RFMA 2016 March 13 15

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1 Your Hot Water System: The Hidden Costs and Opportunities? Amin Delagah Research Engineer 03/15/16 Working with Utilities, Government, & Industry Groups AND the Countless End Users! 1

2 What we ve been doing for 25 years... Appliance Testing Real World Energy Use Monitoring Kitchen Ventilation Laboratory Site Survey/Energy Audits Equipment Specification Review Facility Design Assistance Publications Seminars Utility Food Service Equipment Rebates Online Resources Your online toolbox Reports Energy saving tips Design guides Cost calculators Energy Star Rebates Free Design Guide Available Saving water and improving system efficiency through innovative design strategies and bestin class technologies! waterheating/ 2

3 Learning Goals Typical hot water use and cost Learn ways to improve the operating efficiency and hot water delivery performance of hot water systems Good operating and maintenance practices Examples & cost calculators Results from field monitoring studies Identify emerging technologies for optimizing hot water delivery performance Estimate of 3.5 billion Therms in US Food Service for Water Heating sanitation 18% refrigeration 6% water kitchen exhaust and ventilation 11% air building HVAC 17% food prep: all other 13% hot food food prep: basic cooking appliances 22% lighting 13% Every Drop of Hot Water Costs You Three times: Water Heating Energy Sewer Treated, heated, and deleted 3

4 Restaurant Hot Water Costs 0% Annual Increase 6.5% Annual Increase 1% Annual Increase Hot Water Use (gal/d) Gas Use (therms/y) Gas Cost Water and Electricity Sewer Cost Cost Annual Cost Quick Service Full Service 500 1,600 $1,600 $1, $3,500 2,500 9,300 $9,300 $9,700 $4,700 $23,700 Hot Water System Design Strategies The way that hot water systems are designed, installed and operated hasn t changed much in recent decades. Emphasis on conventional systems with a lower (design, purchase, and installation) installed cost Standard efficiency heaters Inefficient distribution systems Poor hot water wait times at hand sinks Good News: Lots of opportunities for improvement Help offset the installed cost premium Achieve operating savings Better performing system Distribution systems Improving the Efficiency Hot water delivery Hot water generation 4

5 Standard Efficiency Tank-Type Flue Damper Water Outlet Water Inlet Burner Gas Inlet Standard Efficiency Tank-Type Pros Simple Robust Low cost Industry standard Easy to specify Easy to fix Easy to replace Cons 80% thermal efficiency Standby loss (100 gal): Btu/h High Efficiency (Condensing) Tank-Type Blower Air Inlet Burner Water Outlet Water Inlet Exhaust 5

6 High Efficiency Tank-Type Pros Condensing 95% efficiency Standby loss: Btu/h Potentially lower cost of installation Cons More complex Manage Condensate Not the standard Higher first cost Storage Heater Limitations Can run out of hot water during heavy usage if undersized Life of the unit can greatly be compromised if undersized Tankless (On Demand) Standard Efficiency Tankless Pros Smaller footprint Outside installation possible No standby loss Cons Significant pressure drop Minimum water flow limits Each unit provides a water flow of approx. 4 gpm Probably need several units Higher gas inputs rates = higher installation costs Increased maintenance required 6

7 Tankless Heater Limitations Startup sequence creates an additional lag in hot water delivery A couple of seconds before it wakes up seconds before its close to set temperature Cold water sandwich effect Difficulty working with door type dishwashers and low flow aerators on hand washing sinks Tankless Heater Limitations Doesn t work well with recirculation systems w/o expansion of system Making it work requires additional investment Most heaters are not designed to modulate down to accommodate a 5 to 15 F temp rise The heater can continuously cycle on/off which may create excessive cycling and the build up of condensation in the flue, causing shutdowns May nullify or shorten manufacturer s warranty Hybrid Storage/Tankless Photo Credit: IntelliHot 7

8 Hybrid Storage/Tankless Pros Benefits of both storage and tankless units Smaller footprint Outside installation possible High efficiency only Cons May need multiple units or auxiliary storage tank Maintenance may be higher Standby Losses CEC Funding for Research at PG&E Applied Technology Services ANSI TE Test at PG&E ATS Lab Standby loss of HE tank is 670 Btu/h versus SE tank at 1650 Btu/h 8

9 Effect of Inlet Water Temperature on Thermal Efficiency of Condensing Tankless System Delivery Efficiency = High Eff. Tank Type High Eff. Storage Std. Eff. Storage Std. Eff. Tankless Effect of Recirculation on System Efficiency in QSR Without recirculation With recirculation High efficiency heaters can t condense much with recirculation pumps! High Eff. Storage Std. Eff. Storage High Eff. Tankless Std. Eff. Tankless 9

