Although heaters have evolved from bulky cylindrical heat exchangers to compact wall-hung units, the concept remains the same, an endless supply of hot water. Tankless actually had its beginnings almost 150 years ago when a painter named Benjamin Waddy Maughn invented the first instantaneous domestic water heater that did not utilize solid fuels. His invention had cold water at the top flowing through wires heated by hot gases from a burner at the bottom. Hot water then flowed into a sink or tub. His invention influenced the work of Edwin Ruud, a Norwegian mechanical engineer and inventor who immigrated to the United States where he designed, sold, and popularized the tankless water heater. He was the founder and president of Ruud Manufacturing Co., now a division of Rheem Manufacturing Co.
As energy efficiency, water conservation, and the green movement in general continue to gain speed, tankless is the wave of the future and contractors who don’t offer tankless may find themselves left behind.
“Tankless adoption in North America is growing at an unprecedented rate,” said Dale Schmitz, marketing manager for commercial, Rinnai America. “At the same time, we are seeing growth slowing somewhat in the very mature tank market. Some of this is due to the law of large numbers, as the overall tankless market share is fractional when compared to tanks. But several factors are fueling this switch to tankless — peer-to-peer sharing and endorsements via social media and YouTube, the explosive growth in food service, hospitality, multifamily, education, and healthcare verticals as well as single family homes — new construction. Rinnai sees these trends intensifying as more companies and households discover that today’s tankless technology is a more dependable, longer-lasting and energy-efficient technology that adds comfort and saves money when closely compared to the alternatives.”
Awareness Builds
“In the ’80s and ’90s, nobody knew about this technology and then about 20 years ago, awareness increased but the understanding and the confidence in what the product could do was still developing,” said Dan Moffroid, director of product management at Bosch Thermotechnology. “What I see now, and even the last several years, that market awareness and acceptance are there.
“The gas tankless market is increasing about 20 percent per year, which is a significant growth,” he said. What we see — more or less — is of every 100 gas heaters sold in the U.S. and Canada, about 15 percent are now tankless and that continues to grow every year. It is an exciting market and quickly evolving to not being a niche anymore, but a regular accepted technology in the marketplace.” Moffroid said.
Efficiencies and Recirculation Technology
“Energy conservation is very important and in some markets regulations are being put into effect to mandate conservation,” Schmitz said. “The tankless water heater category is growing primarily because they are more efficient than standard tank water heaters. Additionally Rinnai offers multiple solutions for recirculation to allow faster hot water delivery to the faucet, resulting in less waiting and less wasted water. Rinnai tankless water heaters can have recirculation set to run on timers or on-demand via push buttons, motions sensors and voice activation.”
“Recirculation is now a common technology in helping the North American consumer have increased comfort,” Moffroid said. “Plus, waiting for hot water to arrive at the sink or the shower is a waste of water, energy and time. Our new unit, the Greentherm 9000, has a pump built into the unit allowing the homeowner to schedule the exact time when they typically need the hot water. The pump is not running when not needed, saving energy.”
The Greentherm 9000 offers a Uniform Energy Factor (UEF) up to 0.96 and innovative features for easy installation, operation and simple maintenance. Models were specifically designed with top connection for water, integrated drain ports so isolation valves are not needed, and a unique integrated sensor technology that auto-calibrates, making the switch to tankless water heating quick and easy.
“One of the biggest misconceptions in the market is the idea all tankless water heaters provide instant hot water,” said Phillip Maxwell, tankless product manager for Rheem Water Heating. “While tankless water heaters will provide a nearly unlimited supply of hot water, it takes hot water the same amount of time to travel from the heater through the pipes and out the faucet as it would with a tank unit.”
“To mediate this misconception, Rheem offers tankless water heaters equipped with built-in recirculation. Auto-learn programming is also available to track water usage over time and auto-program recirculation to meet hot water needs at peak times — so that hot water lines are ready for nearly instant hot water at the faucet, eliminating wait time and wasted water.”
To get hot water instantly, A. O. Smith launched ProLine XE tankless water heaters, which have an integrated recirculation pump with dedicated recirculation lines, saving the contractor time and money during installation. The pump is easily controlled with a simple user interface and multiple pump settings, which allow for customized operation to both meet hot water needs and maximize efficiency. The onboard computer modulates combustion to yield a UEF up to 0.95 while meeting ultra-low NOx gas emissions standards.
