What would plumbing look like if it were designed only for superior performance and durability? What if politics and designing for the lowest common denominator didn’t enter into the thinking?
Let’s start by thinking about what we want the plumbing to do. Assuming now that we’re talking about the hot water system, (because we LIKE hot water) we want the plumbing to deliver clean hot water quickly, in the amounts we need and with little or no waste of either energy or water. We also want the system to behave nicely for an extremely long time, with not a single problem. So, no leaks, no noise and plenty of hot water. Oh, and we want it to be adaptable to future changes in the building.
What would such a system look like? To start, we’d need to know the flow rates of the fixtures. We’d find the lowest flow rates we could that do the job at hand. That might be a 1.5 gpm (or lower) showerhead and kitchen sink and .5 (or better .35) gpm lavatory sinks. We might have appliances like clothes and dishwasher that heat their own water, so no hot line would need to be run to those places. We’d also need to know the pressure in the lines when no water is moving; called static pressure. In addition to knowing those two things, we’ll need to figure out how long the piping runs need to be.
Plumbing design with one main manifold, or possibly distributed manifolds will determine line length. Now, finally, we can size the tubing. A good (and free) tool for this is the System Syzer by Bell and Gossett. It is designed for copper, which likes water flow up to four feet per second. PEX can take ten feet per second if you have adequate pressure! One last thing to consider is water quality. Say it’s acidic. You wouldn’t want to use copper in that case as it won’t hold up. PEX is better for aggressive waters.
Modern plumbers seem hardwired to build straight and square. Modern materials, like PEX tubing don’t need that. They work best using the most direct route and the fewest fittings, so you suffer the least pressure drop, (friction losses) possible. Everything we can do to reduce the volume of water in the lines and decrease friction losses will help with better and faster hot water delivery with the least waste. Pressure compensating aerators and showerheads will help further, by keeping flow the same even when someone else uses water in the house.
One more thing modern plumbers do is to insulate as little of the plumbing as possible. We operate under the misguided idea that it’s not cost effective. Let’s look at this from another perspective. How cost effective will it be in 25 or 50 years? How long will this plumbing be in place? We can be pretty sure that energy and water will never come down in price, so let’s design the system to not need updating during its life. Insulate all of the hot plumbing and even the cold plumbing if it’s installed in a humid climate. This way, we save BTUs and prevent condensation damage, along with improving system performance. And as long as we’re insulating, let’s use thick insulation. A good rule is to use the same thickness as pipe size. Half inch tube gets half inch thick insulation, and so on.
Part of the fun in this is when you understand that the physics say you might be able to use ¼” or even 1/8” tubing to supply fixtures! Such small tubing with so little water in it means you won’t need to wait long at all for hot water to arrive. Yay! It also means the system will cost less than “normal” plumbing as you’re using fewer feet of smaller tubing, which will take less time to install; you’ll be saving gallons and BTUs every day; and you’ll be saving time, not waiting long for hot water to arrive… for as long as you live in the house!
The fittings pictured above are officially called Swoops. A friend, Gary Klein, figured out that fittings like this add almost no friction loss to plumbing, which may let us downsize the pipes. He decides to name the fitting “Swoop”. If you’re installing copper plumbing, this is good. If you’re working with PEX, just bend the tubing as needed with bend supports or long turns and avoid as many 90 degree fittings as possible.
Not many decades ago, we used to design houses so all the wet rooms were fairly close together. This allowed the plumbing and mechanical systems to be rather compact, saving money and increasing efficiency. More recently, we seem to have forgotten how to do this. Wet rooms now are spread out all over the place, as far away from the water heater as possible. Still, “central core” plumbing is a concept to keep in mind when remodeling or building from scratch as it can dramatically increase performance of plumbing and other systems.
Taking it one step further, if you do central core and build a small mechanical room where the machinery of the house lives, it would be pretty simple to build spare ports into the plumbing so more fixtures would be easy to add later on. I’ve also found that it’s possible to build chases where small plumbing can go, like oversized, hollow baseboard or crown molding. This makes adding or servicing the plumbing far easier than having to rip out sheetrock or notch studs.
This is just an overview of some of the possibilities, but you see that we can do a lot to make plumbing serve our needs better and more efficiently if we can just drop some of the commonly accepted limitations.
Looking back over my working life of nearly 50 years, it seems clear that self sufficiency has always been the best way for me to be useful. Now, mix in a strong interest in water in its many forms and the wide world of animals and you'll know what's important to me.