Heat Recovery Units
Some local regulations or consultants will require the fan systems to utilize an energy recovery application in order to extract exhaust heat for the heating or cooling of conditioned makeup air. These units can be selected to operate with either glycol or water heat exchanger coils.
When selecting a heat recovery unit (HRU) as part of the system, it is important to account for the additional 1.25” WG of static pressure that is encountered through the pre-filters and coils. The plenums for HRUs are double wall insulated and result in an increased footprint of the system. Access doors are built into the side of the plenum for easy access to the pre-filters for change out and to clean the coils. Light kits can be installed within the plenum/HRU unit as an additional option, as well as electrical outlets at each access door.
With regards to design specifications, the flow velocity through the pre-filters and coils is limited to below 500fpm. This allows for efficient filtering and optimal performance through the coil section. The tubing for the coils is selected as a standard to be copper, but can be changed to either aluminum or stainless steel.