Over the past several years, the aquatic industry has become more innovative, introducing owners and operators to new technologies and advancements which ultimately create opportunities to improve safety, increase longevity of the facility, and even provide energy savings. One of the advancements the aquatic industry has been very enthusiastic about is Variable Frequency Drives (VFD's).
WHAT IS A VFD?
A VFD is essentially a power conversion device. VFD's convert basic fixed-frequency and line power to a variable frequency and variable-voltage output which is used to control the speed of induction motors or pumps. Most VFD's are simple to install and are user friendly, however they are quite sophisticated in relation to their hardware and software operation.
The basic function of a VFD in the aquatic industry is to provide substantial energy savings. This is accomplished by controlling the speed of a pump rather than controlling flow through use of a throttling valve. Essentially, when you reduce the speed of a pump, you create energy savings. In addition to energy savings, the life of the impeller, bearing and seal is greatly improved which leads to longer lasting pumps.
BENEFITS OF USING A VFD
Saves money on energy consumption.
Maintenance costs are lower due to the lower operating speeds resulting in a longer life for bearings and motors.
A soft starter for the motor is no longer required.
Controlled ramp-up speed in a pool system can eliminate water hammer problems.
With a compact and modular design, VFD’s do not take up a lot of space.
Protect against system overloads, motor failures, motor and drive overheating, voltage disturbances, power surges, loss of phase, ground fault, overvoltage, over current, under voltage, external fault, over temperature, etc.
Minimize motor noise and heating with adjustable switching frequency modulation.
WHAT CAN'T A VFD DO?
Boost the output voltage significantly above the input voltage.
Increase the output power of the pump or motor.
Fix mechanical problems.
Variable Frequency Drives are a great addition to any pool equipment room whether it’s new or existing. Not only do they save owners and pool operators on the costs associated with high energy consumption, but they also increase the longevity of the pumps and motors. VFD’s are available in different sizes (HP) and voltage requirements.
In today's world swimming pools are all around us. Who doesn’t have a pool in their backyard or have a close neighbour with one? Friends and family gather around them, making wonderful memories every day. Fitness clubs have pools, community centres have pools, hotels have pools, and now high rises in the sky even have them. Building a residential or commercial pool on the ground level is a relatively easy task, but what are the challenges of building an elevated pool high in the sky?
When building in a high rise structure, several considerations need to be taken into account during design. Keep in mind a 4 foot deep lap pool that is 75 feet long holds approximately 75,000 gallons of water. Water weighs 8.34 pounds per US gallon, equating to 625,500 pounds of water - and that’s just the weight of the water! Add in the weight of the concrete pool shell, reinforcing steel, interior finishes and mechanical items and it doesn’t take long for a small lap pool to weigh in excess of 900,000 pounds. That’s a lot of additional weight on a building structure or roof top. Structural engineers and architects have their work cut out for them to design and engineer a building structure that’s safe enough to hold all of this additional weight.
One other consideration when designing a swimming pool in an elevated structure is waterproofing and sealing of the structure. Nobody wants 75,000 gallons of water leaking out into a building and running down into the main lobby. Today’s swimming pools have cantilevered edges that hang out over the edge of buildings, windows in the walls, and in some cases glass bottoms. Providing a positive seal in extreme building conditions such as this can be a challenge. Engineers spend countless hours running calculations to provide 100% watertight designs.
Aside from the structural and waterproofing challenges outlined above during design, now there is the challenge of building it. Countless men and women climb story after story of stairs or ride construction elevators 10, 20, even 50 stories up to start construction of these wonderful and challenging pools high in the sky. Hundreds of cubic meters of concrete need to be pumped up, or craned up sometimes hundreds of feet to be poured in place. Thousands of pounds of structural reinforcing steel and mechanical equipment need to be hoisted in place by tower cranes and snaked through the building structure to be constructed in place. Every move in this elevated construction environment needs to have several hours or even days of planning. On the ground it's easy, back up the cement truck and start pouring. When you're 50 stories in the air, it’s a little more challenging.
So the next time you visit a luxury hotel or you're at a resort on your next vacation check out the roof top swimming pool. Challenge yourself to swim out over the cantilevered edge and imagine the challenges of constructing that beautiful masterpiece.
Fun Fact: Some elevated swimming pools in high rise buildings are used to protect the building structure in event of a fire. Some of these pools have a connection so the fire department can quickly pump water out of the pool in the event of a building fire.
Cast-In-Place Concrete Vs. Shotcrete: What's The Difference?
Wednesday, March 13, 2019
Today, the pool shell of a commercial swimming pool can be constructed in several ways. Two of the most commonly used methods are cast in place concrete and shotcrete. The major difference between the two is quite simply the method of placement. At the end of the day, both systems, with proper design and construction, will provide a rock solid pool shell which can last for more than 40 years.
