PDF《Design Guide》

Design Guide C Energy Efficient Water Heating, Delivery and Use C 3.

26.10 Introduction This document guides the restaurant designer or engineer to use innovative strategies that will deliver the service of hot water as efficiently as possible while meeting the increasingly challenging regulatory codes and user expectations. This is fundamentally a four-step process: (1) reducing hot water use of equipment and faucets while maintaining performance;

(2) increasing the efficiency of water heaters and distribution systems;

(3) improving hot water delivery performance to hand washing sinks;

and (4) incorporating free-heating technologies like waste heat recovery and solar pre-heating. Through high-efficiency system design and equipment specifications, the potential exists to cut the energy use for water heating restaurants in half. Background Hot water is the life-blood of restaurants. The hot water system provides the service of hot water to clean hands, wash dishes and equipment, and for cooking purposes. For food safety reasons, foodservice facilities are not allowed to operate without an adequate supply of hot water for sanitation. Therefore it is essential to design the water heating system to meet the needs of hot water using equipment under peak operation. Design Guide Improving Commercial Kitchen Hot Water System Performance Energy Efficient Heating, Delivery and Use The information presented is applicable to new construction and, in many instances, retrofit construction. The target audience consists of kitchen designers, mechanical engineers and contractors, code officials, foodservice operators, property managers, plumbing professionals and maintenance personnel. This guide reviews the fundamentals of water heating for commercial food service and describes the design process. It concludes with real-world design examples, illustrating the potential for a high performance, energy and water efficient system. It is a supplemental guideline that complements current design practices (ASHRAE Handbook 2007) and codes. Introduction and Background

1 Fundamentals

3 Design Path for Savings

4 Equipment and Fittings

5 Distribution Systems

9 Water Heater Selection

15 Solar Thermal and Heat Recovery

26 Summary

27 Top Design Tips

28 Example

1 Full Service

30 Example

2 Quick Service

37 Improving Hot Water System Performance Design Guide C Energy Efficient Water Heating, Delivery and Use C 3.26.10

2 Restaurant operators expect: (1) unlimited access to hot water, (2) immediate hot water delivery to faucets and equipment, (3) a system that is reliable with little or no maintenance, and (4) minimal investment and operating costs. Unfortunately owners'

expectations of their hot water system are rarely met. Moreover, the performance of hot water distribution systems is in decline;

when we turn on a hand-sink faucet it can take a considerable amount of time to get hot water (if it gets there at all). It is time to rethink the design of hot water systems to effectively integrate food safety, plumbing, and efficiency regulations and take advantage of high-efficiency water heaters, advanced distribution concepts and efficient water- using equipment through a holistic design process. Water and Energy Saving Potential Foodservice operations in California consume upwards of

350 million therms of gas annually for water heating C representing 15% of the total gas consumed by commercial buildings in California. They also use an estimated 115,000 acre-feet of water per year. The saving potential is considerable and in great need. Our freshwater resources are under siege and it is becoming a struggle for communities to meet the water and energy needs of a growing population. Annual Operating Costs An unyielding upward trend in utility costs in the U.S. of 6% annually C well above the annual inflation rate of 3% C is troubling for the foodservice sector. For the restaurant owner, this means a larger portion of revenue will be needed to pay for utility costs associated with the hot water system. The annual cost for conventional water heating systems operated in California in a typical quick-and full-service restaurant is displayed in Table 1. The projected operating cost of $3,500 and $19,650 translates to a substantial portion of the restaurant'