- O. Smith also recently debuted the ProLine XE Combination (combi) Boiler for combined domestic hot water and space heating applications. Available in 110,000, 150,000 and 199,000 Btu/hr. models, the ProLine XE Combi Boiler can deliver up to 4.8 gallons of hot water per minute — the highest capacity in the combination boiler category. The product features outstanding energy-saving performance with 95 percent Annual Fuel Utilization Efficiency (AFUE) and a 10:1 turndown ratio. To enhance user comfort, the combi boiler features an air handler interlock that immediately stops non-heated air from circulating when to the boiler is in domestic hot water mode.
Improvements and Advantages
Tankless units also are becoming more efficient with advanced condensing technology designs. “The biggest advantage of a tankless water heater, compared to a tank unit, is the user doesn’t waste money or energy to heat stored water that is not in current need. Tankless water heaters only turn on when in use and do not need to expend the energy to constantly heat water, resulting in lower utility costs,” Maxwell said.
“Tankless designs recently introduced in the market have improved efficiencies, higher gallons per minute output and easier installation — specifically, long vent runs, an easy hanging bracket and a factory wired remote controller resulting in quicker installs. Along with newly expanded Wi-Fi capabilities, those are among the main improvements,” he said.
“Tankless units are ideal for residential and commercial applications that require continuous usage or extended periods of simultaneous demand,” Maxwell said. “Tankless units are also compact and available as outdoor models which can solve space and placement constraints. Additionally, for commercial applications, a multi-unit system provides protection against down time. In the event one unit may go down, there’s no interruption in hot water supply, and business can continue as usual.”
“In residential applications, condensing tankless gas water heaters can save the average family of four nearly $100 a year compared to a standard noncondensing gas storage water heater,” said Arthur Smith, product manager, specialty residential at A.O. Smith. “All of A. O. Smith’s condensing gas tankless water heaters are Energy Star qualified, achieving up to 0.95 Uniform Energy Factors (UEF).
“Another tankless advantage is space savings,” Smith said. “A tank water heater has a bigger footprint: roughly a 24-inch diameter and 50-inch height. In contrast, a tankless water heater is usually about the size of a carry-on suitcase, making it a great fit for a utility closet or confined area. And in warm climates, contractors can install tankless water heaters outside or in an exterior wall to provide even more space savings.”
Rinnai’s latest innovations are focused on making the installation process faster and easier for the installers and to increase connectivity for homeowners and business owners. Rinnai’s Sensei line of condensing water heaters launched this past spring, allows the longest 2-inch vent run in the industry (up to 65 feet), allows for half-inch gas line connections, easy mounting bracket for one person installation. The Sensei is designed to self-compensate in areas with low or fluctuating gas pressures to optimize performance. For serviceability, every component was design to be removed in under 10 minutes, including the heat exchanger, water flow servo, PCB and turbo fan.
Schmitz said there really are no restrictions in terms of what applications can benefit from tankless technology. “Oftentimes we have commercial clients that insist on having a storage tank as part of the overall hot water delivery system. There is no issue with using storage with tankless and in some situations, depending on the applications and demand, it can be advantageous. That is the reason Rinnai began to offer a hybrid water heating option, the Demand Duo, three years ago. It combines a 199,000 Btu tankless water heater with either a 119-gallon or 80-gallon tank and is perfect for emergency replacement or situations that may require ample heated water for high spike draws that happen intermittently throughout the day. In October this year Rinnai added the Demand Duo 2 to its hybrid family of products. As the name implies, it has two tankless units connected to a 119-gallon tank offering 398,000 Btu and built-in redundancy which is important to commercial enterprises like hotels and restaurants.”
Connectivity
Wi-Fi capabilities are certainly the trend among tankless water heaters.
Rheem introduced its EcoNet Smart Monitoring System and smartphone app for users to have available control of their air and water comfort across a wide range of the company’s product portfolio. The EcoNet Smart Monitoring System can alert the homeowner, or their plumber, of service and maintenance needs. In fact, the system offers users peace of mind with leak detection, auto-shut off, and service notifications straight to their smartphone. The EcoNet system is compatible with NEST and WINK smart home systems.
