What is an ERV?
ERV is short for Energy Recovery Ventilator. Some common variations would include ERV air exchanger and ERV ventilation systems. How does it work? Two air-streams travel in opposite directions; one at the temperature of 0ºF, and the other at 70°F. Most would assume each air stream would balance out to the average of 35ºF each.
The air-streams actually switch temperatures; the 70°F becomes 0ºF, and the 0ºF becomes 70°F. This is the core theory behind Energy Recovery AKA — Air Exchange.
How Do ERV Systems Work?
An ERV operates on the basis of this air-to-air exchange theory. A spinning wheel, or stationary core device utilizes the counter-flow of air to remove the stale air from inside a building, while retaining air temperature.
However, an ERV wheel or core cannot produce a 100% theoretical energy recovery result. Therefore, they are rated to return a percentage of effectiveness (Certified By AHRI) depending upon your environmental conditions. These percentages will vary under different environmental conditions, and are usually defined as summer and winter conditions. An ERV Wheel offering an 80% Energy Recovery result (14ºF ÷ 70°F = 0.8 — equivalent to 80%). This 80% recovery introduces a mild 56ºF to mix with the indoor air, instead of 0ºF.
What Are the Uses of an ERV?
ERV’s can be stand alone and give minimal treatment to fresh air being introduced to the home or building. They can reduce the size of a greater dedicated outdoor air system by capturing the energy of the exhausted air.
What to know when selecting an ERV?
These will be the defining characteristics to determine the correct ERV.
- Where will the unit sit, inside or outside?
- How much CFM will be supplied and exhausted?
- Will it be part of a system or stand alone?