Tankless Water Heaters: How Well Do They Work for Restaurants?

The tankless water heater has proven itself a viable replacement for standard storage-type water heaters in residential and light commercial applications. But how well do these types of hot water delivery systems work in locations that call for a continual, high-volume supply of hot water? In general, tankless water heaters can work just as well as storage-based models for a restaurant or other heavy-use commercial facility. At the same time, they’ll provide the benefits of increased efficiency, energy savings and cost reductions that tankless models are expected to provide.

How Tankless Water Heaters Work

Tankless water heaters, as their name suggests, do not have a storage tank where hot water is kept until it’s needed. Instead, these appliances produce hot water on demand. Heating elements powered by electricity or gas-fired burners quickly warm incoming water to the required temperature. The hot water is then delivered at the sink, tub or other fixture as normal. This method of producing and delivering hot water makes tankless water heaters extremely efficient. Since no hot water is kept in a tank, there’s no chance that the stored water will cool down and need to be reheated. There’s also no chance of a tank of hot water going dry during high-usage times or when hot water is needed for dishwashing or other types of sanitation.

The Importance of Sizing, Flow Rate and Temperature Increases

In a restaurant or other commercial setting, three very important concepts will drive the selection of tankless water heaters: size, flow rate and temperature rise. Typically, more than one tankless water heater will be necessary to supply a restaurant’s hot water demands, but the number of heaters and their capacities (size) will depend on the required flow rate and temperature rise.

• Sizing: Sizing tankless water heaters involves determining how much capacity each unit must have to produce the amount of water required for the restaurant’s operations. The units must be sized properly to ensure that there’s enough hot water to meet needs at the time of highest demand, such as a lunch rush or the evening dinner hours. Proper sizing requires that you and your plumbing professional know the required flow rate and temperature rise the tankless unit must provide.
• Flow rate: Flow rate is the amount of hot water, in gallons, that must be produced every minute to satisfy the restaurant’s highest level of demand for hot water. Flow rates in a restaurant or other commercial setting are usually quite high. To determine flow rate, first inventory which hot-water devices are most likely to be in use at the same time and how much hot water they will require. In a restaurant, this must include sinks for washing dishes, hot water for food preparation, and restroom facilities for your customers. Add up the total amount of hot water required all these functions. The total gallons of hot water is the flow rate, or the amount of hot water the tankless system must be able to produce to meet the highest levels of demand.
• Temperature rise: Water coming into your restaurant must be heated to the required temperature before it can be used. The difference in temperature between water when it enters your building and when it is hot enough to be used is the temperature rise. For example, if your utility company delivers water at 50 degrees and you need hot water at 130 degrees, the temperature rise is 80 degrees. The tankless system must be able to heat water to this level consistently and with little variation in temperature.

Our goal is to help educate our customers about Plumbing, HVACR, Fire Protection and Alarm Systems in Commercial, Industrial and Residential settings. For more information on tankless water heaters and their use in large commercial settings, such as restaurants, contact Sobieski.