Ask This Old House plumbing and heating expert Richard Trethewey helps a homeowner reattach an undermount kitchen sink to a granite countertop. (See below for a shopping list, tools, and steps.) SUBSCRIBE to This Old House: http://bit.ly/SubscribeThisOldHouse Shopping List for How to Secure an Undermount Kitchen Sink: - Undercounter-mount sink clips (comes with wing nuts…