Thos. Somerville Co. 24 Irongate Drive Waldorf MD 20601 is now a regional industry leader in the distribution of plumbing and HVAC supplies in the Mid-Atlantic United States. Areas Served: Thos. Somerville operates out of 21 trade locations 10 retail plumbing and HVAC stores and a central distribution center with locations across the Mid-Atlantic United States. What Brands Does Thos. Somerville Co. Sell? Thos. Somerville Co. carries name brand HVAC products from Atco Acme Bacharach Beckett Bell & Gossett CSI Daikin Dayton Diversitech Fieldpiece Grundfos Hart & Coolet Hartell Honeywell Lenox Little Giant Lux Modine Nibco Panasonic Taco Viega Watts as well as many others.