The H+L vacuum regulated ventilation (VRV) system combines two important functions: ensuring a good climate and providing sufficient fresh air in the case of a power cut.
A good ventilation system in pig housing must provide sufficient fresh air, maintain the temperature in the pig house and also prevent draughts. In practice, preventing draughts is often the most important and most difficult task. In the VRV-ventilation, the air circulation speed is regulated by the opening of a pneumatically controlled valve.
The regulating mechanism of the VRV system works as follows:
The ventilation level is determined by the difference between the indoor air temperature and the target temperature. The speed at which the air should be drawn in is determined by the difference between the outdoor temperature and the target temperature. By measuring the vacuum it is possible to calculate the actual air flow rate (Bernouilli’s principle). The air inlet valve is pneumatically moved into the right position to achieve the desired flow rate of the incoming air. Utilization of the Coand? effect ensures that fresh air is mixed with the indoor air without creating a draught.
Safety in the case of a power cut
In the case of a power cut, the valves open to allow fresh air to flow into the pig house. The valves in the VRV-ventilation are big enough to ensure a sufficient supply of fresh air.