What type of HRV system can cause an air pressure difference between the inside and outside of the building?

What type of HRV system can cause an air pressure difference between the inside and outside of the building?

• A. Unbalanced system
• B. Balanced system
• C. Hybrid system
• D. Staged system

Answer: (A)

An HRV that isn’t balancing the air coming in with the air going out can create a pressure difference between inside and outside. When the volumes don’t match, the indoor air pressure shifts: if more air is exhausted than supplied, the space falls into negative pressure and outdoor air leaks in through cracks and infiltration; if more air is supplied than exhausted, the indoor pressure rises and air pushes out through leaks. This is why the system would cause a pressure difference. A balanced HRV, by design, brings in and exhausts equal amounts of air, keeping indoor pressure close to outdoor and minimizing unintended infiltration or exfiltration. The other terms describe different control approaches or configurations that don’t inherently imply a persistent pressure difference the way an unbalanced setup does.

An HRV that isn’t balancing the air coming in with the air going out can create a pressure difference between inside and outside. When the volumes don’t match, the indoor air pressure shifts: if more air is exhausted than supplied, the space falls into negative pressure and outdoor air leaks in through cracks and infiltration; if more air is supplied than exhausted, the indoor pressure rises and air pushes out through leaks. This is why the system would cause a pressure difference.

A balanced HRV, by design, brings in and exhausts equal amounts of air, keeping indoor pressure close to outdoor and minimizing unintended infiltration or exfiltration. The other terms describe different control approaches or configurations that don’t inherently imply a persistent pressure difference the way an unbalanced setup does.