Review Heat Recovery Systems vs Energy Recovery Systems
There are two types of energy-recovery systems: heat-recovery ventilators (HRV) and energy-recovery (or enthalpy-recovery) ventilators (ERV). Both types of ventilators include a heat exchanger core, one or multiple fans to push air through the mechanical equipment, and some other controls. The most obvious difference between a heat-recovery ventilator and an energy-recovery ventilator is the way the heat exchanger core works. In an energy-recovery ventilator, the heat exchanger transfers a certain amount of water vapor in addition to heat energy. A heat-recovery ventilator only transfers heat and not water vapor.
The part of the country in which you are building the structure will dictate what type of unit that is right for your needs. Generally speaking, HRVs are usually recommended for colder climates that have longer heating seasons. Alternatively, ERVs are used for warmer, more humid climates with long cooling seasons.
Take the Time to Locate Exhaust Points
Since the idea is to remove humid, old air from the commercial structure, locate the stale air exhaust points in each bathroom, kitchen, utility room, and other high moisture areas in the commercial structure. If you are working with new construction and are still in the design phase, use your detailed plans to locate all exhaust points. This allows heat recovery from areas of the building where humidity and odors are most abundant. The heat recovery system can replace spot ventilation (exhaust) fans in some of these rooms to save money and provide a more pleasant environment. Any room that has a function where humidity would be created by occupant activities, a heat recovery system will be helpful. An exhaust point that is located near the kitchen area should be at least six feet from the cooking surface. This exhaust point is intended to remove general moisture in the air and cooking odors.
Be Sure to Locate Fresh Air Supply Points
In order to mix fresh air throughout the building, supply points should be positioned a considerable distance from the exhaust points. Bedrooms and living rooms are good choices. Although the incoming fresh air has been tempered and warmed by the heat exchanger, it’s usually slightly below socially normal room temperature. Taking into account where the occupants will be sitting or occupying the space will help avoid having the air blow directly onto them. It is recommended to place the incoming vents high on a wall, so it will mix with warm air and not be noticed by the occupants.
Creating a Dedicated Duct System is Recommended
Most experts agree that it’s best for an HRV to have its own dedicated duct system. If the building has hydronic heat or ductless heat pumps, that’s the only choice. In this case, the HRV mixes the air throughout the building. However, buildings with forced air heating and cooling systems can use those ducts. This saves money on material and labor and offers great distribution of fresh air. Integrating HRVs with forced air systems requires careful planning, review from an MEP engineer, proper controls, and sound installation practices.