Heat Recovery - Auxiliary Condenser

An auxiliary condenser can be added to a chiller to capture "waste" heat rejected from the chiller's condenser. The auxiliary condenser scheme is similar to the double-bundle or 2-condenser system except the auxiliary condenser is typically smaller than the main cooling (tower) condenser. This recaptured energy is often used to heat water for domestic or process use. An auxiliary condenser is simply another smaller condenser bundle added to the chiller. A portion of the hot condenser gas migrates to this device heat the water flowing through it. Unlike the "double-bundle" method of heat recovery, however, there is no modulating control to regulate the amount of heat rejected. Consequently, the auxiliary condenser simply captures heat at whatever temperature level the cooling condenser is operating.

The best auxiliary condenser applications show extremely fast paybacks. These include preheating water for use in hospital laundries, domestic hot water for hotels, and boiler feed water for process applications.

Relatively low temperature water is produced by the auxiliary condenser. However, unlike a double bundle condenser, the kW per ton actually goes down when the heating water is being produced. While a chiller can be field-retrofitted with an auxiliary condenser, it costs less if it is included when the chiller is first ordered.