Explore the best products for home water heating - condensing water heaters, from the conventional storage tank and tankless group. Check out how selected condensing models provide ultra-efficient water heating resulting in great savings of over 50%, a high energy factor of up to 0.97, and Energy Star compliance for additional incentives.
Compare Rinnai, Noritz, and Navien tankless water heaters and AO Smith Vertex and Polaris using the conventional tank-type design.
Residential gas-powered condensing water heaters are very popular in Europe, where they are usually called condensing boilers, combi boilers, and cylinders. And, for example, combi boilers in the UK are found in close to 70% of homes.
These are also well-known in North America for commercial use, and because of all the benefits, rising gas prices, and lower operating costs, condensing water heaters are becoming more and more popular in residential water heating applications as well.
Also, the government legislation and higher demand for energy-efficient water heating systems make the condensing heaters a favorable gas type.
What makes the condensing water heaters with the tankless design unique are two heat exchangers, usually made of stainless steel, where the secondary element is added to capture the heat energy from flue gases and preheat the incoming cold water, increasing the efficiency to over 90%.
Due to the tank-less design, water passes through the heat exchanger, generating hot water with no storing and on-demand.
The best condensing and tankless water heaters come from popular brands; Rinnai, Noritz, and Navien.
From the Rinnai manufacturer, an indoor water heater RUR98i is probably the best. Rinnai RUR98i is the most powerful unit with the highest water flow rate of 9.8 GPM and efficiency of 0.95 - ideal for demanding families. The exclusive ThermaCirc360 feature makes it great as the unit can be used in recirculation to deliver hot water fast and therefore save on energy, reducing the wait time and increasing comfort.
An advanced electronics and eco-friendly gas burner, combined with the modulating gas valve, allows this unit to operate from its minimum to the maximum of 199,000 BTU, generating ultra-low NOx gas emission. It comes with a warranty of 12 years.
The best of Noritz is a direct vent model NRCP1112 built for indoor installations only.
NRCP1112 is a condensing water heater that produces a high hot water flow of 11.1 GPM, making it great for large homes with up to 4-5 baths and an energy factor of over 0.9, providing savings over 50%.
Noritz NRCP1112 is equipped with an internal circulation pump with two modes to reduce the wait time for hot water while saving water and energy. The advanced electronics and large control panel interface allow users to take advantage of the heater's programming and diagnostic system to control, monitor and troubleshoot if there is a problem with the water heater.
The water heaters come with a 12-year warranty.
Navien NPE-240A is the premium condensing water heater, one of the largest models from this Korean manufacturer, capable of providing an endless supply of hot water with a high flow rate of 11.2 GPM and amazing efficiency of 0.97. Moreover, a cascade system can be utilized for high-demand applications so multiple units can be connected and operated by one controller.
Navien NPE-240A is equipped with ComfortFlow Technology to eliminate the water temperature fluctuation or cold water sandwiches. The built-in recirculation system ensures faster hot water delivery while the Intelligent Preheating Technology recognizes the pattern usage, all working toward increasing comfort and overall satisfaction. It comes with a warranty of 15 years.
Video: AO Smith Vertex
As opposed to tankless, tank-type condensing water heaters are equipped with one super performing helical heat exchanger, which is surrounded by water. Good examples are AO Smith Vertex and American Polaris, both utilizing a fully condensing design that ensures high thermal efficiency of 96% and performance that rivals much larger heaters.
Polaris condensing water heater, when compared to the same 50-gal size of Vertex, is lighter, more powerful - 199,000 BTU vs. 100,000 BTU; has a much higher recovery rate of 253 vs. 129 gallons and longer warranty of 10 years vs. 6-year warranty of the Vertex, but it costs more.
The flue spirals around and inside the tank so that the combustion gases spend more time releasing the heat until the water vapor in the gas - a natural by-product of the combustion process - condenses, releasing even more energy. The spot where the flue exits the tank is barely warm to the touch.
Another quality component includes the metal fiber burner that is ultra-resistant to stress and corrosive water effect. It is located in the sealed combustion chamber, where it can generate very clean and high-intensity blue flame, resulting in less pollution but intensive heat transfer.
Condensing water heaters are gas-fired units with a similar water heating process as conventional models. The problem with the conventional heaters, the most popular heating systems in America and Canada, is that too much heat energy is wasted when the products of combustion - flue gases are vented out.
A smart solution comes with the condensing and energy-efficient water heaters where the heat of the flue gases is recaptured and used for preheating the cold incoming water, so less heat energy is wasted. These models achieve ultra-efficiency by removing the heat from the burning fuel while cooling the products of combustion, resulting in cheaper venting usage.
That is why the condensing boilers have to have larger and more efficient heat exchangers than traditional boilers, including some other additions.
The water vapor produced by the burning gas in the boiler condenses back into liquid water, releasing the latent heat of vaporization from the water. Because latent heat is a significant source of energy, condensing boilers have efficiency ratings up to 98%.
Condensing water heaters are expensive but have lower operating costs, perform much better (up to 40%) than their standard counterparts, and are equipped with the most innovative features and technology - making them a good buy and long-term investment.