How to size electric hot water tank for large retail store (for example, Walmart)? 1

[econ2016]

I know ASHRAE handbook has a table to calculate hot water demand in GPH. But I checked it and other websites, and found space category only for office, apartment, hotel, etc. But there is no data for retail stores. Which building category can I follow to size a tank for retails(Walmart size)?

 

[MintJulep]

A good start would be to count the number of plumbing fixtures using hot water.

 

[econ2016]

In any cases, I know I have to count fixtures. The question here is: what is the demand factor and storage capacity factor to use for the retails? The office is 0.3 and 2, then retails? The "Hot Water Demand per Fixture for Various Types of Buildings at a final temperature of 140°F" did not say that. Thanks a lot.

 

[PEDARRIN2]

Likely the only hot water uses will be lavatories and mop basins.

Since lavatories are 0.5 gpm and only ~60% of that is going to be hot water (depending on the storage temp in the water heater) - the use by the lavatories is minimal for sizing.

The real use (???) will be the mop sink which is a dump load. I would likely size a 4.5 KW (18.45 gph at 100 F rise), 30 gallon water heater and let it go. This will be more than enough for the "diversified load" (~90 uses in an hour) of the lavatories and the dump load (20 gallons) of the mop basin.

 

[MintJulep]

Likely the only hot water uses will be lavatories and mop basins

Unless there is a food court....
or it's a super-Walmart and there is sanitation and cleaning equipment....
or the store has a shopping cart cleaning system....
or....

 

[IRstuff]

These might be useful:

http://www.pdhonline.com/courses/m151/m151conrtent.pdf

https://www.armstronginternational.com/files/products/wheaters/pdf/sizing chart.pdf

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[PEDARRIN2]

MintJulep,

Food courts would be "rentable space" and typically would be required to supply their own hot water heater.

A shopping cart cleaning system, similar to a car wash (though much smaller) would likely be a self contained system with its own heater, filter, pumps, etc.

One thing I forgot to mention is there would likely be more than one toilet room, so each one should have a small water heater.

 

[dbill74]

If you're doing a job for a big box retailer like Walmart, Sears, Home Depot, etc. you need to get a hold of their design standards handbook. It is not unusual for these companies to specify use of particular fixtures, they may even go so far as to provide a recomended size or type of equipment.