Impact on the Rest of the HVAC Design & engineering

Where heat recovery will be used for heating, the chiller should tie into the boiler return. A tertiary loop is recommended so the chiller heat recovery temperature range can be different from the boiler loop range. The flow rates for the boiler and the heat recovery will most likely be different as well. A tertiary loop also allows the pressure drop through the heat recovery chiller to be avoided when heat recovery is not possible.

Most heating systems are designed for 170°F average water temperature. The use of heat recovery will require the heating system to operate with water in the 105 to 115°F range. Whereas single row heating coils in terminal heating units would have worked with a conventional design, now 3- or 4- row heating coils may be required. These coils will add to the capital cost of the project. Further, they will increase the fan static pressure drop every hour the fan system operates.

Domestic hot water systems range from 120°F for showers, baths, etc to 140°F for kitchens. These temperatures exceed the capabilities of a heat recovery chiller, however, a heat recovery chiller can be used for preheating. When heat recovery is used for domestic hot water, local codes may require an isolating heat exchanger.