US Patent 7832464 Flexible HVAC module with add-on multi-zone sub-assembly

An independent mixing valve sub-assembly which includes a casing defining a cold bias inlet, a hot bias inlet and a second zone inlet and a mechanism for mechanically attaching the casing to the housing of a HVAC module with the cold bias inlet, the hot bias inlet and the second zone inlet of the mixing valve sub-assembly in sealing engagement with a cold bias outlet, a hot bias outlet, and a second zone outlet of a HVAC module, respectively. The mixing valve sub-assembly may provide one or more streams of temperature-controlled air. Accordingly, different mixing valve sub-assemblies may be attached to one universal HVAC module to provide varying numbers of temperature zones.