Now Reading
Warming to the Touch
Dark Light

Warming to the Touch



Last time, we began a discussion of giving our clients the satisfying hot-water experience they crave with a review of basic design principles and coverage of a range of materials-selection issues.

Translating the good on-site positioning and great materials we surveyed in February into a luxurious spa experience requires the designer to have an advanced understanding of the technology at work in hydrotherapy as well as a grasp of the spectrum of options available to drive and control hot-water systems.

Before we address those key topics, however, it bears quick repeating that a spa’s location, size, shape and finish materials – not to mention the overall ambiance of the setting – must be well in mind as you turn your attention to the more “interactive” elements of the design.

If we do our jobs correctly in setting up our spa systems with respect to interior seating configurations, hydrotherapy action and various control features, those who dip into the warm, bubbling, swirling water will never need to consider the expertise and effort required to orchestrate the experience.


As I mentioned in my February column, the focus here is on custom, inground spas rather than those prefabricated units that are available for purchase in retail stores. In most respects, the potential for creativity and beauty in custom designs dwarfs the comparatively limited range of aesthetic possibilities afforded by portable spas. After all, a portable spa is basically a plug-in appliance, where a quality inground spa should aspire to become an integrated component in a landscape and, one hopes, a work of art.

One area in which portables are often superior to spas built on site, however, has to do with seating configurations. I commend portable spa manufacturers for the creativity and care they’ve invested in making seating arrangements that maximize comfort and hydrotherapy action, and I sincerely believe that we custom designers and builders would do well to study the ways in which quality portables accommodate the human body.

In my own work, I’ve tried to create interiors in concrete vessels that have the same level of complexity and variety. Although I believe we can accomplish great things with concrete, in all honesty I’ve never been completely satisfied with the results we’ve obtained on our more complex seating designs. As we’re reminded all too often, they can be extremely difficult to form and even tougher to finish.

That’s not to say that we’ll ever give up on concrete spas when it comes to outfitting them with comfortable seating and agreeable interior contours. Quite the contrary: We achieve a great deal with angled backs, varying bench depths, a variety of foot rests, attractive step designs and special features such stand-up hydrotherapy wells.

That said, if I discover that my clients’ needs with respect to interior seating simply cannot be achieved with a concrete shell, I’ll seek out options among custom-made stainless steel or fiberglass shells. On a recent project, for example, I designed a custom recliner with the shape based loosely on a famous design by Le Corbusier. This curved, two-person seat was made up of spaced stainless steel tubes, each approximately one inch in diameter, running lengthwise and attached at each end to a curved frame. The jest and air channel are beneath the tubes, and the whole lounge can be raised, lowered and tilted as the clients wish.

In all cases, in other words, I go to great lengths to accommodate my clients’ specific spa-seating needs. In fact, it’s not unusual for me to take a client’s physical measurements into account when designing seating depths and widths and in deciding the all-important matter of jet locations.


One of the most valuable lessons custom builders can learn from portable spa manufacturers is that hydrotherapy jets can be located anywhere in the spa, can be aimed at just about any part of the body and can provide a dizzying array of hydrotherapy effects.

Long gone are the days when all jets were set in a ring around that spa at the same level. Now we set things up with jets that work bathers over from head to toe, from the neck and the upper, middle and lower back to the calf muscles and the feet.

These systems can be set up on different plumbing loops and valved independently so the bather has the option of activating different sets of jets in varying combinations and intensities. We can create lounge areas that virtually lift the client off the seat by providing intensive hydrotherapy action from stem to stern – or we can set up wells in which sequenced jets roll up and down the body.

Another admirable feature of some portable spas is easy change-out of individual jets or, in some cases, the use of snap-in panels that contain multi-jet arrays. Indeed, today’s market is full of all sorts of gadgets and gizmos that can truly excite our clients, from jet nozzles that provide multiple hydrotherapy effects in one device to tiny jets that provide extremely light sensations – or big exercise jets that can be adjusted to provide varying levels of resistance for in-place swimming or water walking.