Cast in place concrete construction can be a costly and very labour intensive process. This type of construction requires additional excavation to allow workers room to install an extensive forming system for both the inside and outside of the pool walls, which is used to contain the concrete and shape the pool structure. This working room behind the forming system requires backfilling when the concrete work is complete.
Once the formwork is in place, concrete is discharged from a ready-mix truck, and transferred to the work area by way of boom pump, line pump, buggy, or down the chute directly off the back of the truck. Next, concrete is placed on the ground or in the form work, and then must be vibrated for consolidation & compaction.
Cast in place concrete forming system.
Pouring cast in place concrete.
It’s the most common type of concrete construction.
Cast-in-place concrete will result in a strong and waterproof structure with compressive strengths of 4,000 to 5,000 psi.
When properly designed and constructed, cast in place concrete results in a relatively smooth surface that will require very little surface preparation for the use of epoxy-based pool paint, tile and plaster finishes.
Cast-in-place concrete results in the most uniform surfaces possible.
Over excavation is required to allow working area behind the forming system.
Very labour intensive to form the walls.
Backfilling of the formed walls is required.
It’s harder and much more complicated to form shapes.
Generally more expensive to construct in comparison to a shotcrete pool.
The quality of a shotcrete pool can be comparable to a cast in place pool with one exception. Typically, they do not require extensive forming which often results in cost and time savings. Although the hardened properties of shotcrete are similar to conventional cast-in-place concrete, the nature of the placement process provides additional benefits, such as very fast erection, particularly on complex forms and shapes, including curved walls. Due to the speed of construction and the minimal equipment requirements, shotcrete is a very cost effective building method.
The shotcrete method utilizes concrete that is discharged from a ready-mix truck into a shotcrete pump and then pneumatically “shot” in place against a wood or earth form. To increase the velocity of the material which improves the control of the “shooting” process, accelerators and other admixtures can be added to the nozzle along with air under pressure. Because shotcrete is "shot" up against wood forms or earth, there is generally very little backfilling required.
Pool form ready for shotcrete.
Shotcrete being "shot" into place.
No over excavation required. As a result there is very little to no backfilling required.
The ability to build in very tight spaces and “free form” applications make it very simple to build pools of any shape.
Higher compressive strengths than cast-in-place concrete. Typical compressive strengths of shotcrete are in the 6,000 to 7,500 psi range
Lower construction costs.
There are fewer trained and skilled in the use of shotcrete than that of cast-in-place concrete.
The finished surface of shotcrete is rougher than a finished surface of a cast-in-place concrete pool. Additional surface preparation is required before the application of epoxy paint. As a result most shotcrete pools have a plaster finish.
There are a lot of considerations when selecting a swimming pool contractor to build your pool. Whether the project is a high-end residential project or a multimillion dollar waterpark, it is important to be very diligent in selecting the builder to avoid delays, cost overruns, improper construction and lots of headaches. But what things should be considered?
WHAT DOES THEIR SAFETY RECORD LOOK LIKE?
The safety record of a company should be a primary consideration. A company with a poor safety record attracts a lot of attention (not the kind they want) and can really bog down a project. In fact, a project can be put on hold for an extended period if there are glaring safety infractions or heaven forbid a serious injury or fatality on the job site. Ask the proponent for a copy of their Health and Safety Policy, and safety record. If they don’t have one, or are unwilling to provide information, move on.
PRICE ISN'T EVERYTHING
Price, while always an important consideration is not everything. We frequently hear our clients say “…I wish we had gone with the more reputable builder. This job has become a nightmare…” The saying “you get what you pay for” could not be truer. If the price seems too good to be true, it is. There is no such thing as an extraordinary $7 bottle of wine, and there is no such thing as an inexpensive Bugatti car. The two things are mutually exclusive. The Bugatti and a K-car will both take you to the store, but the Bugatti will take you to the store for decades (and look really good doing it!), and there is no comparing the quality of the two. The same is true in pools. You can choose a method and a builder that may appear to save you a little coin but suffer endless change orders and additions to the project. Or you can spend that little extra bit of money to hire a thorough and reputable builder and have peace of mind for years to come.
DO THEY HAVE A STRONG FOUNDATION?
Like a strong building, a strong company needs a strong foundation. In the construction business, this foundation is in the form of knowledge that is both deep and wide, and can only be acquired from years of experience specific to the industry. A newer business just doesn’t have the history to be as knowledgeable as a well-established company that has been around for a long time. In the experienced company, there are senior people and younger members of the team. There is a combination of high energy and drive and a deep well of information that was developed over decades of practice. The thing about knowledge is that it is often applicable to a wide variety of applications that help experienced builders provide the best outcome for the client. Hydraulic concepts in pools and water management for example, are often applicable to electricity where Voltage equates to Feet of Head and current flow to velocity. Companies who have a deeper knowledge in their art have a broader understanding of the many things they may encounter in performing their work. Look for contractors who have a broad range of experience over a long period of time, senior people who have “been around the block” a couple of times and young energetic and well educated project people.
