Why Logic Plumbing Beats Home Run and Trunk and Branch

Tim Ward August 8, 2018

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For residential plumbers, there have been two schools of thought for plumbing a house: home run and trunk and branch. Both have their positives and negatives, depending on what you’re trying to accomplish with the plumbing system.

However, you may not know there’s a new (and smarter) way to design and install a residential plumbing system that installs faster, uses less materials, requires fewer connections, minimizes your liability and operates more efficiently.

It’s called Logic plumbing.

A Logic plumbing design can only be used with PEX piping, but since PEX is now used in more new-home construction than copper and CPVC combined, you’re most likely already using it. (And if you’re not, you need to check it out. PEX is highly durable, flexible and more cost-effective compared to copper and CPVC.)

The Logic approach leverages the flexibility of PEX pipe to minimize connections and reduce potential leak points while also incorporating multiport tees located near fixture groupings to both limit the amount of pipe and connections needed while also improving installation efficiencies and system performance.

What’s a multiport tee?

I’m sure right now you’re wondering, “What’s a multiport tee?” It’s essentially a bunch of tees all molded together to create one long tee with multiple outlets. This innovative product minimizes connections and is the heart and soul of a Logic design.

For example, six regular tees will have 18 connections, but a flow-through multiport tee with six outlets will only have eight connections (six connections for the ports, a main flow-through inlet and a main flow-through outlet). Think about how much faster you could install a system when you’re making half the number of connections.

And get this — while multiport tees may resemble a manifold, they have the benefit of being hidden behind walls without the need for an access panel. Yes, you heard that right. No need for an access panel, minimizing costs and labor to help keep your projects on schedule and on budget.

Multiport tees are made of engineered polymer (EP), a thermoplastic material that has been used in plumbing applications for more than 20 years. EP has superior mechanical, chemical and thermal properties that provide dimensional stability in demanding applications, including areas of high stress, heat and moisture.

And, like PEX, the EP material in multiport tees resists corrosion, pitting and scaling, so it creates a highly durable system that’s engineered to last. Best of all, multiport tees (as well as all EP fittings) are approved for direct burial in the soil or concrete slab, so they are ideal for in-slab plumbing applications.

The Logic layout

So what exactly is a Logic plumbing layout? It’s quite simple: a main line connects to a multiport tee with distribution lines going out from the tee. These individual lines extending from the single multiport tee provide water to all fixtures in a single or adjacent grouping.

This design uses significantly less pipe than a home-run layout, with just a few more connections. Plus, it requires considerably fewer connections compared to a trunk-and-branch installation.

For example, a 2,300-square-foot, two-story home using a Logic design requires only 637 feet of pipe while a home-run system uses 1,515 feet of pipe. That’s more than twice the amount of piping necessary.

In addition to the added costs required to install all that extra pipe, the system performance is also greatly reduced due to added pressure loss and longer wait times for hot water. Plus, all the extra pipe can lead to issues isolating hot and cold water lines. This increases heat transfer and energy inefficiencies within the plumbing system.

And, while it’s true a Logic installation uses slightly more connections than a home-run layout (59 vs. 48 in the 2,300-square-foot, two-story home example above), the amount of pipe savings is significantly more beneficial with the labor and material savings you get with less pipe to install (not to mention the efficiency of the system).

A Logic layout also installs much faster compared to a trunk-and-branch system due to the vast reduction in connections. With the two-story home example above, a Logic layout uses a mere 16 fittings and 59 connections compared to a whopping 96 fittings and 165 connections for trunk and branch. That’s six times the number of fittings and nearly three times the amount of connections!

All those added connections greatly increase your liability with more potential for leaks, plus it also limits the performance of the system with increased pressure loss.

So there you have it! Just a few “logical” reasons why you should consider a smarter approach to plumbing a home that will improve your installation times, limit your liability and offer an all-around better-performing system for the end user.