Restaurants

When designing a hot water system for kitchen needs at a restaurant, the designer should note that both 140ºF and 180ºF temperature water is required. An ample supply of 180ºF is used for the final rinse on many automatic dishwashers available today and the 140ºF supply of water is used for general cleaning and food preparation. The main concern when sizing a hot water system for a restaurant is supplying adequate hot water to maintain sanitation requirements.

Special Design Considerations

• For estimating purposes it can be assumed that 1.5 gallons of 140ºF is required for every meal served.
  
• The type of dishwasher in addition to the manufacturer, model number and the rinse cycle requirement is essential to properly sizing the hot water system. It is essential to note that some dishwashers have a high GPM flow rate and a low GPH consumption or a low GPM flow rate with a high GPH consumption.
  
• When sizing for small diners, the calculated First Hour Rating can be reduced as much as 30% in some cases. This reduction is based on the needs of the facility for food preparation and dish washing.
  
• When sizing for hotel restaurants or restaurants which serve elaborate meals, the calculated First Hour Rating should be increased as much as 25% in some cases. This increase is again based on the needs of the facility for food preparation and dish washing.

General "Rules of Thumb" For Sizing

Food service establishments	Max. hour	Max. Day	Avg. Day
Type "A"
Full meal restaurant/cafeterias	1.5 gal/max. meal/hour	11.0 gal/max. meal/hour	2.4 gal/max. meal/hour
Type "B"
Drive-ins, grilles, luncheonettes, deli shops	0.7 gal/max. meal/hour	6.0 gal/max. meal/hour	0.7 gal/max. meal/hour

Hot Water Demand per Fixture Detail Sizing - Kitchens

Fixture	Gallons of water per hour per fixture (calculated at a final temperature of 140ºF)
Vegetable sink	45
Single pot sink	30
Double pot sink	60
Triple pot sink	90
Pre-scrapper (open type)	180
Pre-flush (hand-operated)	45
Pre-flush (closed type)	240
Recirculating pre-flush	40
Bar sink	30
Basin, lavatory	5

National Sanitation Foundation NSF Final Rinse Water Requirements for Dishwashing Machines

Type and sink of dishwasher	Flow rate gpm	Hot Water requirements at 180ºF to 195ºF maximum
		Heaters without internal storage gph	Heater with internal storage gph
Door type:
16 X16	6.94	416	69
18 X18	8.67	520	87
20 X 20	10.4	624	104
Undercounter type	5	300	70
Conveyor type:
Single tank	6.94	416	416
Multiple tank (dishes flat)	5.78	347	347
Multiple tank (dishes inclined)	4.62	277	277
Silver washers	7	420	45
Utensil washers	8	480	75
Make-up water requirement	2.31	139	139

Method of Sizing

1. Determine the number of fixtures required for the application and calculate the total hot water demand for those fixture.

Number of Fixtures x Gallons of Water per Hour per Fixture = Possible Maximum Demand

2. Determine the Probable Hot Water Demand for the application.

Probable Hot Water Demand = Possible Maximum Demand x Demand Factor

Demand Factors: Kitchens = 1.00

3. Compare the Probable Hot Water Demand with the 1st Hour Performance Ratings of the Phase III Indirect Water or with the Heat Master Direct Fired Water Heaters.

To convert 180ºF Hot water Demand to 140ºF Hot Water Rating:

180ºF Probable Hot Water Demand x 1.50 = 140ºF 1st. Hour rating

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