DO THEY HAVE INTERNAL SYSTEMS IN PLACE?
It is a great thing to have knowledge, but if it is held by a few individuals it often fails to crystalize in the positive outcome of your project. Good companies develop internal systems that reflect the Best Practices that have been developed out of the knowledge gained from experience. It is these companies who seek to establish a culture of quality and caring expressed in writing the form of standard operating procedures. Ask your potential contractor if they have internal systems in place to support quality assurance, delivery, and value added designs, longevity of the product, and so on. A company with systems is a company that cares about what they do, and who they do it for. Also ask if the company has a Mission Statement. The Mission Statement is the guiding philosophy of the company. A company without a mission is like a pilot without a map. Yes, the plane is flying…but the destination is dicey.
WHAT IS THEIR EXPERIENCE LEVEL?
The Record of Experience speaks volumes about the knowledge base of the company. Obviously, the more pools a company has built, the more experience they have. But it is also important to look at the different types of pools that a company has built. Not all pool builders build all pools, and sometimes for good reason. For example, Company ABC may be an advocate for cast-in-place pools through their limited knowledge and experience; they know how to build them, but nothing else. Concrete pools are really good and are considered the gold standard in the industry, however, there are times when another type of pool is more appropriate than a concrete pool. If the pool is going on the top floor of a high rise, weight may be a limiting parameter. It is important to find a builder who has the experience to recognize and understand your options and what best suits your needs. Ask your potential builders for their list of projects (current and complete) and also for a list of references. If the record of experience is small or limited in scope, you may want to look a little deeper into the company. If the reference list seems small compared to the record of experience, it should raise a red flag! A good contractor doesn’t maintain a specific reference list…every single client should be a reference.
DO THEY USE THEIR OWN FORCES?
If the builder you are looking at using has a lot of subcontractors, it may be worth looking a little further. Dividing the scope into different trade subcontracts (mechanical subs, waterproofing, tile, concrete etc.) dilutes and displaces responsibility of the trades and of the general contractor. When something goes wrong, it’s nobody’s fault, and it’s everyone’s fault. A great deal of time is spent trying to figure out if the waterproofing contractor caused the leak, or if the tile contractor damaged the waterproofing. Or maybe the concrete contractor is at fault. It is best to source a contractor who self-performs the entire pool scope with their own forces from the excavation, to mechanical and electrical work, to tile setting and commissioning and training. When there is only one company performing the entire scope for the work, there is no opportunity to cast blame for problems to others. You only have one phone call to make.
ARE THEY FINANCIALLY STABLE?
The financial stability of the company is also an important consideration. Are they able to completely bond a large project? Often tender documents ensure that this is the case, but private projects may overlook the need. What happens if things go wrong, or the contractor walks off the job or goes bankrupt? Who will finish the job? Who will pay for the work? Also, you want to be sure that the company you select is going to be around tomorrow and for years to come. Of course, there is never a guaranty but the best predictor of the future, is a record of the past. If the company has been building great pools for decades, they are likely to be around for a long time to come.
DO THEY HAVE A SERVICE DEPARTMENT?
Once the pool is built, you are away to the races. But what if something goes wrong with the pool after a few years? Who will close the pool for winter? It is always best of the company you choose to build the pool also has a service department who can deal with any problems and to perform regular maintenance. The service department of the company who built the pool is best equipped to service the pool since they will have an intimate knowledge of the pool from the construction phase. There are many “pool builders” out there who actually have no idea how to best operate a pool, and have no service department. It is best to steer clear of these builders. Once the project is complete, you never see them again.
CAN THEY PERFORM?
Finally, schedule can be critical, especially for commercial projects. Liquidated damages can cripple a business that was counting on opening the pool in December, but it didn’t happen until the following May. There has been more than a few projects abandoned or sold for pennies on the dollar as poor performing contractors drove the owner into insolvency. No builder is perfect or immune to making mistakes…things happen. What sets the premium builder apart from others is how they react to the problems. The only way to know how different builders react is to speak with their past clients. Don’t accept a short list of “preferred references”. It is a lot of work to fully research your builder, but it will pay dividends many times over in the long run.
A well-constructed pool delivered on time and on budget will provide decades of enjoyment, or in the case of a commercial project, revenue generation. The best start to this positive outcome is to balance all of these considerations discussed, and make a good decision.
Following construction, the commissioning of the pool system is critical to ensure that it is working properly and as it was designed, before handing over the operation of the pool to its Owner. These are the people who will be operating and maintaining their body of water on a daily basis.
