HPAC Magazine

Shower Power

More water and less resistance are the keys to achieving good pressure.

September 1, 2012   By Steve Goldie

I enjoy a good shower, as do most people. Whether it is after a long day filled with hard work or a short night filled with too little sleep and too much wine, there is nothing quite like a nice hot shower to rejuvenate and restore us to some semblance of humanity. It is one of those simple pleasures of life that separate us from the beasts. Believe me, take away the nice hot showers and most happy households will rapidly descend into chaos. I am convinced it was a camping trip with a bunch of teenagers and no hot showers that inspired William Golding to write “Lord of The Flies.” Besides the hot water, the other essential element to a satisfying shower is good water pressure, and lack of good pressure is one of the most common complaints we hear about.

A typical residential plumbing system is designed to operate at between 40 and 70 pounds per square inch (psi) of pressure. In a municipally delivered system, water pressure is maintained through a series of pumping stations, elevated water reservoirs and water towers. It is pumps and/or gravity that provide the necessary pressure at a rate of 1 psi for every 28 inches of elevation (water column), resulting in just over 64 psi at the bottom of a 150-ft. water tower. Water pressure at any individual home or business is determined by its proximity to the pumping station and/or the water tower (or reservoir) serving it. For residences on private wells, water pressure is maintained via the well pump, usually in conjunction with a pre-charged pressure tank.

When your customer is not getting enough water at the showerhead (or heads) the complaint is always, “we don’t have enough pressure,” but is a lack of pressure always the culprit? The showerhead needs two things to perform effectively, it needs sufficient pressure and it needs sufficient flow to maintain that pressure. Although both problems result in the same symptom, the solution depends on properly identifying the cause, is it insufficient flow or insufficient pressure?

Verifying the static pressure (pressure when all taps are turned off) is as simple as attaching a pressure gauge at any point in the system. Gauges that attach to a hose connection are perfectly suited to this application. Most well systems should have gauges already installed making verifying the pressure even simpler. If the static pressure is lower than 40 psi then the problem is indeed a low pressure problem.

Booster pumps are available from many manufacturers in various sizes, and if a simple boost in pressure is all that is needed, your local wholesaler should be able to help find one that is right for your application. To size them properly you need to know what the required boost is, say from 35 psi to 60 psi, as well as how much flow is required in gallons per minute (gpm). In recent years we have seen variable speed motors become increasingly available. These are also now available on pressure boost pumps, increasing efficiency and delivering very reliable results.

If low pressure was always the culprit, the solution would always be the same; install a properly sized pump, adjust the pressure switch and everyone is singing in the shower. However, as I have already mentioned, ‘pressure’ problems are often actually a result of inadequate flow.

Let’s go back to our pressure gauge. When we check the pressure with all the taps turned off everything looks good. Now, have a look when one or two taps or fixtures are turned on. If the pressure drops dramatically, then the system piping is not able to allow sufficient flow to maintain adequate pressure. The water service coming into the building may be undersized, or in an older building scale or corrosion may have built up, choking off the flow. The same may be true of the distribution piping within the building; it may be undersized or obstructed. Providing the correct solution requires identifying where the deficiencies are located.

Upgrading the incoming water service may be the best or most obvious solution. This likely requires trenching or torpedoing a new line in from the municipal service. If this option is not possible or desired, a pressure pump system can be installed. These are very similar to those installed on private well systems, with a reservoir tank taking the place of the well (or lake). Private well and pump systemsinclude: a well (the water source), piping from the well to the building, a water pump, and a water pressure tank to which building water supply plumbing is connected. When water is turned on at a fixture in the building, compressed air in the water pressure tank pushes water out into the building’s water supply piping and to its plumbing fixtures. The reservoir tank is not the same thing as the pressure tank, the pump cannot pull water through the service any faster than the service can already provide. The reservoir tank provides a ready supply of water for the pump to pull from, enabling the requisite boost in pressure and flow.

Too many times I have seen where a homeowner has paid good money for a pressure pump system only to have the same problem that existed before the system was installed. The reason; no reservoir tank was installed. The key factor is providing enough flow to sustain the required pressure at the fixture. If you have a shower system that requires six gpm and the water service or well is only providing four gpm, there is no pump in existence that can fix the problem by itself.

I know that many contractors do great work and properly size their systems. Shower systems today are very different from those of just a few years ago, multi-spray heads and large rain flow heads seem to be the norm rather than the exception. Dealing with pressure and flow problems in an older house is understandable, but having to live with it in a brand new home is never acceptable. Main supply lines and risers, both hot and cold should be 3/4″ minimum, with 1/2″ lines only used as feeders to individual fixtures. Home run systems are more popular than ever and offer very good results. A 3/4″ pipe has almost 50 per cent more circumference and nearly 132 per cent greater cross-sectional area than a 1/2″ pipe. This means much more water, less resistance and therefore, much more pressure and flow at the fixtures

The difference in cost between doing it right or not is but a proverbial drop in a bucket, and no homeowner should hesitate to pay if they understand the benefits. It is a small price to pay for the ability to shower unencumbered without worry about who is flushing what.   

Properly designed, installed and maintained plumbing systems are essential to our domestic happiness and comfort. Who knew the humble plumber was responsible for keeping our civilization civilized? I think I am on to something here, it might just be a good hot shower is all that is keeping us from sliding into another dark and medieval age.   

Steve Goldie worked as a plumbing and heating contractor prior to joining Noble as manager of the heating department. In his current position Goldie focuses on product specification and system design solutions. He can be reached at sgoldie@noble.ca.

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