Rinnai’s latest version of the Control-R app allows consumers to control their water heater and its recirculation through Amazon Alexa or Google Home. So, homeowners can now say “Alexa, tell Rinnai I’m going to take a shower,” and the water heater will start circulating hot water to the faucet.
“Connectivity benefits both the homeowner and the serviceperson,” Moffroid said. “The homeowner can control the temperature and adjust or shut down the recirculation system remotely. The homeowner with an app also can see the usage and cost of gas. The water heater will keep track of the Btu its burning and the homeowner can see how many gallons of hot water used in a month, how many Btu of gas and that cost. Some are interested in knowing this, some are not. We’ll see how that information will be used by the homeowner in the future.”
The other benefit of connectivity is from the serviceperson.
“A homeowner can give remote access to the serviceperson who can then connect to that water heater wherever they are and see the history of error codes, burner pressures and air pressures and start to diagnose any potential issues without being at the home,” Moffried said. “Going to the home is time and money for everybody. Now that serviceperson can be more productive and more profitable arriving at the home with whatever part they need and the homeowner can get the problem solved faster.”
Sizing and Scale Buildup
“Perhaps the biggest challenge in any tankless installation is making sure to size the unit properly for the application,” Smith said. “Since the unit is heating water on demand, the contractor needs to size it for the maximum number of showers, sinks and laundry cycles that could be used at the same time. If a contractor sizes for average use, it’s possible that the tankless will not be able to provide sufficient water for all fixtures or at peak demand periods. Tankless water heaters may also be more difficult to install when replacing a tank-type water heater because they generally use different venting and require a larger gas supply.”
Tankless water heaters are also generally more sensitive to water chemistry, specifically hard water conditions.
“Hard water scale buildup can shorten the life of any water heater,” Smith said. Fortunately, there are many methods to reduce build-up. A. O. Smith’s Product Preserver anti-scale filter significantly reduces scale buildup from accumulating in tankless water heaters by promoting the formation of inactive scale crystals that can flow through the water heater without sticking to the heat exchanger. Product Preservers technology is able to filter the water without adding chemicals or requiring electricity. This technology allows contractors to simply replace a cartridge in the filter every two years, compared to competitive anti-scale solutions that require filter replacement every three to six months. Using a water heater and periodically descaling the heater adds extra protection against scale accumulation.
Most manufacturers recommend flushing the heat exchanger once a year to purge any potential built-up scale in the system. Areas with hard water should flush the heat exchanger more often since water hardness is an indicator of scale deposits. “To assist users in unit upkeep, Rheem systems feature a service notification setting that notifies users when maintenance is required,” Maxwell said.
“Tankless water heaters require minimal maintenance, but like any appliance, it is always important to follow the manufacturer’s maintenance recommendations,” Schmitz said. “It is recommended that you flush the Rinnai tankless water heater unit on an annual basis unless the water quality is poor, in which it is recommended more frequently. The process for flushing is relatively simple and can be performed either by the homeowner or by their designated service provider.”
Retrofits Easier Now
“In the past, the install cost of retrofits was high because of perceived changes, sometimes necessary, sometimes not, “Moffreid said. “But the gas infrastructure and sometimes the venting have changed dramatically. Condensing tankless can be installed with PVC or CPVC vent pipe, which brings cost down from when stainless steel vent pipe was needed. And depending on the gas line, it’s sometimes feasible to keep what you have. It also used to require increasing to a three-quarter-inch line. But in many cases the install can be accomplished with a half-inch line, bringing the cost down.”
No Ceiling to How Fast the Tankless Market Will Grow
“Tankless performance, durability and ease of installation have greatly improved over the last couple of decades in the North American market,” Schmitz said. “Moreover, the installers of tankless are better trained, experienced and confident in how to properly sell, install and service tankless water heaters. As more plumbing professionals see the competitive advantage that they hold by offering tankless to customers exclusively or in addition to tanks, there is really no ceiling to how fast the tankless market will grow over the next 5-10 years.”