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A restaurant can lose up to $5,000 per serving period if the water heater goes down. Losing hot water in a hotel can mean losing a guest for life. And for prisons, having no hot water can even result in lawsuits.

Reliability is crucial in commercial water heating. So while using multiple propane tankless water heaters can offer building owners improved energy efficiency, reduce capital investment, and lower the overall cost of ownership, the big selling point for many owners is certainty that they’ll always have hot water.

“Having built-in redundancy, where the water heating won’t ever go down, is super important for building owners,” says Ansley Houston, director of the commercial division for water heater manufacturer Rinnai.

The Jackson County (Wisconsin) Courthouse’s rack of six tankless water heaters was shipped to the site pre-assembled, with all gas piping, water piping, combustion-air, and exhaust-air piping and controls already installed.

Propane and natural gas tankless water heaters have been used in commercial applications for nearly 15 years in the United States, Houston estimates, but linking a system of multiple tankless water heaters together used to be a time-consuming process for contractors. Rinnai began to simplify the installation process in 2012 with the introduction of tankless rack systems (TRS): free-standing or wall-mounted multi-unit systems that were shipped to projects fully assembled, including gas and water manifolds.

Today, the company has further streamlined the implementation of commercial tankless water heating systems by moving assembly of the TRS to its American headquarters in Peachtree City, Georgia. There, a commercial applications engineering team can work with building architects and engineers to design a system that best fits the need of individual projects.

“We’re listening to our customers and we’re putting together the configurations that they’re asking for,” Houston says. “Since we’re now assembling the racks ourselves, we have the ability to do custom work when customers are requesting it. And quite frankly, in commercial, most of them are.”

Rinnai’s engineers can customize a solution to prioritize reliability, space savings, energy efficiency, or first-hour water delivery depending on the application, including combining tankless units with storage tanks where appropriate. That’s a vital service with different types of commercial buildings having vastly different needs.

 “The architect can design a building footprint with a zoned tankless system, thus dramatically reducing the space needed for water heaters.”

“Providing two medium-size or smaller tankless units for a quick-service restaurant is a value beyond belief,” Houston says. “It gives you a backup system, and with the ability to rotate on and off, it extends the life of the system.” A larger building like a 130-room hotel might use about 10 units, in racks of 6 and 4. The systems can range up in size to a total of 4.9 million British thermal units (Btu), with 25 tankless units.

Computerized controls allow even such large systems to precisely track the water heating load of a building and activate individual units accordingly. “If only one fixture is on, one unit will fire and it will modulate itself down to just supply that amount of water,” Houston says. “If all the rooms of a hotel are pulling water at the same time, the units will come on as needed and modulate up to high fire.”

Minimal mechanicals

Creative engineering also means that a tankless-based water heating system can require much less space than a traditional boiler or storage tank system. If a hotel is using 10 tankless units, for instance, the architect can put three or four units on every other floor and zone the entire building.

“The architect can design a building footprint with a zoned tankless system, thus dramatically reducing the space needed for water heaters,” Houston says. “The vent piping runs get shorter, and the energy efficiency improves because of how far the water has to travel.”

On the residential side, tankless water heating has traditionally been a higher-cost upgrade, paid for over time in improved efficiency and the promise of never running out of hot water. But on the commercial side, a tankless rack system may be less expensive both upfront and in total cost of ownership. While maintaining or replacing the heat exchanger on a commercial boiler may cost up to $10,000 over the life of the system, a tankless heat exchanger costs only about $300 each or about $2,000 in maintenance costs over the system life.

Rinnai is also making maintenance itself more reliable. The manufacturer now offers factory-authorized maintenance packages, coordinating its own authorized service providers to perform preventive maintenance on a preset schedule. That means the company now offers end-to-end support, from design through installation, start-up, and preventive maintenance.

For commercial buildings without access to natural gas, using propane instead of electric water heating means building owners don’t have to sacrifice the reliability, efficiency, and low ownership costs of tankless water heating. Learn more about how these systems can fit into your next project in the commercial propane tankless water heater fact sheet.

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Jeffrey Lee