During commissioning, all pieces of equipment are started-up, run, and programmed. I have learned first-hand how important it is to allow for the proper amount of time for this to occur. Allowing a few weeks to complete the commissioning ensures that each piece of equipment has enough time to operate as designed. If anything goes wrong it can be rectified immediately.
The set-up of the system begins when the water is introduced into the pool. Once the water starts to run through the piping, it is also running through each piece of equipment that is required to operate the system. Here are a few examples of equipment that requires set up;
The chemical controller, which monitors and reads the pools chemistry, requires some initial set up. The controllers parameters are set to ensure that if the chemistry is not within those parameters, the controller alarms to alert the operator that the water chemistry requires attention. This can take time to complete to ensure accuracy.
After the pump is started up, it should be allowed to run for a period of time to ensure that there are no leaks. Seals in a pump can be dry and cracked before the pump is even installed. You won’t be able to physically see this issue until the water is running through the system.
Those are just two examples of the numerous pieces of equipment that are involved in pool systems, most of which require set up. There is always a possibility that equipment can fail, so ensuring everything is commissioned by the time the system is fully operational means less chance of equipment or system failure. When there is a failure after the pool is fully operational, it could mean that the pool would have to be shut down and closed to its patrons. This is something that all Owners want to avoid at all costs.
Once the pool is completely commissioned, it is now the perfect time to train those individuals who will be operating the pool on a daily basis. Every pool system is different, so even if a person has experience with pool systems, the new system could be slightly different. A controller could be updated from the previous version, or the system could include a UV system that the Operator has no previous experience with.
Training sessions cover many techniques including:
How the piping system flows
How to operate the controller
Understanding what can go wrong
What to do if the pool overflows
How to adjust chemistry of the pool
What to do if the system equipment is in alarm
Allowing those people the opportunity to watch and learn through a hands-on training session has amazing benefits for them in the future operation of the pool. When Operators have the understanding and knowledge that they need, their confidence level is increased, allowing them to maintain the system properly, and promptly deal with any issues that may arise, shortening their down time.
As you can see, commissioning and training benefits all parties involved in the operation of the pool system. The time for this to occur should be considered in every construction schedule.
Health inspections are actually my favorite part of my job. Not only because the project is nearing completion, but for the sense of accomplishment when the Health Inspector comes to the facility, inspects all code requirements, and provides us with a “PASS” to open to the facility to the public.
Having years of experience in construction and participating in hundreds of health Inspections, I hear a lot of the, “Why do they have all these rules?”, “We will never be able to satisfy them”. My response to these comments is simple; Let’s do what the regulations asks for and we will get the outcome we want. It does help that we have been through lots of these inspections and can be prepared for them, but just being aware of the code requirements gives anyone the ability to be successful.
Here are a few common and very important items that the Health Inspector will look for when they inspect any facility. This is just a portion of the requirements that are listed in Regulation 565 of the Health Protection and Promotions Act for Ontario.
Do you have an emergency telephone installed and in working order? Are there instructions for your staff or patrons for when an emergency call is made? If any emergency occurs within the pool area and 911 needs to be called, anyone in the pool area may pick up the emergency phone to make the call. When making that call, the 911 operator will ask questions that will need to be answered promptly. Having the emergency instructions with the facility information posted is required so that person is able to relay this information to the 911 operator.
Are all the required safety signs posted? The regulated safety signs are to ensure that your patrons know the rules of the pool, where the emergency phone is and remind them to shower before entering the pool. They also identify for the staff how many bathers can be in the pool at one time. The signs have to legible and posted at all times.
Is the required safety equipment accessible for the patrons and staff in the pool? The health regulation lists the required safety equipment that you need on hand in case of any emergencies. These items should be maintained and checked to ensure they are in working order on a regular basis. You would never want to be in an emergency situation without the proper gear.
POOL CHEMISTRY LOGS
Are your pool chemistry logs up-to-date? Is your pool chemistry within the proper parameters? Recording your pool chemistry every 2 hours can feel exhausting especially if you don’t have a machine to handle those recordings for you. It is something that the Health Inspector will expect to see being completed. The inspector will also look for the daily and monthly checks that are required for the main drain covers and GFCI’s. Always have these records accessible. Pool chemistry can change very quickly and cause your pool to be unbalanced. Unbalanced chemistry in your pool can cause harmful bacteria and infections, and needs to be adjusted as soon as the readings are taken. Ensuring you have a test kit and a stock of chemicals on hand at all times. If the chemistry needs to be adjusted it can be done promptly.
A Health Inspector is not only ensuring that your pool complies with the rules that have been set out by this governing body, but they also ensure that the Owner and the Operator of the pool understand the codes and will follow them during operation of the pool. While the pool is in operation the patrons that are using these swimming pools do so with confidence that the individuals running those facilities are complying with the municipal codes and understand how to do so. The Health Department along with the Health Regulations will ensure this. For the Owners safety as well as the patrons.