ERV vs HRV: what is the difference?
Both systems recover energy from outgoing air, but they handle moisture differently. Here is what that means in a real home.
HRV and ERV are both forms of balanced mechanical ventilation that can recover energy from outgoing air. The key difference is what happens to moisture as well as heat.
What is an HRV?
HRV stands for heat recovery ventilation. Warm, stale indoor air passes through a heat exchanger as fresh outdoor air enters. Heat is transferred between the two air streams without the air streams normally mixing directly.
The system recovers sensible heat. It does not intentionally transfer moisture through the core in the way an ERV is designed to.
What is an ERV?
ERV stands for energy recovery ventilation. An ERV can recover sensible heat and, depending on the technology and operating conditions, transfer some moisture as well. This can affect indoor humidity and the energy needed to condition incoming air.
So which one is better?
There isn't a universal answer. The appropriate system depends on the building, climate, occupancy, moisture loads, desired control strategy and the equipment available.
Think about the whole system
- How much ventilation airflow does the home need?
- Where will fresh air be supplied?
- Where will stale air be exhausted?
- What are the main moisture sources?
- How will bathrooms and kitchens be extracted?
- How will filters, controls and maintenance be handled?
Don't confuse heat recovery with moisture removal
A recovery ventilator is primarily a controlled ventilation system. It does not automatically replace a dedicated dehumidifier, and the presence of an ERV does not mean a wet bathroom can be ignored.
Likewise, an HRV does not automatically solve every condensation problem. If airflow is too low, the system is poorly balanced, or there is an unusually high moisture source, the building can still experience condensation.
What about Auckland homes?
Homes in Auckland can experience changing outdoor temperature and humidity through the year. That makes system selection and control important, but the right solution still depends on the individual building rather than the city name alone.
Sterling can assess an existing ventilation system or discuss the requirements of a new installation before recommending an approach.