need before presenting you with a custom-made project solution. We can provide adequate numbers of suitable heaters to match almost every conceivable requirement.

In addition to our on-site inspection service, our machine installation and deinstallation, maintenance and monitoring service, we can also offer you most of our heaters to hire without the provision of these service packages.

For self-collectors or brought to you directly to the building site by our bring and collect service, according to your wishes. Heaters at top conditions.

Please ask for our attractive season rates: heating to hire for a whole season at a fixed price.

Buying or hiring, new or used products, financing or leasing

Just about all the odour neutralisers in the TKL hiring program can be 'bought' or leased directly from our system partner, the industry supplier Trotec, should you be planning on using them over a longer period.

Whether you choose to hire or buy, we have just the right contact person to match your requirements.

You can regularly find attractive used air conditioning units at unbeatable prices in our online marketplace at

TKL and Trotec offer you service from a single source - also in case of financing and leasing! For further information, please contact us online at or phone us on: +49 2452 962 400.