Three considerations for right-sized tankless installations–and increased customer satisfaction Propane tankless water heaters use less energy, cost less to operate, and produce fewer emissions than other options, which is why a growing number of homeowners are requesting these systems. As contractors know, determining the right configuration for their projects isn’t always straightforward. Whether considering a Read more
tankless water heaters
Three considerations for right-sized tankless installations–and increased customer satisfaction
Propane tankless water heaters use less energy, cost less to operate, and produce fewer emissions than other options, which is why a growing number of homeowners are requesting these systems.
As contractors know, determining the right configuration for their projects isn’t always straightforward. Whether considering a single unit for the whole home or multiples that run in tandem, knowing how to predict demand is key to giving customers a setup that meets their performance and cost expectations.
Here are three factors to consider when right-sizing a tankless system for projects.
How much water will the customer need?
Knowing how many people will live in the home, who will be using hot water, and for what purposes is the first step toward installing a system that will fulfill their specific needs. Additionally, understanding a customer’s lifestyle and habits–when they shower, how often they do laundry, and whether they expect to install radiant heating–can help determine expected peak demand times.
Take stock of the number and type of appliances and systems requiring hot water and note their water delivery rates. To calculate peak demand, the Department of Energy (DOE) recommends counting the number and gallons per minute (GPM) rate of faucets, showers, and appliances that could be in use in the home at any given time. Features such as in-floor radiant heating and spas can considerably raise a home’s hot water demands. Propane tankless water heaters provide an endless supply of hot water, averaging roughly 222 gallons per hour, compared with an average first-hour delivery rating of just 62 gallons per hour for electric storage tank models.
How much will the water need to be heated?
It’s important for contractors and installers to know the difference between outdoor ground temperatures and the desired indoor hot water temperature. That will reveal how much the water will need to heat and, therefore, how quickly the unit can deliver hot water.
For example, a typical shower head delivers 2.5 GPM, so a 9.4 GPM unit would run three to four showers depending on the inlet ground water temperature. According to the DOE, the average groundwater temperature across the U.S. is 50 degrees. In most cases, water should be heated to at least 120 degrees, so the home will need a tankless unit that can heat 2.5 GPM by 70 degrees. Lower flows can be heated to a bigger temperature rise and higher flows to a smaller temperature rise. Most propane or natural gas tankless water heaters on the market can handle a rate of 5 GPM at a 70-degree temperature rise. As fixtures are added, demand on the system increases and that 5 GPM rating can quickly get overwhelmed.
While a tankless unit will provide hot water almost instantly at the unit, the water still has to travel to the faucet, so location of the units is an important part of system design. Oftentimes, two smaller units, each placed closer to the end use site, can provide the project a higher level of satisfaction than one large or two smaller units installed in a single location. This also provides some redundancy if a unit or fixture needs to be serviced.
What can the home accommodate?
Peak demand scenarios are why contractors shouldn’t assume an undersized system will cover their client’s full range of needs. Oversizing isn’t as big of a concern with tankless systems. While oversizing a traditional tank water heater would result in significant wasted energy over the life of the unit, tankless units vary their flow rates based on demand and, therefore, having excess capacity doesn’t necessarily mean a tankless system is using more energy.
New projects can more easily accommodate tankless units at the point of use than existing homes, which are often designed for a central tank system–and may be better suited for one or more units installed in the basement. For most projects, one unit is sufficient. Multiple units may be used to handle larger loads or as homeowners scale up in the future as their hot water needs change. Because of the popularity and dependability of propane tankless water heaters, new products are available on the market that would allow customers to have “multiple” heaters in a single cabinet, or on a single rack that comes to the project ready for installation making system design easier still.
To determine the optimal number of tankless units for a home, help customers understand their consumption habits and how the system can be sized to meet their expectations. Determine peak demand and gauge actual usage and lifestyle habits. Then, compare prices for systems that meet those needs relative to a client’s budget. Put in as much capacity as those factors will allow to balance cost and comfort. By simply installing a propane system, customers will see optimal cost savings. That’s because propane tankless water heaters offer reduced energy costs, a lower total cost of ownership, and a longer service life compared with other options. Notably, propane tankless systems can reduce energy costs by up to 50 percent and eliminate standby energy loss from the tank.
To learn more about propane water heating systems, visit Propane.com/Water-Heating.
Bryan Cordill the director of residential and commercial business development for the Propane Education & Research Council. He can be reached at bryan.cordill@propane.com.
The Plastics Pipe Institute, Inc. (PPI), has published a new recommendation related to the direct connection of plastic piping materials CPVC, PE-RT, PEX, and PP to tankless water heaters. Available on PPI’s website, PPI Recommendation H Direct Connection of Plastic Piping Materials to Tankless Water Heaters for Domestic (i.e. residential) Applications provides clear guidance on Read more
The Plastics Pipe Institute, Inc. (PPI), has published a new recommendation related to the direct connection of plastic piping materials CPVC, PE-RT, PEX, and PP to tankless water heaters.
