74/Plumbing Engineer September 2020

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ary and I have covered a lot of ground in our last six articles in this magazine. We focused on transforming high performing building hot water systems fired with hybrid solar thermal and heat pumps. We explored how smaller pipes deliver hot water faster without excessive pressure loss. We looked at how much energy waste can result if you skimp on pipe insulation. Now we want to get real - namely to design and install a real Practically Perfect Plumbing (PPP) system in a multifamily building. We have an amazing example for you - one that is unfolding even as we write this article. A new construction plumbing design opportunity In our first few articles, we explored how we designed and built the hot water heating systems for the award win- ning Solara NetZero multifamily project near Schenectady, NY. Extensive flow monitoring helped us use fundamen- tal physics and Gary's research to choose pipe sizes that would minimize energy and water waste and get hot water to the taps really fast. Once built, we confirmed our suc- cess with more testing and discussions with tenants and maintenance personnel. As word spread about our success at Solara, visitors came to visit and talk to us about the design of the build- ings and our hot water plumbing approach. One visitor was a manager of reconstruction work at a large affordable housing company with tens of thousands of apartments in many states. We really hit it off and eventually convinced he and others in the company to consider applying the concepts to one of their new seniors-only building projects near Utica. We were elated but wow - challenged to say the least. When we jumped into this project, the concrete pad had been poured and contracts let for the first of three build- ings; we were kinda late to the party! What we discovered in the mechanical drawings was no surprise (in part, because the design was a carbon copy of the plumbing already installed in the three earlier buildings at the site). The design for the 35 unit building as below featured large diameter hot water pipes (2- to 2") and a vast traditional trunk/riser/branch pipe network. Our monitoring at those earlier buildings had revealed flow maxima of substan- tially less than 3 gpm at the 99% percentile point. Trunk lines 2-" in diameter seemed excessive, to say the least.

Practically Perfect Plumbing In Multifamily

By Pete Skinner & Gary Klein

Our theories applied on a three-floor multifamily project