by Brian James P.E., Business Development Manager and Roger Weldon, Service Engineer, Grundfos Pumps Corporation Packaged pump systems are gaining in popularity because they include benefits such as space-savings design, simplified installation, single-source responsibility and advanced control options with the ability to communicate with other systems. The term “packaged” means that all the components needed Read more
2016 December – 2017 January
by Brian James P.E., Business Development Manager and Roger Weldon, Service Engineer, Grundfos Pumps Corporation
Packaged pump systems are gaining in popularity because they include benefits such as space-savings design, simplified installation, single-source responsibility and advanced control options with the ability to communicate with other systems.
The term “packaged” means that all the components needed for the pump system are pre-engineered and mounted on a skid or base, making installation simple. In many cases, the installation consists of merely connecting the system up to the suction and discharge piping and providing power to the packaged pump system.
Most manufacturers test the complete package pump system before it leaves the factory to ensure it is ready for installation. These tests include a hydrostatic test to check for possible leaks in the system and a performance or functionality test to determine if the system will operate correctly when installed. This will minimize the common problems associated with built-up pump(s) installations that can not be tested as a complete system until time of commissioning.
VARIABLE FLOW REQUIREMENTS
Domestic water supply systems typically have variable flow demands and can save energy with VFD controlled pump systems. To address these needs, most systems use multiple pumps to meet maximum usage conditions, and use fewer, or even a single pump, to meet minimum usage rates. There is an opportunity for managers of existing pump installations to discover the “true” flow demand and energy consumption of their application by performing a comprehensive pump audit. This information is extremely beneficial because it will determine actual required flow profile and current energy usage during normal operation. Wouldn’t it be nice to have a pump or a pump system that is tailored to a specific application? Acquiring a flow profile for an existing pumping installation provides the precise data required to design/select the optimum pumping system for the application.
New installations typically use plumbing fixture counts and Hunter’s Curves for sizing the pump system as recommended or required by inspectors or local codes. Sizing based on this method can lead to oversized pumps or pump systems. Additionally, this method does not address the variable flow requirement for the domestic water supply.
Determining a flow profile, whether it is an estimate or actual empirical data, will greatly enhance the prospect of designing a pump system that will be the most efficient, resulting in the least cost of ownership.
Figure 1 is a typical domestic water consumption flow profile.
The flow profile in Figure 1 shows the demand increases in the morning and again in the afternoon to the maximum flow of 190 gallons (719 liters) per minute. Then the flow demand gradually drops off until it stops in the night hours. The peak flow is required for only about three hours of the day. The majority of the time the flow is less then 50% of peak flow. A pump system with two pumps would better match the flow profile compared to a single 100% pump. Two 50% pumps with VFD control ensure that the pump system operates near each pump’s peak efficiency the majority of the time compared to a single pump. One 100% pump would run near peak efficiency for less than half of the time. This example shows relatively small flow requirements, but the same variable flow requirements hold true for larger applications, where even more energy can be saved.
VFD-CONTROLLED PUMPS
The Affinity Laws state how the performance of a pump changes with changing pump speed (RPM).
The brake horsepower reduces by a factor of the speed cubed, with speed reduction in the pump. That means small reductions in pump speed can have large reductions in brake horsepower.
Consider a constant speed pump and a PRV to maintain the required pressure (116 ft). The pump builds 167 ft of pressure at the required flow rate where only 116 ft is needed and consumes 5.7 BHP. The extra pressure is reduced by the PRV. This leftover energy is not being used, and is bled off as surplus pressure. The PRV wastes energy and requires periodic maintenance that can be eliminated with the use of VFD-controlled pumps. The difference in brake horsepower between the fixed speed pump and VFD-controlled pump is: 5.71 – 3.77 HP = 1.94 hp
If the reduced operating point was required for 50% of the time and operating 7-days a week; using the cost of energy of $0.10 KWh results in a savings of $750 a year based on an overall motor/VFD efficiency of 85%. This illustrates how a pump with relatively low speed reduction (15% speed reduction) can save significant energy.
The energy savings through use of VFD-controlled pumps is one benefit for system engineers; other considerations are the ability to eliminate PRVs and their inherent energy losses and maintenance costs. VFD-controlled pumps and pump systems allow for precise control of the discharge pressure and have other advantages including:
- Flexibility to electronically “trim” pump(s) when oversized;
- Soft starting of motors so frequent motor starting (motor cycling) is not an issue;
- Smooth and controlled performance ramp up and down; and
- Stop pumps at zero or low flow. Best way to save money when no flow is to turn the pump(s) off.