All you have to do these days is check out the catalogs of spa-jet manufacturers to see that the sky really is the limit when it comes to product options. But be advised: The mere fact that a product is easy to get doesn’t mean that using it effectively is necessarily easy. All of this flexibility and wide range of possibilities burdens the designer with knowing how to set up the hydraulic and pneumatic systems that run them.

Again, portable spa manufacturers put a great deal of effort into designing balanced hydraulic and air systems that support the promised hydrotherapy action – and once they get it right, they can repeat the same configurations over and over again. Custom designers and builders can’t take advantage of that production mentality, so we pretty much start from scratch each time.

If short cuts are taken, whether it’s with an inground spa attached to a swimming pool or with a portable, the lack of careful hydraulic engineering leads to poor performance and a range of problems from uneven jet action at different spots around the spa to unsafe operating conditions (in extreme cases).

Don’t ever hesitate to seek expert advice or guidance: It’s in the best interests of the companies that make jets for use in custom spas to make certain they’re being used in the right way and with the best possible results, and most of them are more than willing to pitch in and make certain you’re on the right track.

The importance of setting up balanced plumbing loops to supply spa jets, of proper sizing of nozzles and orifices and of understanding flow and pressure requirements cannot be overstated. After all, once you install the plumbing and shoot the spa with concrete, you’re married to whatever engineering you applied to the design process!


What is true for pools is even more so for spas: Chemical water treatment systems and proper filtration are absolutely essential.

There are several factors in play here. For starters, the volume of water in most spas is quite small with respect to bather load when compared to conditions found in swimming pools, for example. As a result, spa systems tend to be far less chemically stable, and water quality can deteriorate rapidly in a poorly equipped system.

In addition, the warm water temperatures cause bathers to sweat more than they would in a swimming pool and open the pores to release who knows what into the water, which further puts a strain on the system. These elevated temperatures can also cause bacteria to develop more rapidly if the system is not adequately sanitized.

Blowing It

There’s something of a debate among those who design custom, inground spas about the role of air blowers and booster pumps.

To be sure, a spa’s air-entraining system is of critical importance to the performance of a spa’s jets. Air drawn by Venturi-style injector systems add considerably to hydrotherapeutic action and have long been a staple in the hot-water business.

If a designer or builder has a tendency to deal with air-system issues later rather than sooner, there’s always the possibility of adding a blower or booster pump to juice the jet action. As someone who takes pride in his hydraulic designs and in this case has spent time thinking about pneumatic issues as well, I’d argue that blowers and booster pumps shouldn’t be necessary and are basically there to mask poor system design.

These additions work, but all you’re really doing is slapping on an energy-wasting, inefficient, secondary system that will never be as satisfying to the customer as a properly designed primary system. Venturis are wonderful devices that use basic physics to the get the job done – but you need to plumb them correctly or they won’t work well (or at all).

— B.V.B.

In my spa projects, I always upsize my filters – for two good reasons: First, they are more hydraulically efficient, which can be crucial in systems that rely on balanced hydraulics for proper jet operation. Second, larger filters do a better job in capturing dirt and oils that can aggravate water-quality problems.

Water chemistry isn’t a regular topic in this magazine, but for spas I’d say it’s as much a design or engineering issue as it is a maintenance issue. By that I mean that decisions I make in the design stage about how the water will be treated are critical – and I have a variety of options to consider. Ozone generators, saltwater chlorine generators and chlorine or bromine feeders are all wonderful devices that that can take a great deal of the worry out of spa maintenance later on.

Personally, I prefer to equip spas with ozone or chlorine-generating systems. Either of these provides extremely high quality water without the odors and other negatives associated with some other forms of water treatment. Salt-water systems in particular work out well for spas because the lightly saline condition they instill makes the water take on a noticeably soft, silky texture that enhances the sensations of the hot-water experience.

Heating is another big issue for spas. As I mentioned last time, oversized spas can be a real problem when designed and engineered improperly if for no other reason than these big bodies of water can take a long time to reach the desired temperature, chewing up valuable Btus in the process. I guarantee you that no other issue related to a spa will aggravate clients more than having to wait around for the water to get hot.

