Recovering Heat from Commercial Kitchen Exhaust

Commercial kitchens consume more energy per square foot than any commercial building space. The equipment used in these kitchens—gas ranges, ovens, broilers, deep fryers, gas-fired char broilers, and steamers—produce excess heat as well as combustion gases, particulates, and grease that need to be removed by commercial kitchen ventilation (CKV) systems. Some large institutional kitchens vent over 30,000 cubic feet of air per minute (cfm), and all of that air has to be replaced by make-up air that must be heated or cooled, depending on the climate, significantly raising the overall energy consumption of the restaurant or cafeteria.

The Halton HRU uses a fin-tube heat exchanger that captures heat in the exhaust duct and transfers it to another heat exchanger in the make-up-air ducts using a closed glycol loop. Sensors in the ducts determine whether or not the make-up air needs to be preheated. If not, an optional configuration can divert the glycol loop to heat domestic hot water. According to Jeff Martin, developer and owner of Martin Air System, the large coil can efficiently heat water to temperatures approaching 110ºF–140ºF (60ºC).