10 Simple Distribution Uses a trunk, branch and twig configuration to deliver water from the heater to the point of use Benefit: compatible with all heater types Drawbacks: long wait times at hand sinks Typically designed for QSR where each line is kept to 60 feet or less Two common systems: single line and two line distribution providing 140 F water to sanitary equipment and 100 F 120 F to hand sinks Branch Twig Trunk Two Line Simple Distribution 120 F Line 140 F Line 120 F Line Prep Sink Hand Sink 2 3-Comp Sink Mop Sink Hand Sink 1 Lavatory 2 Lavatory 1 Continuous Recirculation Task is to keep the distribution line hot at all times like moving the heater much closer to the points of use Drawbacks: this method does not always ensure that hot water makes it to the faucet High operating costs are incurred in a typical FSR as 140 F water circulates all the time constantly loosing heat to the surroundings 10

11 Demand Circulation The task of demand circulation is to circulate hot water in the supply line and down to specified fixtures on demand and deactivate automatically when hot water has reached its target. Demand circulation saves energy and improves hot water delivery. Demand Circulation with Optimized Distribution 120 F Line 140 F Line Place the heater(s) in a central location 120 F Line Demand-circulation pumps Mirror the men s and women s lavatories Distributed Generation A hybrid system that is a combination of electric tankless heaters at remote hand sinks and a simple distribution system in the kitchen fed by a water heater placed centrally Benefits: works well with low flow aerators, saves energy and increases hot water delivery performance 11

12 Hybrid System w/ Electric Tankless Cold Water Line 140 F Line Electric Tankless Heaters Reducing Heat Loss from Piping Add pipe insulation on all hot water lines Extends the cool down time Improves the effectiveness of the distribution system Reduction of unwanted heat gain to air conditioned spaces 1 thick insulation is the law for 2 diameter pipes or smaller (Title 24) Install a timer on the recirc line Retro-Commissioning Results from ATS Lab System delivery efficiency of a distribution system with 1 thick insulation 12

13 Retro-Commissioning Results from ATS Lab System delivery efficiency of a non insulated distribution system dropped by 9%! Hot Water Delivery Problems Dishwashers and hand sinks are two areas where getting hot water to the point of use is critical For good dish cleaning and sanitation inlet water at 140 F is typically required to feed low temp dishwashers or booster heaters for a high temp machine Handwashing requires 100 F to 108 F hot water in a timely manner for good hand sanitation Hand Sink Delivery Problems from a High- Foot-Traffic Facility with no Recirculation 1 month data set Recorded 10 sec data intervals Filtered only for flow periods Sorted by temperature Temp. deemed satisfactory for hand washing if >100 F Results of testing 100 F water reached the lavatory 14% of the total draw time and the staff hand sink only 3% of the total draw time 13

14 Long Branch Piping Restrooms 25ft Kitchen Bar 16ft HS Poor hot water delivery performance at hand sinks Question: How many seconds does it take to get hot water from the recirculation line to lavatory sink with a 0.5 gpm aerator on faucet? seconds (acceptable) seconds (marginal) seconds (unacceptable) seconds (unacceptable) 25 feet in length ¾ -inch dia. pipe Answer: How many seconds does it take to get hot water from the recirculation line to lavatory sink with a 0.5 gpm aerator on faucet? seconds (acceptable) seconds (marginal) seconds (unacceptable) seconds (unacceptable) 14

15 Hand Sink Delivery Solutions Follow guidelines for sizing branch pipes to public hand sinks with 0.5 gpm aerators Serves 1 2 Lavatories: 3/8 Diameter Serves 3 4 Lavatories: 1/2 Diameter Serves 5+ Lavatories: 3/4 Diameter Dropping the recirculation line vertically will reduce the length of branch or twig piping 5ft 8ft Fix Leaks and Do Maintenance Don t thaw with running water: That s a leak that you created! 15

16 How much is that leak costing you? collect one minute of leak and measure Use leak calculator 60 gal/day at 180 F Stage One 16

17 Stage Two Dishmachines can be very leaky! Case Study: Medium-Sized Hotel Operator spent $3,000 to tune up dishwasher. But, technicians missed 9,000 gal/d leak. Issues: Bad rinse pressure regulator Malfunctioning fill 17