That’s why we never cut corners when it comes to spa heating. I always urge clients to invest in an upsized heater to ensure quick heat up times, at which point making a selection is a straight numerical calculation involving water volume and heater size. Beyond that, heating efficiency is the main issue, and this is where regional distinctions come into play. For example, heat pumps can be wonderful in warm climates where rapid heat-up is not a big challenge or when a constant warm temperature is desired, while in colder climates gas or propane heaters may be the preferred choice.


The list of additional options that can be included in today’s spas is so lengthy and diverse – too extensive for detailed coverage here. So let’s take a quick tour of some of the other things I discuss with my clients:

[ ] Controls: Modern control systems range from simple spa-side push buttons to multiple-function, programmable, low-voltage controls. The most capable ones will enable your clients to operate varying combinations of jets, set system start-up times and temperatures, control the system from a variety of remote locations (and even via telephone) and manipulate a range of associated amenities, including lights, misters and other features.

[ ] Spa covers: Insulated covers on spas offer a set of attractive benefits. Their primary purpose is to prevent heat loss between uses: Any heat that’s retained by the cover reduces the time and cost required to kick the water temperature back up to the desired level. In addition, covers reduce the amount of debris that can fall into the water, which in a small spa can mean the difference between clarity and cloudiness. Finally, lockable spa covers are an effective safety device.

[ ] Bubblers: Not be confused with hydrotherapy jets that entrain air and move it forcefully, bubblers do nothing more than add bubbles to the water for purely aesthetic purposes. Typically, bubblers consist of a channel installed in the floor or seat that feeds air to a series of small holes in the spa’s finish. A few people still claim that these bubbles offer some hydrotherapeutic value, but it’s pretty much agreed that their appeal is primarily visual.

If my clients want bubbles, I’m more than happy to install a system for them. When I do, I also explain to them that there can be some drawbacks to bubblers, particularly when the system is first activated and the air coming out of the bubbler’s channel is considerably cooler than the surrounding water – a problem that can cause discomfort and even minor pain for some bathers.

[ ] Associated waterfeatures: As with swimming pools, this is an area of tremendous expansion in spa design. Basically, any waterfall, cascade or fountain effect you can design into a pool can be applied just as well to a spa. One of my favorites here are large, warm waterfalls that tumble into spas and can be designed with flows sufficient to provide spectacularly vigorous message action for the neck and shoulders.

I also admire designs in which the spa itself takes on the character of a separate waterfeature. You see this effect with perimeter overflow spas, for example. These water-in-transit systems are also praiseworthy from a safety standpoint, because when the water spills over the edge and into a catch basin, all of the system’s suction points can be removed from the spa’s interior.

[ ] Misters: These systems seem to be growing in popularity lately for use with spas. When installed in overhead structures, they add cooling mist to an otherwise warm environment – a function they ably perform whether the spa is in use or not. These are simple, inexpensive systems, and where I’ve used them, my clients really enjoy the contrast they provide for the hot-water experience.

[ ] Fragrances: Some are still dismissive, but aromatherapy has definitely found its way onto the hot-water scene. These days, you can add systems to spas that inject fragrances directly into the water. Although I get uncomfortable with the New Age trappings of all this, I have worked with customers for whom pleasant-smelling water has been a high priority.

In addition to this list, there are other options to be considered, including lighting systems, sound systems and a range of exotic hydrotherapy designs of the sort many of my clients have encountered in resorts and on cruise ships. All of this goes to show just how far-reaching the process of custom-designing a spa can and should be – and how great is the responsibility we all have to know what’s available and how it can be used to the best and most pleasurable effect.

Brian Van Bower runs Aquatic Consultants, a design firm based in Miami, Fla., and is a co-founder of the Genesis 3 Design Group; dedicated to top-of-the-line performance in aquatic design and construction, this organization conducts schools for like-minded pool designers and builders. He can be reached at [email protected].

View Comments (0)

Leave a Reply

Your email address will not be published.

© 2021 WaterShapes. All Rights Reserved. Designed Powered By GrossiWeb

Scroll To Top