Water condensation in fans and equipment

In some cases during the improper installation of fans, it may happen that condensed water runs into the fans or accumulates in the fan. This condition, of course, can endanger the function of the fan or can lead directly to its destruction.

During the installation of fans in bathrooms, it is necessary to avoid mounting fans in forbidden zones contrary to their protection such as in showers and within reach of the bathtub; adhere to the distances according to the standard. We also try to mount fans in a manner so that condensate cannot run through them, which occurs when very hot air with high humidity is cooled. Our experience is that the volume of the condensate may amount to litres, depending on the working conditions (example: the fan ventilates 100 m3/hour; 1 m3 air contains 45 g water, from which approximately 4.5 litres water per hour are condensed, if air is cooled in the pipe below the temperature of the dew point). It is suitable to install small axial-flow fans with the axis in a horizontal position; should the ventilation be only through the wall, incline the pipe in the direction away from the fan and use PER with a small sill drip on the façade. Should the fan be connected to a vertical pipe, a condensate drain should be installed at the lowest point of the pipe with a stench trap so that the condensate cannot flow through the fan. The same rule holds true when using the TD, RM, RK and TDM, etc., pipe fans with a disk valve. The position of the fan or disk valve should be chosen with respect to the requirement for ventilating the room, i.e. on the opposite side of the room with respect to the air intake (the intake point is usually a joint under the door) and not above the source of steam.

Residential areas
For residential areas, the same holds true to a lesser extent as for bathrooms, with the sole difference that the relative humidity does not reach the bathroom values in small kitchens and bathrooms.

Commercial buildings 
Similar measures are used here as in the preceding case. We recommend using types with an A/B rotor wheel according to the need for the industrial HCB/TCB axial-flow fans, with the motor always in a downward direction so that condensate does not accumulate in the rotor wheel hub, otherwise the rotor and its bearing would be immersed in water. In necessary cases, holes should be open in the wheel hub for draining the condensate. The same measures hold true for axial-flow fans with an HXT/TXT external rotor.

Air ducts connected to fans
must be very well insulated in places where they pass through cool areas with a danger of condensate formation (primarily passages through ventilated attic spaces, skylights, outside areas, etc.). The condensate drain must be installed at the lowest point of horizontal air ducts so that it cannot flow into the fan. The condensate drain must be installed at the lowest point of the vertical air ducts so that it cannot flow into the fan and through the room. For vertical risers, the condensate drain is usually installed at the lowest point of the duct and under the location where condensate forms (under the attic space, etc.). It is best to drain condensate with a stench trap under the rainwater pipe. We cannot recommend drainage into sewerage pipes because the tightness of the siphons cannot be guaranteed once they dry out.

Coolers, evaporators and recuperators
connected to fans and air ducts the equipment in which condensate forms during operation. This equipment is provided with orifices for draining condensate; it is best to connect them through stench traps to rainwater pipes. We cannot recommend drainage into sewerage pipes because the tightness of the siphons cannot be guaranteed once they dry out. Should such installation be necessary, the drying of the siphons must be checked. It is also necessary to adhere to the diameters of the connections for draining the condensate and the sufficient height of the water column. Mounting a siphon directly under the equipment may cause water to flow out of the equipment.

Design measures
It is necessary to adopt measures at the level of the expert design of the equipment to prevent condensate formation in places where the equipment and structures might be damaged. The equipment must be designed so that the condensate is collected and drained to appropriate places and in a controlled manner.

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