The Tankless Phenomenon

BY JOHN MESENBRINK,

chief editor

So is tankless the next logical step to the water heating part of your business? You might answer that based upon the amount of water the applications needs, or perhaps your geographical location. But tankless water heaters have made technological strides in that they are not considered for summer cottages only any more, and the market is now poised for installation in everyday retrofits and new construction.

Tankless has much more far-reaching market saturation -- more than the dreadful shadow of the slow residential construction monster can cast. Nevertheless, tankless manufacturers are adamant about the success and survivability of tankless water heaters through retrofits, remodels and the green, energy efficient movement. Although residential construction has come to an excruciatingly patience-testing slowdown, for some tankless manufacturers, every cloud has a silver lining. “The slowdown period in residential construction has generated competition among homebuilders to install high quality products,” says Jerry Pan, Nortiz America. “Currently, the overall tankless market consists of about 6% of the total water heating demand in the United States. There’s a tremendous amount of room for growth,” adds Pan.

And retrofitting is where its at. “Presently the majority of sales are with retrofits because people are informing themselves about tankless technology, recognizing the benefits and getting rid of the bulky and limited tank-style water heaters. The Internet as a tankless research tool has helped greatly, allowing homeowners and contractors alike easy access to a lot of information. They can easily cross-reference and compare several different units and suppliers,” says Bill Riley, sales and marketing specialist, Stiebel Eltron.

By now, I’m sure that you have heard of at least some of the benefits of tankless water heaters. Benefits include:

•  Unlimited supply of hot water -- the Stiebel Eltron tankless, electric hot water heaters, for example, provide a continuous supply of hot water -- on demand -- only the amount you require, when you require it, for as long as you need. “There will be no more waiting for the tank water to reheat once depleted. Peace within the family is maintained,” says Riley.
• Ease of use -- Simply set the temperature of the water you want on the front dial. Several sensors and a microprocessor ensure that the temperature of the water does not deviate from the set-point dial selection.
• Energy saving -- In comparison to electric tank style heaters the homeowner will save 15-20% on the water heating portion of their electric bills. “As you know, tank-style heaters are continually having to heat and reheat water throughout the day to higher than necessary temperatures, due to heat dissipation through the wall of the tank. This results in stand-by losses of 15-20% of the kWH used,” adds Riley.

“Tankless water heaters are not wasteful, they prove extremely productive, and most importantly, they match water heating production to the homeowner’s use of hot water,” says Bob Hitchner, director of the tankless business unit, Rheem.

Also, check with your tankless manufacturer for federal tax credits offered.

• Space saving -- For example, Stiebel Eltron’s largest Tempra 36 model is only about 22 inches wide, the Tempra 24 about 15 inches wide, both about 15 inches high and 5 inches deep. Compared with the bulky traditional tanks, this can provide a great deal of space saving and present various mounting alternatives. Point-of-use units are even smaller, with our Mini measuring 6.5" high x 7.5" wide and 3.5" deep.
•  Long life expectancy -- Tankless water heaters are here, and their longevity is professed by any tankless vendor you come across.

New trends & technology

Tankless manufacturers are constantly honing their craft. New trends  fall right into the tankless outlook. “The trend toward homeowners transforming master baths to spa-like environments can be best addressed efficiently by tankless,” says Hitchner. “In general, the tankless market can be segregated into three categories: new construction, tank replacement and master bathroom remodels,” Hitchner adds.

Also, consumers are doing their homework and are asking builders to provide them with the most energy efficient products available. “Energy efficient products such as tankless are being used more today by green builders,” says Diane Ford, contractor programs administrator, Bosch Water Heating.

And, “North American gas appliance industries are heading to eco-friendly high efficiency products, and tankless manufacturers are right with them every step of the way,” says Ted Kwak, Navien America Inc.

All this green talk makes everybody warm and fuzzy inside, but it’s time to see results. And tankless has taken the lead in the green department for some time. For example, “Noritz heaters emit a very low amount of toxic gases into the atmosphere, especially with the alarming issue of global warming and construction of “green” homes, which has been the subject of the global community. In fact, at the end of the year, Noritz will introduce the residential condensing tankless water heater which is 93% efficient, making it the best capacity with the lowest emission and highest efficiency in the industry,” says Pan.

And the naysayers?

Sure you’re going to have contractors who just aren’t buying into the concept -- yet. There is just no way tankless can provide endless hot water -- with multiple showers and a dishwasher running simultaneously. Not so fast! The bottom line for fully functioning tankless is proper sizing. “If you undersize a tankless or tank water heater, you won’t be happy,” says Hitchner.