CHOOSING THE RIGHT PUMP(S)
Pump selection for variable flow applications is a little different than choosing a pump for a single duty point. Variable flow applications are just as the name describes – variable flow. Selecting a pump for a single duty point is more defined, in that the pump selected should meet the duty point at, or very near, the best efficiency point (BEP). Pumps are “happiest” when they run near their BEP. They are the most efficient and have their highest life expectancy when they can run near their BEP. But what about variable flow applications? There is no single duty point for the pump(s), but rather, a range of duty points. Selecting pump(s) for variable flow service is more of an art, in that some considerations must be taken into account:
- NPSH available
- Possibility of the pump system to be oversized or undersized
- What type of pump – single impeller or multiple impeller
When selecting a pump for variable flow service, the duty point used to select the pump value should be to the right of the BEP. The BEP is typically near the center of the pump curve with efficiency dropping as you look to the left and right of the BEP along the pump curve. Selecting a pump to the right of the BEP will allow the pump(s) to operate longer in the best efficiency range with the variable flow demand.
Selecting a pump to the right of the BEP is generally in an area of the pump curve where the pump has an increased NPSH requirement. For this reason not every pump selection for variable flow should be selected to the right of the BEP.
The type of pump is another consideration. Single impeller pumps typically have a flatter curve compared to multiple impeller pumps, and single impeller pumps are less forgiving in situations where conditions change and the pumps are undersized. An oversized pump with VFD control can be electronically “trimmed,” where the maximum speed is reduced to eliminate the possibility of the pump running off its curve. The steeper curve of a multiple impeller pump will allow for a greater opportunity for speed reduction at lower flows and help increase the pump(s) flexibility to meet a changing design pressure requirement. Multistage pumps are more service-friendly than single impeller, end suction pumps. A multistage pump paired together with VFD control, is an ideal choice for variable flow pressure boosting.
PROPORTIONAL PRESSURE CONTROL
Municipal domestic water pump systems tend to have a substantial amount of head requirement dedicated to pipe friction loss. Combine VFD pump control and proportional pressure control (pipe friction loss compensation) and large savings can be realized. Proportional pressure control provides better efficiency throughout the flow range, and can help reduce problems associated with high pressure, which can happen when flow rates are low relative to the design conditions.
Pump systems are typically oversized from the start, and when safety margins are included, most pump systems are larger than what is required. Municipal pump systems with large pipe networks are often purposely oversized to be prepared for future growth. The head requirement for the pump system is calculated by the future high flow design conditions, (i.e., future flow capacity and head at the furthest user or highest pressure drop scenario). Then a pipe friction loss calculation is made using the future growth requirement and the pipe friction head is added to the design condition. This conventional process can result in a large pump system using more energy than necessary.
Let’s look at a four-pump system with a maximum design condition of 2,200 gpm at 115 psi boost or 266 ft. If the design pipe friction loss of the system is 20% of the total required boost pressure (266 ft), using proportional control, the pressure boost at 400 gpm is 212 ft.
Proportional pressure control can decrease the pressure at lower flows and increase it at higher flows where it is needed to compensate for pipe friction loss as shown above.
If the pump system had the lower flow rate duty of 400 gpm for 50% of the time and operated 7-days a week; using the cost of energy of $0.10 KWh, it results in a savings of $2,592 a year based on an overall motor/VFD efficiency of 88%. In addition to energy savings, proportional pressure reduces leaks and saves water at low flow periods by reducing the system pressure.
CONCLUSION
VFD-controlled pump systems offer smooth pressure control with energy savings and the ability to match the flow profile to multiple pumps without waste. Systems with multiple pumps deliver variable flow requirements at an increased efficiency over the entire flow range. This is why it is important to understand the specific flow consumption profile of the installation. For example, if the flow rate is constant, then a single-service duty pump operating at its BEP can be used, and VFD-controlled pumps would not be the most efficient control, but may be desirable for other reasons. VFD-controlled pumps and pump systems may not be the best for all applications, but for variable flow applications such as domestic water pressure boosting, they really do have the ability to save energy and decrease maintenance costs.
CASE IN POINT
The city of Cottonwood, Ariz., nearly doubled its population between 1990 and 2010, which put significant strain on the community’s aging water delivery system.
Residents were faced with frequent water outages that would last a day or two, as well as inconsistent pressure and continual water hammer noises in their homes.
