HYDRONIC PLUMBING AND HEATING SYSTEMS; NAMELY, COMPLETE IN-FLOOR HEATING AND SNOW MELTING INSTALLATIONS SOLD AS A UNIT, CONSISTING OF PEX-A and PEX-C PIPE, PIPE SPACING AND LOCATING TRACK, PIPE SPACING AND LOCATING MATS, EXPANSION STRIPPING, HEAT TRANSFER PLATES, PIPE COUPLINGS AND ADAPTERS, MIXING VALVES, MIXING VALVE MOTORS, MIXING VALVE CONTROLLERS, DISTRIBUTION MANIFOLDS, SUPPLY MODULES, BALANCE/RETURN, ZONE DRIVE MOTORS, THERMOSTATS, AND SET-BACK THERMOSTATS; PIPE, MANIFOLDS AND FITTINGS THAT ARE USED FOR THE DISTRIBUTION OF POTABLE HOT AND COLD WATER TO PLUMBING SYSTEMS, INCLUDING WATER CLOSETS, SINKS, SHOWERS, BATHTUBS, LAVATORIES, HOSE BIBS, WATER HEATERS, BOILERS, AND WATER SOFTENERS