18 Make sure the rinse pressure is properly set and then make sure the gauge is working! Take-Away? On a high temp dishwasher, if rinse temp is running consistently low, your rinse flow rate may be out of spec (1) Check to see if pressure gauge is working, calibrated, and set to correct pressure. (2) Check rinse nozzles, may be worn out and using too much water. Check Hot Water Use vs. Specs Measure hot water use at an open drain from the dishwasher Weigh the amount of wastewater on a scale in lbs. Divide by the specific weight 8.2 lbs./gallon at 140 F On a door type unit, measure water use of one rack (gal/rack) On a conveyor unit, measure water use in one minute of continuous operation (gal/min) Compare to original specs 18

19 Broken Fill Cycle? Do a visual check of the water going down the drain when the machine is NOT in the rinse cycle. Look for water waste even when you don t expect it! What s happening here? Dangling rinse sensor finger caused a 10 hour rinse cycle Replace Worn Racks 19

20 Check and Optimize Dishroom Operations Optimize Operations: Use Custom Racks Washing sheet pans or cutting boards flat on the rack causes wash water to spray in to the rinse section or on to the load and unload tables triggering a tank fill operation To minimize water carryover from wash tank, utilize custom racks and angle unload and load tables to drain water back into machine Check Operations: Look for operator error Manual Override = 1740 gal/d of water waste 20

21 Check Operations: Rack Loading Efficiency With larger rack conveyors and flight machines, short staffing the dishwasher can greatly increase the energy and water use of the dishwasher Inefficiencies occur when the gap between racks increases Provide enough table loading and unloading space to wash racks in batches of 5 10 racks Check Pre Rinse Operations Comparison of 2 kitchens on the same corporate campus Are they using a high pressure low flow spray valve or not? How about that scrapper, how is that being operated? Big difference in hot water use Site 1 used only 1.15 gpm PRSV, consuming 75 gal/d Site 2 used 2.5 gpm PRSV with scrapper and degreaser running continuously using 3,145 gal/d Check Pre-rinse Operations Are they using the high pressure pre rinse spray valve or are they dragging over the industrial hose used for floor cleaning? 3 Hoses, total use of 1,282 gal/d High flow rate of 5 to 7 gpm Savings potential of 1,000 gal/d from changing to 1.15 gpm spray valves 21

22 Or we can Maintain the Status Quo Restaurants are an Energy and Water Intensive Operation Responsible for up to 75% of the hot water utility costs. Heavy Dishwasher Use in FSR 22

23 AVG. Results From Monitoring 18 Conveyors Efficient rack conveyor dishwashers on average used 60% less water and 65% less energy than conventional units Old: 690 gal/h 1,500,000 Btu/h New: 260 gal/h 530,000 Btu/h Efficient flight conveyor dishwashers on average used 75% less water and 55% less energy than conventional units Old: 1120 gal/h 1,430,000 Btu/h New: 270 gal/h 650,000 Btu/h Don t drill out the spray nozzle! Buy a New One 1.42 gpm rated nozzle converted to 4.6 gpm = 70,000 gallons of hot water/yr = $1,500 increase in annual operating cost! Online Pre-Rinse Spray Valve Calculator 23

24 Online Pre-Rinse Spray Valve Page Spotlight of Advanced Dishwashers Energy Flow Diagram Heat Loss Heater and distribution system: ¼ heat loss Exhaust air: ¼ heat loss 140 F 180 F Minimal heat loss to dishes 65 F Water heater: 2/3 energy input Energy Input Electric booster and wash tank heater: 1/3 energy input Drain water: ½ heat loss 24

25 Drain Water Heat Recovery Device Uses a double wall heat exchanger to transfer heat in wastewater that would otherwise be wasted to preheat supply water Readily retrofittable with existing conveyor and door type machines Find report at: High-Temperature Dishwashers with Heat Recovery Can Save Even More Energy Exhaust-air heat recovery (EAHR) preheats incoming cold water saving energy at the water heater. Cold water passes through copper pipes while a fan extracts steam and forces it through thin aluminum plates. The steam condenses on the cold fins and the latent heat is transferred to the cold incoming water. The cold supply water at a minimum of 50 F can be preheated to F before reaching the booster. Photo Credit: Winterhalter Laboratory Testing: Convective Heat Load 25

26 Operation of High Temp. Undercounter Unit High temperature dishwashers eliminate the need for chlorine sanitizer that may affect the smell or taste of the drink Require a hot water connection at 140 F to bar Using high temperature water to sanitize does generate a big plume of steam when door is opened Without Heat Recovery Undercounter Unit Operation With Heat Recovery Very little steam is produced after each cycle Requires only a cold water supply to operate Provides consistent results batch after batch With Heat Recovery EAHR Dishwashers Available in the U.S. Door Type: Cold Water Feed Only 26

27 EAHR Dishwashers Available in the U.S. Rack Conveyor: Flight Conveyor: Optional Heat Pump Thank you for your Attention! Phone: (925)