Air flows and adjustments

A properly adjusted ventilation system is an important prerequisite for effective energy use in a building. In conjunction with the installation or alteration of the ventilation system, it must always be adjusted. Its adjustment and air flows are then regularly inspected during each mandatory ventilation inspection (which in the case of houses is only conducted in conjunction with a new installation). Properly made adjustments reduce the risk of poor indoor climate, noise from the ventilation system and problems with damp or radon.

Flows that are too low have an adverse effect on not only the indoor climate, but often also the balance between the flows. If the ventilation system has mechanical supply and exhaust air with heat recovery, the recovery will be adversely affected if the air flows are incorrectly balanced. An exhaust air flow that is too high lowers the temperature of the supply air, which must then be increased with purchased energy. An exhaust air flow that is too low can result in excess pressure in the building, which can cause damp and mold problems.

If the air flows are incorrectly adjusted, there is a substantial risk of these problems being compensated by increasing the temperature, in either the room (via the radiator system) or the air supplied by the ventilation system. Air flows that are too high can also cause draughts, which are often compensated by increasing the temperature of the supply air. More heat must be added, which results in increased energy use.

Unnecessary pressure drops increase the need for electricity to drive the fan. The principle for adjusting the ventilation system, in simple terms, is for the air vent (used to adjust the amount of air) furthest from the fan to have as small a pressure drop across it as possible. The setting of this air vent affects the pressure throughout the entire system. Sometimes, it can be unnecessarily high, in which case the fan must work extra hard to push in, or suck out, the air all the way through the system. This, in turn, requires more energy, and for no good reason.

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