The majority of pumps in the city’s existing distribution system were constant speed, across-the-line pumps that were either off, or running at top speed. The resulting pressure surges subjected the pipes to a 25 psi pressure swing, which stressed and prematurely aged the lines (some dating back to 1930), causing significant leakage and capital repair costs.
The city replaced the old, inefficient pumps with the Grundfos Hydro MPC BoosterpaQ. These integrated pumping systems utilize an advanced controller to adjust pump speed and to stage additional pumps to meet fluctuating system demand.
Overall, eliminating pressure surges in the system has slashed the number of pipe breaks and leaks for Cottonwood by 30% or roughly $38,000 in capital repairs. Moreover, the proportional pressure setting lowers water pressure/volume during off-peak demand cycles, such as overnight, which translates into less wear-and-tear on the community’s pipe infrastructure, as well as less water lost to leaks.
Moreover, the level of “unaccounted water” — which refers to the difference in the amount of water extracted versus the amount of water billed to customers — has dropped to 11% from 40%, helping to bridge the water crisis facing the southwest.
Brian James P.E., is a business development manager and Roger Weldon is service engineer for Grundfos Pumps Corporation. Grundfos is the world’s largest pump manufacturer. For more information, visit www.grundfos.us.
By Mike Agugliaro FORGET THE CARROT AND THE STICK, HAVE A CONVERSATION When your employees show up to work in the morning, are they coming in early, ready-to-work, and motivated to give their very best throughout the day? You may have read that question and laughed at your own answer because you might have to Read more
By Mike Agugliaro
FORGET THE CARROT AND THE STICK, HAVE A CONVERSATION
When your employees show up to work in the morning, are they coming in early, ready-to-work, and motivated to give their very best throughout the day?
You may have read that question and laughed at your own answer because you might have to admit, like many other plumbing companies out there, that employees don’t always engage with their work the way you want them to.
Truth be told, many of your employees might straggle in, need a few minutes to get up to speed, and even then they don’t always deliver at 100% (or even 80%) throughout the day. Many business owners express frustration at how hard it is to find employees who will step up daily and serve your customers at the highest level all day long.
What options do you have to get the best out of them? Most leaders use various motivational methods like the carrot-and-stick method: you tempt them with a reward for good work and you threaten them with punishment for poor work. That’s Standard Operating Procedure for most leaders.
And does it work? Well, sort of. Although all it does is turn you into a Santa Claus with a naughty list and a nice list, offering gifts if only your employees do the job they’ve been hired to do and offering coal if they don’t. You end up having to continue giving them more and more gifts just to get them to do the work you wanted them to do in the first place.
Fortunately, there’s another option that many leaders don’t realize, and this is a powerful option that not only creates inner motivation in your employees, it’s actually more fun (and affordable!) for you. It will create a stronger working environment and more loyalty, too.
Forget the carrot, forget the stick. Have a conversation with each employee. Specifically, learn about them; get to know them; find out about their lives
You see, most leaders think that people show up to work to earn a paycheck. But that is not really the truth. No one really needs a paycheck! The real reason people show up to work is because of what the paycheck can buy. (Re-read that last sentence because there is a lot of truth there!)
Your employees don’t really need money. They need whatever that money buys – food for their family, a roof over their head, etc. Every employee has different reasons for earning their money – some might want to support their growing family; others might have a sick family member they’re supporting financially; maybe they’re sending a child to college; others might have a hobby, like hunting or restoring a car.
When you find out what your employees spend their money on, you find out their deepest “Why” – the reason they get up in the morning, put on your company’s uniform, and show up to work.
Once you know this Why, then you can use it to help them and to help you. Not all employees make the automatic connection between how their work earns a paycheck which allows them to pay for their Why. So you need to help them see the connection.
- Show them that showing up to work on time, and giving their very best, helps them demonstrate their commitment to the job, which creates job security for them, and thus allows them to continue earning money for their Why.
- Show them that serving customers at the highest level, every single day, creates more business for the company, which helps to create more opportunities for them – whether that’s a more job security, an increase in pay, or a higher position in the company.
- There may be times when you need to show them that their poor behavior and unacceptable workmanship doesn’t just jeopardize their job… It jeopardizes their ability to support their Why.
- And, if their work ever changes (i.e. from great to poor) then you have an opportunity to ask them about their Why, to see what’s changed in their lives, and to see if you can help them get back in alignment – either in your company or somewhere else.
