A module was developed for EnergyPlus to simulate the operation of direct-fired double effect absorption chillers. The module uses performance curves similar to the equivalent chiller in DOE-2. This type of chiller is unusual for EnergyPlus because it may be used in the same plant on both a chilled water supply branch and a hot water supply branch. The chiller has six node connections for chilled water, condenser water, and hot water, and can provide simultaneous heating and cooling. During simultaneous operation, the heating capacity is reduced as the cooling load increases. Also developed for use with the absorption chiller module were equipment performance curves for a range of direct-fired chillers sold by four manufactures.