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Understanding Water Heating Systems and Sizing

What factors, either internal or external, influence selection?

CHICAGO — While your store’s washers and dryers provide your customers the means to wash and dry their clothes quickly, it’s your behind-the-scenes workhorse, the water heater, that supplies the warm and hot water they need cycle after cycle.

If you rely on your distributor, an engineer, or some other project planning professional to determine the style and size of water heater that best fits a laundry, you’re not alone.

But while you may not be doing the calculations yourself, it’s still a good idea to understand the basics of water heating selection and sizing.

Jeff Deal is the director of sales for Hamilton Engineering, which has been supplying water heating equipment exclusive to laundry applications since 1981. His company’s database contains information on an estimated 12,000 individual washer models made throughout the years and their water usage.

“Brand by brand, model by model, there’s a pretty significant variation in the water usage by model,” Deal says, adding that today’s equipment is much more efficient in that area. “Certainly, if you look at the last 15 years, water consumption has changed by probably as much as 65%.”

Aside from the greater efficiency, a wider availability of wash options has also impacted water usage, he adds.

“With our world of electronics and variable pricing schemes and all that, a number of stores offer a different price, whether it’s cold water, warm water, or hot water, so that tends to also decrease the usage of hot water a little bit because somebody doesn’t want to pay an extra 50 cents or a buck to have it be hot.”

Deal says there are four basic water heater styles:

  • Tankless, often wall-hung, with cold water coming in and hot water going out, with no storage.
  • Self-contained tank type, which heats the water from within the unit.
  • Circulating tank type, with a water heater paired with a storage tank and the water circulates between them.
  • Indirect hot water boiler.

Daniel Orr owns National Combustion Co. (NATCO), which has been selling water heaters to the laundry industry for decades.

“In general, what I like to tell people is, every region is different, every store design is different, and there’s no cookie cutter way to say one system or another is the best for a particular store,” Orr says. “That’s where distributors should come in, typically, with an idea of what’s worked for their customers and what hasn’t worked for their customers.”


When sizing a water heater for a self-service laundry, the first step is looking at a store’s peak usage period and then working backward, Deal says.

“What you have to look at is what’s my busiest hour of any given week,” he explains. “I say week because, sometimes, Monday, Tuesday, Wednesday, it’s like a bowling alley in there and you could throw a ball and not hit anything. Saturday and Sunday, you can’t move. So we have to worry about that busiest hour.”

The washer brand/model, the quantity of machines, and their capacities all factor into water heater selection and sizing.

“Then the next pieces are, in that busiest hour, how many turns you’re going to have by each size of washer,” Deal says. “Sometimes, you’ll find the 18- and 20-pounders—what the industry likes to call the single loader—gets far more turns than the triple, the quad, even the 80- or 100-pound machine. You really look at your maximum expected turns that busiest hour.”

“Generally, the fundamental issue is what does a peak day look like. What does a Saturday or Sunday look like?” Orr says. “In some dense urban areas, I hear numbers as high as 10 or 12 turns per peak day. But in other areas, it’s more like six or seven. Yes, I do size differently based on what the expectation is. Typically, what I ask is what is a good store doing in that area on a peak day, because nobody’s looking to build a bad store.”

Next, it’s your audience. The location of your store will play a part in how much hot water is used.

Deal described a study from many years ago comparing two identical laundries built by the same distributor and featuring the same quantity and models of washers. One was on an affluent college campus, the other was in blue-collar Chicago.

“The store at the college campus used a quarter of the hot water as the store in the blue-collar neighborhood in Chicago,” Deal says. “If you use the rule of thumb: I’ve got so many washers, so I need this water heater, no. Who’s your audience? Who’s actually using the water and how much hot water do they want in the percentage of what they’re doing in their wash?

“College kids are scared to death of ruining clothes, so they put everything in cold. The factory workers are going, ‘I’ve got to get the grease and grime out,’ so they throw it all in hot.”

Another aspect of location that should be taken into account is the local water quality, Orr advises.

“In New York City, we’ve got water that’s well balanced; it’s got a little bit of minerals but not a lot,” he explains. “Then you’ve got places like southern Idaho where (the water) is incredibly full of calcium. And then you’ve got areas where the water is soft in the fall and the winter and is hard in the spring, like Ohio or places in a river valley.”

Another location-related selection factor is the inlet water temperature, Orr says.

“Typically, we heat water to somewhere between 120 and 130 degrees,” he says. “If you’re in Miami, you start at 80 degrees and then you need a 40-degree rise to go up to 120. In New York, you start at 40 (degrees) or lower in the winter. … Places where you get water from deep in the ground, it’s 50 degrees, so you’re going from 50 to 120. That’s a big difference.”

Aside from the expectations related to running a self-service laundry, if ownership is contemplating taking on commercial accounts, that, too, can change the nature of a sizing because of the quantities and types of goods that will be laundered, he says.

Where wash-dry-fold work is typically done in an ordinary water temperature range, commercial laundry work can require much higher temperatures to enhance stain removal.

“It’s important for everybody to know if a laundry is intending to take on, say, gym towels, or massage parlors, or whatever,” Orr says. “A lot of places in the upper Midwest or Texas, they also have separate rooms for processing uniforms or other materials from oil or natural gas workers.”

If a distributor has a new store project in the pipeline, Orr suggests enlisting the aid of a water heating company early in the process.

“That’s not just to get the water heating system right,” he says. “Water heating people are often experienced in mechanicals generally in laundries and can keep people away from making mistakes that cause problems.”

If a store ends up sizing its water heating system poorly, what could be the result?

“It’s a pretty big investment for most laundry owners,” Deal says. “In my speeches over the years, I’ve said it’s your single most expensive piece of equipment when you look at it as a stand-alone piece of equipment. If you undersize it, it’s going to basically work itself to death in a very short period of time. You’ve thrown that investment out the window. If you’d sized it properly and it worked as designed, you’d get a nice long life, assuming proper installation and maintenance.”