The carrot and the stick? They’re useful tools but they just create reactive employees when you rely on just those tools to motivate your employees. The better strategy – the one that is actually more fulfilling for you as a leader – is to get to know your employees and find out what they do when they’re not at work. Discover their Why and you discover the key to creating employees who give their very best always.
Mike Agugliaro is the co-founder of East Brunswick-based home service company, Gold Medal Service. Set as the area’s leading, complete home care business, Gold Medal Service provides residential plumbing, heating, air conditioning, and electrical services all backed by a 100 percent satisfaction guarantee. As an admired business coach, Agugliaro takes from his own experience to regularly lead national speeches, podcasts, webinars, and seminars on behalf of his other business, CEO Warrior, and has published two business books with a third currently in production.
After fielding several calls this week, a contractor noticed a product for sale on Walmart’s web site that’s not a normal product for them to carry. In doing a little research, I found similar competing units for sale on the Sears website and Amazon. the following units for sale on major retailer sites. In each Read more
After fielding several calls this week, a contractor noticed a product for sale on Walmart’s web site that’s not a normal product for them to carry. In doing a little research, I found similar competing units for sale on the Sears website and Amazon. the following units for sale on major retailer sites.
In each case, the products are sold by an independent third party, not the manufacturer or the retailer. How often we get frustrated when the customer can find out what our equipment costs. Does it really matter that a few consumers have this information? Get past that, the equipment cost has no bearing on what the customer actually pays in 85% of the time. What value is placed on labor costs? Most homeowners do not place price as the most important element. They rank a trustworthy company, products that do what was promised, employees that can be trusted, and a company that does what they claimed they would do, all before the cheapest price.
A theme I have preached for years is this: you must become the “Trusted Advisor”. Until the customer likes, believes and trusts you, business is gonna be hard to do. So how do we become the “Trusted Advisor”? Several ways.
Do what you said you would do
If you have an appointment for 9 am, prepare to arrive at least 10 minutes early to your destination in the event of traffic delays.
Don’t pre-judge
Don’t assume what the customer can buy or will buy, keep an open mind. I have been surprised many times by a customer who bought a high end system for an entry level home, and also surprised by a couple living in a 5,000 square home who asked me for a used unit.
Ask questions
When we ask open-ended questions, ones demand more than a yes or no answer, the trust level is improved. It’s similar to your doctor. If you say your arm hurts, and he says “Take these pills once a day”, that’s not the level of service you expected. If you say your arm hurts and he asks “When does it hurt, when did it start hurting, what movements make the pain worse, did you fall, does it hurt when you exercise, when it rains?”, you feel better when the physician asks questions to help him or her diagnose and prescribe the solution.
And while we’re on the subject of trusted advisors, quit selling units, sell solutions. Solutions are how you assemble the products available in the marketplace to meet the needs of your customer.
So how do you respond when someone asks you if you would install a unit they bought online? Make sure your entire company knows how to answer that question. It will come. First of all, let them know you know things the internet sales site does not, until a proper evaluation is done, you can’t be certain that product will even perform to their desired needs. However, let them know with certainty that you are there for them in the unlikely chance something goes wrong or the product will not meet their needs. After all, we have all purchased something on the internet, and found out to our dismay, it was not what we needed, or even wanted. The internet is a breeding ground for scams of all kinds. Some units you see for sale online may be from an insurance claim and have no warranty at all. In fact, they may be sold illegally. Additionally, the consumer is typically responsible for taxes and shipping, and the unit is legally theirs when it is loaded on the truck, so shipping damage becomes the homeowner’s responsibility.
You must have third party stories to share with customers like this one. One of my clients was asked to install a ductless mini-split in a garage the homeowner had bought online. The contractor gave him a price that reflected a typical install and backed out the equipment cost only. After some squawking, the homeowner finally agreed to the install price. When the equipment showed up, it was a model made only for the foreign market. The homeowner had to re-order the correct unit. The information was clear about the product from a contractor’s view on the website, but the homeowner didn’t understand what to look for. So they had to pay for shipping and restocking fees that cost him an additional $1400 by the time he was done. These are the kind of things we see all the time, the homeowner just does not know what to look for, or when they are being scammed.
After the homeowner answers your questions, share your solutions with them. The Internet will not be able to do that. And the reality is that we remember the exceptions, not the average customer. Work with the customers in every way possible to support and help them. However, if a homeowner calls you and asks for a breakdown of your equipment and labor, just tell them no and go on to another one who will trust you. You are not selling them just a product or just the installation labor, your are selling them the whole package that includes the knowledge you may have over your competition that provides tremendous benefit to your customers.