Balancing crucial to MVHR function

13th September 2022

A system must be designed, installed, and commissioned correctly to ensure a balanced system, if a system isn’t balanced correctly, it can either pressurize or depressurize the house, resulting in an inefficient system. A balanced system should produce a neutral pressure within the building thus removing the risk of air leakage through the envelope of the building. If the extract rate is higher than the supply rate, there will be a negative pressure in the house, resulting in cold exterior air being drawn in through the leaks in the building envelope.

If the supply rate is higher than the extract rate, there will be a positive pressure, allowing warm air to leak out through the building envelope. More importantly, the rate of heat exchange will be impaired if the supply and extract rates differ significantly. In the colder months when the exterior air is below freezing, a system requires some form of frost protection to prevent the heat exchanger from freezing. The issue arises when the condensation from the extracted air is cooled by the external freezing air, the condensate freezes and blocks the channels in the heat exchanger.

Most units incorporate some form of frost protection function to protect the heat exchanger from freezing. This is often achieved by slowing the supply air fan which results in an imbalance of airflow and has the effect of seriously reducing the amount of heat recovered. If this function is used for long periods, the house will get an insufficient supply of air. By contrast, our range of Brink MVHR units has a completely new intelligent frost protection system that ensures that at low outdoor temperatures the unit’s performance remains optimal and that, if necessary, it activates a standard preheater. The preheater provides a sufficient amount of heat to the incoming air to raise the temperature to just above freezing.

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