Control processes

Dealing with condensate

When heat recovery is running up to 95%, the air is cooled considerably in the counterflow heat exchanger. The humidity in return air can then condense in the heat exchanger, and is collected in a condensate tray. A float registers a high level of condensate in the tray automatically.

To prevent stoppages, a drain can be fitted to the condensate tray to remove water from the unit. Alternatively, the air handling unit
can be fitted with a fully automatic condensate pump.

Built-in float sensor detects
unwanted
build-up of condensate.

Operation of Airmaster ventilation untis in cold climate

Airmaster’s decentralised ventilation units are also designed to function optimally in cold regions such as in northern Scandinavia and Greenland, where a large number of units are already in operation.

The ventilation units have built-in intelligent control processes which automatically regulate components and can adjust the operation of the unit, if necessary, to frost-proof the unit, or to maintain the desired supply temperature during periods of low outdoor temperatures.

Frost protection

The high efficiency of the heat exchangers ensures low energy consumption for heating the supply air, which is both environmentally and economically beneficial. However, this high efficiency may cause the exhaust air to condense in the heat exchanger during cold periods. If the outside air is cold enough, there is a risk of the condensation freezing and thereby blocking the exhaust air in the heat exchanger.

It goes without saying that this problem has been addressed in Airmaster’s ventilation units. The Airlinq® control efficiently prevents the formation of ice by gradually reducing the volume of the supply air and possibly increasing the volume of the exhaust air to the level required. As a result, the exhaust temperature rises again. If this process is not enough to prevent the formation of ice in the heat exchanger, the Airlinq® control will protect the unit by shutting it down and activating an alarm signal.

Controlled supply temperature

For optimal heat recovery, Airmaster’s ventilation units are fitted with high efficiency countercurrent heat exchangers. This helps ensure that the units are able to provide a comfortable supply temperature with a balanced airflow for much of the year, without the use of a heating element.

The Airlinq® controller continuously monitors the temperature in the ventilation unit and automatically adjusts the airflow if the desired supply temperature cannot be maintained within acceptable limits during certain periods. In this case, the control will gradually reduce the volume of the supply air and possibly increase the volume of the exhaust air to the level required.

Heating element

Airmaster ventilation units can be supplied with either an electric heating element or a water heating element.

The heating element is automatically activated when the supply temperature drops below the desired level. (See Figure 1).

Elektrisk eftervarmeflade

Electric comfort heater

If the ventilation unit is fitted with a heating element, the control will only cause an imbalance in the airflow to the extent necessary once the capacity of the heating element is utilised 100%.

Ventilation units with an electric heating element come with adaptive control of the heating element, where the output is continuously adapted to the current needs. This ensures energy efficient operation as well as a stable supply temperature.

 

 

Figure 1: Simplified principle sketch of ventilation unit with heat exchanger and heating element.

Figure 2: Simplified principle sketch of ventilation unit with heat exchanger and
pre-heating element.

Pre-heating

Airmaster ventilation units can be fitted with an electric pre-heating element or a “virtual pre-heating element”.

If the ventilation unit is fitted with an electric pre-heating element, it heats the outdoor air before it reaches the heat exchanger, thereby preventing the formation of ice.

The location of the pre-heating element is illustrated in Figure 2.

elektrisk forvarmeflade

Electric pre-heating surface

 

 

Figure 3: Simplified principle sketch of ventilation unit with heat exchanger and heating element for virtual pre-heating function (VPH).

Virtual pre-heating

Alternatively, on some units, frost protection can be provided by means of a heating element and the “virtual pre-heating” (VPH) function.

During periods when there is a risk of ice forming, a small volume of supply air can be made to bypass the heat exchanger via the bypass damper (see Figure 3). This prevents the exhaust air from cooling as much in the heat exchanger, thereby preventing the formation of ice. The supply air which bypasses the heat exchanger is remixed with the supply air which has passed through the heat exchanger before the heating element heats the air to the desired supply temperature.

If the ventilation unit is fitted with a pre-heating element, or a heating element combined with the “virtual pre-heating” function, the control will only cause an imbalance in the airflow to the extent necessary once the capacity of the heating element is utilised 100%.

Water heating surface

Most air handling units can have a water heating surface fitted as an alternative to an electric comfort heating surface. A water heating surface also ensures the required inlet temperature. The large surface area of the heating surface ensures efficient transfer of heat energy to the inlet air.

The Airlinq control system starts and stops the heating surface using a motor-driven valve. The heating surface is supplied built-in to the air handling unit, or as part of the duct system. Connection to the local heating system is therefore quick and simple.

Frost protection of water heating surface

The water heating surface is fitted with a separate, self-controlling heat retention valve, which ensures a minimum temperature even when the air handling unit is switched off. All nominal values for the water heating surface are preprogrammed into the Airlinq control system. The heating surface is therefore protected against frost and is directly functional.

Water heating surface

Ventilation unit with the option of separate pre-heating and heating elements.

  • AM 500
  • AM 800
  • AM 900
  • AM 1000
  • AM 1200

Ventilation unit with the option of heating element with virtual pre-heating function.

  • AM 150
  • AMC 150
  • AM 300
  • DV 1000

Flow control 

Most air handling units can control the airflow using flow control. Flow control means that the airflow is stated in m3/h and ensures balanced operation, at varying pressure difference on the supply and extract air. To convert airflow to m3/h, a measuring nozzle is fitted inside the air handling unit between the fan and the main box, which measures the differential pressure.

The differential pressure is measured for the supply air and extract air respectively, and then converted to an airflow in m3/h.

Automatic bypass

The Airlinq control system can open the bypass gradually if the inlet temperature exceeds the required level. Cooler fresh air will be allowed to bypass the countercurrent heat exchanger, ensuring that the inlet temperature set is maintained. Airlinq will adjust the inlet air temperature to achieve a higher cooling output. If the room temperature exceeds the level set, e.g. as a result of strong sunshine, the bypass will open automatically.

If a cooling module is fitted to the air handling unit, Airlinq will activate it automatically if cooling using fresh air is insufficient. When the cooling module is working, the bypass is still used to regulate the inlet air temperature.

Night time cooling

If the room temperature exceeds the maximum level set during the day, all Airmaster air handling units can automatically cool down the room using colder night air. It will be registered by the Airlinq control system, and started automatically. If necessary, the function will use the bypass damper and cooling module to achieve the cooling output required. The building and its contents will be cooled, and a reduction of the room temperature will be achieved for the next day.

Cooling using cooling modules

Control processes for cooling

Energy meter

All Airmaster air handling units can be fitted with an energy meter, to provide a precise overview of the unit’s electricity consumption. The figures can be read directly on the meter’s display. Power consumption can also be monitored using the Airlinq Service Tool program or via Airlinq Online, if the air handling unit is connected to this.

Ready for a breath of fresh air

At Airmaster, we are “decentral” through and through. We are unrivalled when it comes to creating the best indoor climate and optimal well-being because we take each room and its occupants into account – and because we constantly strive to improve on what we do.

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