Performing heat treatment while protecting material

If thermal pest control is carried out correctly, the temperatures do not rise high enough to affect the fabric of the building or its furnishings. Nonetheless, critical objects should be removed before heat treatment starts. These include:

• Sensitive electronic devices such as printers or medical equipment
• Food and medication
• Cosmetics and washing products
• Aerosol cans (e.g. hairspray or deodorant) and containers with carbonated contents
• Fire extinguishers
• Pictures, antiques, jewellery, records, CDs etc.
• Plants
• Music instruments
• Various fire loads like paper

Electrical appliances that remain in the room during heat treatment must be free of voltage. Refrigerators and freezers, in particular, must be switched of; otherwise, the compressor reacts to the rising ambient temperature with an increase in output, and may be damaged. Sprinkler systems must be protected with cover flaps, and smoke or fire detectors must be put out of operation. Dust should also be completely removed before starting thermal pest control. In addition, depending on the operating location, it must be determined whether the heat treatment unit requires ATEX-approval.

Preparing places pests may retreat to before treatment

At the beginning of heat treatment, the warm air makes the pests more active, and they move towards the heat source. However, as soon as the air temperature exceeds the animals' comfort zone, they flee to cooler hiding places. For this reason, possible escape areas such as wall breakthroughs, empty pipes, or cables should be taped or covered with diatomaceous earth (mountain flour), which dries out the pests, before the room is treated. Door-frames are used by pests to escape outside and should also be taped.

Thermal pest control does not require temperatures that exceed 60°C. Therefore it does not damage buildings, machinery or equipment. In order to protect the fabric of the building during the heat treatment, the heat treatment furnace should slowly heat up the circulating air, and cool it down again slowly after the treatment phase. The temperature change should not be more than 6°C per hour to avoid tension damage to the fabric of the building. Thermostats ensure that the temperature remains at a constant 50 - 60°C, so that pests are killed, but no heat damage is caused to property.

To ensure that all pests are exposed to the heat, the temperature must be maintained for at least one hour even in the most inaccessible parts of the room being treated. Temperature sensors at the points with the most unfavourable thermal conditions allow temperature values to be recorded and documented, and guarantee complete treatment of the room. As the heat penetrates all materials over time, pest populations can be killed off even in places that are difficult to access. Areas that are hardly reached by natural air distribution can be treated separately.

Flexible and energy-saving treatment thanks to more efficient furnaces

The duration of thermal pest control depends on the location to be treated and the intensity of the pest infestation. A hotel room, for example, can be thermally disinfected in about 48 hours. Depending on the area and the thermal insulation properties of the building material, several heat treatment furnaces may need to be used. Modular heat treatment units offer operators the advantage that they can be set up and dismantled quickly, and adapted flexibly to structural conditions.

Each cubic metre of room volume requires about 2-4 kWh of electricity for treatment. The energy efficiency of the heat treatment depends on aspects of the room itself: for example, how difficult it is to heat the concrete, how well the room is insulated, and how high the heat loss is. The distribution of warm air in the room also influences power consumption significantly. Heating using the air recirculation method ensures that only the air in the room is heated and saves energy. Special fans can also be used to conduct the warm air that has risen upwards back to ground level. This means that fewer heat treatment furnaces are required, which reduces costs.