ERV vs. HRV
ERV and HRV products provide superior indoor air quality and save energy. S&P offers both technologies. Our goal at S&P is to make a proper selection easier by giving you all the facts. Ultimately whether you need an ERV or HRV, you know you want a balanced ventilation system. A balanced ventilation system introduces the same amount of fresh outdoor air as the amount of air being exhausted from the building.
Note: The following information applies to mechanical ERVs & HRVs using cores.
- Sensible Heat: The amount of energy involved to raise or lower the temperature of air not including any energy required to cause water vapor to change state.
- Latent Heat: The amount of energy associated with the humidity (or water vapor content) of an air stream. A drier air stream contains less latent heat and will impose a smaller latent load on the air conditioner.
- Enthalpy: The total amount of energy contained in air, the sum of sensible and latent heat.
- Balanced Ventilation: A ventilation strategy with both an exhaust and supply/make-up air blower that does not pressurize or de-pressurize a building.
- Air-to-Air Heat Exchanger: Generic term for technologies designed to transfer heat – and sometimes moisture – between two air streams.
- Heat Recovery Ventilator – HRV: An air-to-air heat exchanger that transfers sensible heat only; no humidity (latent heat) transfer occurs between the two air streams.
- Energy Recovery Ventilator – ERV: In Cold Weather, some of the humidity in the inside air is recovered – along with its latent energy. Non-enthalpic heat recovery systems lose that latent energy.
Heat Recovery Ventilators (HRV) and Energy Recovery Ventilators (ERV) are air-to-air heat exchange systems that reduce energy consumption when heating or cooling. HRVs and ERVs are similar in that they both:
- Improve Indoor Air Quality
- Moderate extremes in ventilation temperature
- Use heat that would otherwise be lost with the exhaust air in the winter
- Provide necessary fresh air while pre-cooling in the summer
ONLY ERVs have the ability to transfer water vapors or moisture so they:
- Help prevent over-drying of the home in colder seasons
- Lessen the demand on the air-conditioning system in warmer seasons
- Are typically 3x more energy efficient in the summer than products (or units) that transfer only heat (HRVs)
In general ERVs are recommended for most residential and commercial applications, regardless if they are located in colder climates or warmer climates. The choice you make depends on if you want to transfer just heat like in exhaust from an indoor hot tub or pool room or heat & humidity, which is beneficial to optimize both comfort and energy savings in virtually any other application or climate zone.
The choice you make depends on if you want to transfer just heat or heat & humidity, the type of core in the unit, and other components of the unit. If you are deciding between an S&P HRV or ERV here is what we recommend:
- Our HR Series Heat Recovery Ventilators are for residential use only. The HR Series utilize polypropylene cross-flow type heat recovery cores designed to transfer the heat between both exhaust & supply air streams without allowing any contamination or mixing of both air streams to maximize the efficient and improve indoor air quality.
- Our TR Series Energy Recovery Ventilators are for residential or light commercial use and can be used in ALL climates. The exhaust and supply air streams are directed through a highly developed "air-to-air" energy exchange core. The air streams are physically separated by many layers of "plates" so there is no mixing or contamination of the fresh air. The plates are made of an engineered "resin" material that simultaneously transfers heat by conduction and humidity by attracting and moving water vapor from one air stream to the other. Unlike other ERVs on the market, no mechanical or electrical defrost system or drain pans are required! Since the TR does not require a defrost system or drain pan it can be installed in any orientation and in unconditioned spaces like attics and garages.
- Our TRC Series Energy Recovery Ventilators are for commercial use feature the same enthalpic cores as our TR models. These commercial, indoor ERVs moderate extremes in both temperature and humidity, creating a comfortable indoor environment. The unique moisture transfer capability of the S&P core also eliminates condensation and frost build up in most applications. Unlike other ERVs on the market no mechanical or electrical defrost systems are needed, which means higher heat recovery efficiencies, easier installation and more reliable operation.