Plumbing Engineer September 2020/77
dropped ceiling on the second floor. This approach would allow installation of a single trunk in either direction with very short branches to six stub manifolds feeding a triple stack of apartments as illustrated in this diagram. These twigs are short because they cross from the manifolds through the trusses and up (or down) to the fixtures. The longest ones in this design approach 20 feet with time to tap of less than 10 seconds. The Takeaway We are really delighted that we will soon have 10 build- ings in upstate New York with compact plumbing and 3/8" tubing home runs for hot water. The three new buildings near Utica will be identical to earlier ones at the same site using the original WSFU based distribution system. We will be doing in-depth flow rate, pressure and hot water time to tap assessments along with hot water use and recirculation heat loss analyses. Discussions with the plumbers at both Solara and the Utica jobs will allow us to recommend faster installation techniques. These data will help us document benefits (and costs) of our practically perfect plumbing. l Peter Skinner, P.E., owner and founder E2G Solar LLC, designs, installs, repairs, researches and teaches about residential and commercial solar thermal systems and their integration with heat pump systems in New York and neighboring states. Skinner previously worked for the NYS Attorney General's Environmental Protection Bureau supervising a team of scientists on environmental litiga- tion, legislation development and policy development for 33 years. He is a NYS registered professional engineer and has worked as an engineer, educator and legislative and policy advocate in the environmental field for the past 50 years. Skinner is an engineering graduate of Lehigh University and Rensselaer Polytechnic Institute. Gary Klein, president of Gary Klein & Associates, Inc., is intimately involved in energy efficiency and renewable energy, with an emphasis on the water-energy-carbon connection. installation competition between the two styles with seven twigs. He seemed convinced that the branch and twig style would take less time and look better (he preferred rectilin- earity, a throwback to his copper pipe days). With the clock ticking, he and his colleague pulled the seven twigs one at a time from a big roll on the floor, affixing the twigs to truss members with plastic talon-type nailed hangers. The twig pulling part was easy and only took a few minutes. The talons, however, were problem- atic, forcing the fellows to mount and move step ladders every 3 feet for each twig along its length and awkwardly swing the hammer among the mechanical stuff and wood truss bracing; 35 minutes later they were done. We restarted the clock for their trunk and branch style. Instead of PEX on a roll, they used " sticks of PEX with Viega PureFlow type press fittings. The installation pro- ceeded efficiently but the nail type talon hangers posed the same hammer problems and less than half of the piping was rectilinear. More time was required for drilling holes in the studs and plates. In the end, this style took the same amount of time. I came away with a heightened apprecia- tion for the need for better hangers and wiser installation procedures. Back at Solara the next day, we witnessed that same process in action by a different crew who accomplished this job with four twigs in 15 minutes. They used a mix of talons and wire ties for aligned twigs, sometimes with screws instead of nails. With practice, they might be able to do the job even faster as they gained familiarity with the apartment layouts. The approach at the new buildings near Utica could be even better had the utility room been located in the middle of the building and the valved manifolds located above a
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