Available on PPI’s website, PPI Recommendation H Direct Connection of Plastic Piping Materials to Tankless Water Heaters for Domestic (i.e. residential) Applications provides clear guidance on the question of direct connection of these piping materials to tankless water heaters. PPI is the major trade association representing the plastic pipe industry.
“PPI Recommendation H answers questions which plumbers and builders have been asking about whether it is appropriate for plastic pressure pipe materials to connect directly to the cold-water inlet and hot-water outlet of domestic tankless water heaters, without the use of metallic flex connectors. Based on our research, these direct connections are usually acceptable,” explained Lance MacNevin, P. Eng., director of engineering for PPI’s Building & Construction Division.
“To help answer this question, PPI and our members researched Canadian and US model plumbing codes,” he continued, “reviewed the published literature on dozens of tankless water heaters, and confirmed the recommendations of plastic piping system manufacturers. Based on the proven high-temperature capabilities of these piping materials and the relatively consistent water temperature control of modern tankless water heaters, there is no technical reason to prohibit direct connections. Of course, installers must follow local code requirements and the manufacturer installation instructions.”
“As stated in Recommendation H: Piping systems using the materials CPVC, PE-RT, PEX, and PP, which carry a pressure rating of 100 psi at 180°F (690 kPa @ 82°C), and which are intended and certified for hot and cold potable water distribution systems according to industry standards and relevant codes, may be connected directly to tankless water heaters which are intended for domestic (i.e. residential) applications, unless prohibited by local plumbing code or the specific water heater manufacturer.”
According to PPI President David Fink, “The research on this topic was prompted by an inquiry from a major builders group. The rapid development of Recommendation H demonstrates the ability of PPI members to collaborate and respond quickly to industry questions about responsible usage of plastic piping materials.”
Published on PPI’s website directly at recommendation-h-direct-connection-tankless, Recommendation H is one of several PPI documents related to the design and installation of pressure pipe materials for plumbing and mechanical applications, which are all published as a service to the industry. Additional information about PPI’s Building & Construction Division can be found at plasticpipe.org/building-construction/index.html.
With an enrollment of more than 27,000 students, the University of New Mexico is the state’s largest college. It’s known for its strong and historied athletic programs, particularly the Lobos football and basketball teams, which compete in the Mountain West Conference. Dreamstyle Stadium has been home to the Lobos football team for 60 seasons. The Read more
With an enrollment of more than 27,000 students, the University of New Mexico is the state’s largest college. It’s known for its strong and historied athletic programs, particularly the Lobos football and basketball teams, which compete in the Mountain West Conference.
Dreamstyle Stadium has been home to the Lobos football team for 60 seasons. The 39,224 seat football stadium is attached to the L.F. Tow Diehm Athletic Facility. Tow Diehm, who’s known as the “Father of Athletic Training” in New Mexico, served as UNM’s athletics trainer for 31 years.
Inside, the facility includes athletic offices, common areas, locker rooms for both home and visiting teams, and a weight room that underwent an $800,000 renovation in 2014.
A more recent renovation took place in the facility’s primary mechanical room. Over the past few years, the domestic hot water system began failing. Nonstop pump failures, electrical problems, and a leaking hot water storage tank plagued maintenance crews.
These problems inevitably surfaced at the worst times, like game day. The system provides hot water to all fixtures within the building, including the home and visitor locker room showers.
“We were frequently called in after hours to tend to the old system,” explained Richard Van Damme, HVAC master for the University of New Mexico. “At one point, we had even drained the 1,600 gallon storage tank for replacement, only to fill it again a few days later for game.”
Hot water was being supplied by two large, atmospheric volume water heaters with capacities of 490,000 BTUH each. The maintenance department had been pushing for replacement for a number of years. The cost of maintenance was rising, outright failure was imminent, the system’s dependability was lacking and efficiency was a concern.
“When we received a work order to replace the failing system, we evaluated a straight, in-kind replacement with standard efficiency water heaters. Installing a similar storage tank would’ve required removing part of the roof. We also looked at tankless style system options. Energy savings was a big consideration, as was redundancy and serviceability,” said Jesse Hart, facilities engineer for UNM’s facilities management department.”
“There are short periods of high demand, with low or no demand otherwise,” he continued. “The showers aren’t even used year-round, so the application lent itself perfectly to a hi-efficiency, low-volume hot water system. Standby heat loss from the big tank was significant.”
