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Variable Speed Pumping in Condensing Boiler Systems Get the Savings you paid for! October 9, 2012.

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Presentation on theme: "Variable Speed Pumping in Condensing Boiler Systems Get the Savings you paid for! October 9, 2012."— Presentation transcript:

1 Variable Speed Pumping in Condensing Boiler Systems Get the Savings you paid for! October 9, 2012

2 Page 2 Brian Hammarsten, CEM – Trade Relations Manager at Xcel Energy Peter Vinck – Senior Energy Efficiency Engineer at Xcel Energy Russ Landry PE, LEED® AP - Senior Mechanical Engineer at the Center for Energy and Environment Presenters

3 Page 3 Life Cycle Cost of Hot Water Systems Demand Side System Opportunities Transmission System Opportunities Supply Side System Opportunities Next Steps Overview

4 Page 4 Condensing Boiler 1 MMBTU boiler purchase = approx $20,000 Lifetime cost for the gas to operate boiler = $112,800 Of the total cost of ownership, only 17% goes to the purchase price of that boiler Circulator Pump 5 hp pump costs = approx $2,000 Lifetime cost for the energy to operate pump = $26,750 Of the total cost of ownership, only 7.5% goes to the purchase price of the pump Component Life Cycle Cost

5 Page 5 Traditional Boiler LCC Example Page 5

6 Page 6 System LCC* – Condensing Boiler, 2-way valve to heat exchangers, vfd on pump Total Equipment = $53,000 1 MMBTU condensing boiler purchase = $20,000 Valves & Piping modifications = $8,000 Pump and Drive package = $5,000 Labor and misc materials = $20,000 Total Energy Costs = $202,650 Lifetime cost for gas= $112,800 Lifetime cost for pump = $26,750 Lifetime cost for fans = $63,100 Of the total cost of ownership, only 15% to 30% goes to the purchase price of the initial equipment purchase * This is a theoretical example System LCC

7 Page 7 Demand Space heating Domestic water Process Transmission (Piping, Pumps & Valves) Pumps Piping Coils Supply Side Condensing boiler Combustion air fan Feed water pump Controls Hot Water Systems

8 Page 8 Demand side opportunity investigation Temp set points? In your process do you really need 190 degree water or will 175 work? Outside air temperature supply water reset temperature Domestic Hot Water heating in off season Demand Side Opportunity

9 Page 9 Outside air temp. vs supply water temp Temperature resets can be a great opportunity you might be missing during the higher outside air temperatures. Giving you lower losses due to over heating as well as lower return water helping a condensing boiler. Page 9

10 Page 10 Boilers are left in operation to support domestic hot water heat during summer. Consider separating the systems in order to increase efficiency of domestic hot water year round. This would save on equipment life, energy costs, redundancy, etc. Demand Side (cont.) – Domestic Hot Water heating in off season

11 Page 11 Reducing Pumping Costs Reduced System Flow Benefits Transmission Opportunity

12 Page 12 If you have anything in this list, you may have some opportunity to reduce cost. Throttle valve-control system Bypass (recirculation) line normally open Multiple parallel pump system with same number of pumps always operating Constant Pump operation in a batch environment or frequent cycle batch operation in a continuous process Cavitations noise (at pump or elsewhere in the system) High system maintenance Systems that have undergone change in function Reducing Pumping Costs

13 Page 13 Reduced transmission (pump) energy Improved efficiency of condensing boiler Reduced maintenance cost Reduced System Flow Benefits

14 Page 14 Big Savings Potential Unique green investment opportunity when replacing boiler or building new building >15% ROI for some projects But… Savings Depend Heavily on Operating Conditions New construction optimal design very different from typical boiler system Retrofit situations must be carefully evaluated Supply Side Opportunity Applying Condensing Boilers

15 Page 15 Efficiency Levels of Gas-Fired Hot Water Boilers

16 Page 16 Water Vapor Generated by Burning Natural Gas is Condensed Water vapor is natural product of burning natural gas About 12% of flue gas is water vapor, but…. Condensing Energy 2,000°F of Vapor Temperature Drop Condensation Only Occurs at Low Water Temperatures Flue gas dewpoint ~130°F Efficiency keeps improving as temperature drops How Condensing Boilers get that Efficiency Boost

17 Page 17 Getting The Rated Efficiency Boost Out of Condensing Boilers (>90% Efficiency)

18 Page 18 Chart for Showing Moisture in Air Issues Curve at Top Shows When Air Cant Hold Any More Moisture (aka dewpoint or saturated) Once at the Top, Cooling More Condenses Moisture Out of Air

19 Page 19 Applying Condensing Boilers vs Furnaces

20 Page 20 Applying Condensing Boilers vs Furnaces

21 Page 21 Applying Condensing Boilers vs Furnaces

22 Page 22 Three Rules for Energy Value of Condensing Boiler System 1) Return Water Temperature! 2) Return Water Temperature! 3) Return Water Temperature!