Moreover, “If contractors research the proper sizing of tankless water heaters for the application at hand, they should have nothing but happy customers. As tankless water heaters  are heating cold water as it passes through the unit from a city or well source, there is logically a finite gpm flow rate in order to heat the water to your target temperature -- usually 110 degrees for a good warm shower. Tankless units are dependent on the amount of water flow (gpm), and the amount of temperature rise required (difference between incoming water temp and outgoing from unit). The larger the temperature rise required, the fewer number of gallons per min. can be heated to the set-point temperature. The incoming water temp will vary some throughout the year and thus the curves will shift slightly,” says Riley.

And according to Ford, “All tankless water heaters operate on the principle of degree rise at a certain flow rate. Granted, some manufactures make this information harder to interpret than others.  The key item is to always break it down to degree rise and flow rate for the specific gas type and inlet water temperature.”

Scaling & corrosion

A huge concern heard throughout the plumbing industry is scaling with tankless water heaters, so much so, that in time, you could potentially have a non-functioning water heater. But the tankless experts will tell you that corrosive and heavily mineralized water is going to negatively affect any water heater -- tank or tankless. The answer to the scaling questions varies to some degree based on whom you ask. According to Hitchner, if you are in areas where hard water is prevalent, make sure that the water is conditioned. Isolation valves, or iso valves, can be used to shut off inlet water. “It generally is not recommended to install tankless in areas where the hardness level is above 11 grains,” says Hitchner.

Other answers deviate. “Tankless water heaters are more resilient to scale because they are not always performing a heating cycle. When the copper heat exchanger of the tankless water heater experiences rapid heating and cooling during use, it actually helps prevent scale build up.  Tankless water heaters have no Legionnaire risk, so the temperature is set far lower than storage tanks,” says Ford.

“With tankless, water is constantly flowing through when it is in use, providing only a very small chance for scaling. Only a minimal volume of water is stored in the heat exchanger when the heater is inactive. Therefore it is unlikely for any scale build up. But a couple solutions exist to tackle extreme hard water areas. First, Noritz does offer a scale shield, which is a water softening system that is installed before the cold water inlet to the water heater. This scale shield features a cartridge- type filter, which releases a chemical to break down the scale and balance the pH of the water. This system will help eliminate scale build up inside the tankless water heater. Second, we recommend installing isolator valve kits with all Noritz heaters. The isolator valve kit will allow easy access to the heater’s heat exchanger and by flushing it with vinegar, prolonging the life of the tankless water heater,” says Pan.

On the other hand, “If homeowners live in an area where a high amount of scale is present in the water, they should, regardless of the type of water heater chosen, take precautions against this and consider the use of a water softener prior to the heater. The heating element tanks within tankless heaters are indeed physically much smaller than tank-type heaters, and if scaly water is not treated prior to the heater, they will eventually fill with scale more quickly than tank-types. However, the use of a water softener will extend the life of the unit and under normal water conditions a tankless water heater can last for 20+ years, far beyond normal life span of the tank-type,” says Riley. “Additionally, with our tankless units, the homeowner has the opportunity to limit the temperature the water gets heated to, namely 110 F, or even less depending on personal preference, instead of the 130ºF or more that you need with the tank-type heater. This by itself will reduce the lime build-up. Also, the water is flowing as it is being heated. Both factors reduce problems,” adds Riley.

Tankless installation

The installation of a tankless water should be left in the hands of a trusted p-h-c contractor. According to Riley, if locating the unit where the tank-type once stood, all that is necessary is to bring the cold and hot connections to the inlet and outlet points on the tankless and utilize the existing household pipe runs. He recommends the use of braided steel flexible connectors, but other familiar means of connecting the unit are acceptable. The existing wiring and breakers for the tank-type will likely have to be replaced which is an easy job for the electrician. If relocating, the compact size of the tankless unit gives the homeowner many options for hanging on a wall or placing the unit out of sight in a cabinet. If the plumber or customer opts for hard piping of the unit, caution needs to be used when sweating pipes close to the heater so that the casing is not damaged in the process. After the installation, the filter should be checked for any debris caught in the line from solder or teflon tape, etc., which can often obstruct the water flow and affect minimum water flow activation rates.

This is where new construction benefits with tankless. “If the site can be constructed with the specific ingredients required to run tankless, the install is actually easier. No platform, strapping, pillars or jamming through tight spaces -- tankless is easy for new buildings. Replacing an existing storage tank is a little more challenging than new construction. The contractor has to get the venting, gas and combustion air installed exactly as the manufacture instructs. Deviations on these retrofit items can cause tankless units to underperform,” says Ford.

And Pan says, “The installation of tankless water heaters is pretty much straightforward; they are compact in size and can be installed anywhere in the house -- from the attic to the basement or just retrofitting the current location of the conventional tank water heater. Noritz offers many different type of water heaters to better suit the demand of the end users. However, with all tankless water heaters, the venting will need to be upgraded to a category 3 stainless steel grade material and will not be able to tap into existing chimney or a venting system for convention tank water heater.