HVAC parts from Grainger range from expansion valve options to LP conversion kits that can help any HVAC contractor. There are parts and adapters to install the supply return, plenum duct, fiberboard and vent racks. There are parts and adapters for the supply return, and hard-start kits for wiring large residential units. There also are plenum duct, fiberboard and vent racks for new duct work. Get all the HVAC parts you need right here.