23 Page 23 Getting Heat Into a Space in a Building: Typical Central System Gas, Coal or Oil 3,500 – 4,000 F Gas, Coal or Oil 3,500 – 4,000 F Avg Boiler Water 170 F Boiler Radiators Air Handler/VAV Mixed or Cooled Air Mix ~350 to 400 F Page 23

24 Page 24 Central System Designed for Condensing Boiler Gas at 3,500 F Boiler Water 160 F Average Boiler Radiators Heated Air Mixed or Cooled Air Mix Radiant Floor + + Air Handler/VAV Page 24

25 Page 25 Heat Carried by Water or Air Depends on temperature change (TD or T) Depends on water or air flow rate Carrying Heat from One Place to Another

26 Page 26 System Piping: Driving Return Water Temperature Down Typical Flow Low Flow Avoid 3-way/4-way Valves on Main Line Reduced Flow Brings Down Return Temperature If Mixed Boilers – Cold Water & Max Load to Condensing

27 Page 27 Lower Flow (e.g. Pump VSD & 2-way Valves) Pump Energy Savings Low Return Water Temperature = Condensing Boiler Efficiency Improvement If low delta, may be good opportunity in any system Outdoor Reset Control Reduces Load from Overheating & Pipe Heat Loss Lower Return Water Temperature = Condensing Boiler Efficiency Improvement If high temperatures in mild weather, may be good opportunity in any system System & Load Affects on Condensing Boiler Efficiency Boost

28 Page 28 Outdoor Reset Lowers Water Temperature As the heating load goes down, less temperature difference is needed to drive the heat flow. Boiler Water 150 F Average Space 75 F

29 Page 29 Combined Outdoor Reset & VSD

30 Page 30 Getting The Rated Efficiency Boost Out of Condensing Boilers (>90% Efficiency) Page 30

31 Page 31 Traditional Coil-In Tank Requires High Boiler Temperatures Efficiency > Traditional Water Heaters Efficiency Sacrificed with Condensing Equipment Service Hot Water: Driving Return Water Temperature Down 130°F Boiler >130°F

32 Page 32 Product-Specific Issues Small water passages in old cast iron system Pressure drop compatibility with system Flow rate compatibility (short-cycling) Control coordination Dual temperature inlets General Load & System Issues Ability to provide adequate heat w/low return temperatures Ability to reduce flow rate w/out branch balance problems 2-way valves on loads to replace 3-way valves Key Design & Application Considerations: Preventing Problems

33 Page 33 Venting Considerations Design & Installation Details to Deal with Condensate Sidewall Venting Can Cause Moisture Problems With Large Boilers Orphaned Water Heater Vent Cost Key of Hi-Rise Key Design & Application Considerations: Preventing Problems (cont.)

34 Page 34 Space Heating Elements System Piping System ControlPump System ControlTemperature Service Hot Water Key for Condensing Boiler Efficiency: Driving Return Water Temperature Down

35 Page 35 Condensing Boilers Can Be a Great, Green Investment Success Depends on Different Approach by All Minimize return water temperature! High Efficiency Boiler Information Air-Conditioning, Heating, and Refrigeration Institute (www.ahrinet.org) EnergyStar.gov California Energy Commission web site Consortium for Energy Efficiency In Conclusion....

36 Page 36 Utilities offer rebates to customers to help pay for the identification, energy savings quantification, and for the changes once implemented. Check with your electric and gas utility to see what rebates the offer There are several here today Programs to look for: Study (investigation process) – Heating System Optimization, C/I Turn Key, Audits Tune ups – Boiler Tune ups, Steam Trap Leak Study, Recommissioning Prescriptive Measures – O2, Stack Dampers, pipe insulation, new boilers, VFDs, Motors Custom – Insulation of valves, rebates for industrial process heating systems, most demand side measures, piping modifications, adjust temp set points. Utility Key

37 Page 37 Questions?

38 Page 38 The following slides are bonus material that was cut from the final, live presentation due to time constraints. Bonus Slides

39 Page 39 Controlling Excess Air Even More Important Excess air reduces concentration of water vapor Dewpoint decreases Condensing Boiler Sensitivity to Excess Air

40 Page 40 Traditional Factor of Burner Excess Air Is Even More Critical

41 Page 41 Condensing Boiler Comparison to Direct- Fired Heater Page 41 Direct-Fired Heater

42 Page 42 Chart for Showing Moisture in Air Issues Moisture is Much More Diluted in Direct-Fired Heater It Reaches a Lower Temperature, but Never Condenses (T HANKFULLY !) Direct Fired Heater


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