UNM looked at various tankless products and contacted their local Navien representative, Jordan Mahboub, at RepNet. Mahboub and Hart worked closely with Navien sales engineers to create a design based on the peak hot water demand at the L.F. Tow Diehm Athletic Facility: 82 gallons per minute at 120F. The university wanted the ability to meet peak demand with one or two units offline.
Once the design was approved, Futures Mechanical was hired for the replacement. The volume water heaters and storage tank were removed and 18 Navien NPE-240S condensing, tankless water heaters were installed.
The NPE-240S is a 199,900 BTUH condensing, wall-hung water heater that features dual stainless steel heat exchangers, a 10-to-1 turndown ratio, and efficiencies up to 97 percent. The unit also provides LEED points, where applicable.
Water heaters were installed in two independent systems, one on either side of the mechanical room to serve each locker room. Navien’s Ready-Link manifold system was used to simplify the installation and save space.
The Ready-Link Manifold System provides everything required for a multi-unit installation, including manifolds for water and gas, racks for floor mounting, valves, connections and flex lines.
Up to 16 NPE-240 units can be common vented, so only four roof penetrations were needed at the athletic facility.
“No intricate programming was needed to cascade this many units in a single system,” said Van Damme. “By using the factory-supplied cascade cable, the logic built into the units does all the thinking. If for some reason the master unit goes down, the next unit in line takes over, so there’s no downtime in the event of a unit failure.”
“Having Jordan Mahboub here during commissioning helped us learn all the advantages of the Navien system,” Van Damme continued. For example, each rack requires a single gas regulator, not every unit. The manifold system lets us isolate any unit in the group for service without taking the others off-line.”
When the new system was tested, every hot water fixture in the facility was opened for almost two hours. The units cascaded to meet demand, but never fired to 100%. According to Van Damme, full capacity was met and sustained while the systems are operating at 60% input.
“The modulating component was a feature we really wanted,” Hart said. “Each of these units provides a 10-to-1 turndown, so no matter if there’s one sink or 20 showers running, we can accurately match the load. We’re not using energy beyond what’s needed to meet the actual demand. Now that the system has been operational for over a year, we’ve found an annual natural gas savings of 2,282 Therms.”
The entire project took three months over the 2018 summer break. The installation was seamless, and was completed just in time for football season. There’s now more space to service the water heaters or work on other equipment within the room.
“I think this system is a great asset to the stadium,” Van Damme said. “The money saved on maintenance alone is significant. We’ve been so impressed with these units that we’ve decided to use Navien systems in other locations across campus.”
Irvine, CA – Navien has added to their website, NavienInc.com, the ability to view the website in Spanish. In an effort to make more information available to Spanish speaking visitors, Navien has gone through a grand project of translating the entire NavienInc.com website along with brochures, manuals, guides and more. Visitors can now search for installers in Read more
Irvine, CA – Navien has added to their website, NavienInc.com, the ability to view the website in Spanish. In an effort to make more information available to Spanish speaking visitors, Navien has gone through a grand project of translating the entire NavienInc.com website along with brochures, manuals, guides and more. Visitors can now search for installers in their area, register a Navien product, learn about Navien tankless water heaters, combi-boilers or boilers and much more on the website in either English or Spanish. To access the Navien website in Spanish, click on language within the main navigation at the top of the website and select, or directly visit the website in Spanish by going to NavienInc.com/es.
Washington — The Propane Education & Research Council released a video for commercial builders and contractors that provides a comprehensive overview of tankless water heaters. The video details how the systems work, their role in meeting LEED certification, and more. https://youtu.be/A24yGp-dUek “Many commercial building owners and operators are finding tankless water heaters to be a valuable Read more
Washington — The Propane Education & Research Council released a video for commercial builders and contractors that provides a comprehensive overview of tankless water heaters. The video details how the systems work, their role in meeting LEED certification, and more.
“Many commercial building owners and operators are finding tankless water heaters to be a valuable investment — whether in retrofits or new construction projects,” said Bryan Cordill, director of residential and commercial business development at PERC. “These systems are bringing significant space and energy savings to businesses across the country, especially as tankless technology continues to evolve. This video helps showcase how propane tankless systems can be a solution for a wide variety of commercial building types.”
The video outlines the importance of maximizing space and efficiency in commercial buildings, given that water heating is a major energy consumer in many buildings — particularly older buildings in need of renovations. In fact, nearly 80 percent of water heating energy use occurs in buildings built before the year 2000.
Current water heating technology, especially propane tankless systems, can offer big improvements in terms of performance, energy use, and energy costs. Plus, they’re versatile, so tankless technology for commercial buildings can meet a wide range of load types. As outlined in the video, individual tankless units can be combined into larger configurations, allowing them to provide hot water rates of several hundred gallons per minute — and ultimately, the ability to handle water heating no matter the size or scope of a building.
Visit Propane.com/Commercial-Buildings to learn more about the advantages of going tankless in commercial buildings.