Granite Group 1035 Westford St Lowell MA 1851 is a wholesale supply house of plumbing and HVAC equipment parts and supplies. Areas Served: The Granite Group has plumbing and HVAC supply houses throughout the Northeast. What Brands Does The Granite Group Sell? The Granite Group offers name brands like Mitsubishi Maytag Gibson Miller Honeywell Ducpac Buderus taco Grundfos as well as many others.