Efficient Condensing Boiler Design for Commercial Buildings

1. Presented by: Terry Stohs Viessmann Manufacturing Company Inc.

2. Design Challenges in Commercial Building. Efficiency Regulations Mechanical Room Space Customer Comfort Installation Cost System Design Operational Cost System Longevity System Integration(BMS) Initial Investment Return On Investment

3. Whatmakes a Condensing Boiler Condense?

4. LATENT HEAT 10.2% SENSIBLE HEAT 89.8% Latent – Definition: Latin for “hidden” Heat that can be measured or felt by a change in temperature ENERGY CONTENT OF NATURAL GAS

5. CH4 + 2 O2 CO2 +2 H2O HEAT RECOVERY FROM FLUE GASES Water vapor (steam) containing latent heat How do we capture the latent heat? • Simplified Chemical Combustion Formula:

6. 99.8% THE MOST EFFICIENT BOILER MARKETING AND REALITY AFUE Combustion Efficiency 98% EFFICIENT Thermal efficiency ….can reach efficiencies of 98% - and more…..

7. What Are The Test??

8. Air Input 180oF 80oF Fuel Input COMBUSTION EFFICIENCY TESTINGFor condensing gas commercial boilers >300 MBH BTS-2000 ∆T=100°F Constant Load Heat Exchanger Efficiency is manually calculated using formulas in BTS-2000 or CSA B140.7 - 05Efficiency is manually calculated using formulas in BTS-2000 or CSA B140.7 - 05 Condensate measured for condensing boilers test

9. BTS-2000 ∆T≥100°F TOUT TIN – Fixed water temp (35-80oF) QIN Heat Input, btu/h W= Mass of water (lb) Boiler Condensate measured for condensing boilers THERMAL EFFICIENCY TESTINGFor commercial gas or oil boilers >300 MBH NOTE: In some appliances the combustion and thermal efficiencies are so close that the thermal efficiency can actually be measured higher than combustion efficiency. This can be due to a very well insulated jacket (low standby losses), the testing environment (space warmer than Return Water Temperature) and small errors in the test results. ANSI Z21.13 / CSA 4.9-2007

10. Condensing boiler Total heating value Heating system Sensible heat Useable heat Condensation What influences the rate of condensation? Latent heat MORE USABLE HEAT THROUGH CONDENSATION

11. Do All Condensing Boilers Perform Equally? Remember, efficiency depends on the rate of condensate formation!

12. Burner type Fuel Piping layout Heating system Return water temp Govt regula-tion FACTORS INFLUENCING EFFECTIVENESS OF CONDENSING TECHNOLOGY Effective use of condensing technology

13. Govt regula-tion FACTORS INFLUENCING EFFECTIVENESS OF CONDENSING TECHNOLOGY Effective use of condensing technology

14. FACTORS INFLUENCING EFFECTIVENESS OF CONDENSING TECHNOLOGY Effective use of condensing technology Heating system Return water temp

15. SIMPLIFIED CONDENSING BOILER OPERATION 98 96 Dew Point of Natural Gas 94 92 90 Steady state boiler efficiency % 88 86 Condensing mode Non-Condensing mode 84 82 80 60 80 100 120 140 160 180 200 Boiler returnwater temp of 133

16. How do we get the most from a Condensing Boiler??? Make It RAIN!!! • Condensing Technology. • Rein in the energy savings. Flue gas Flue gas condensing In contact with the Boiler’s heat exchanger Boiler Heat exchanger Latent energy transferred into heating system

17. RETURN WATER TEMPERATURE Boiler return water temperature determines condensing operation

18. 2. Efficiency • Eliminate overheating • Three to one rule • Lower standby losses Outdoor Reset Control • Why use it? • 1. Comfort • Slow space temperature changes • Constant heat output • Keep up vs Catch up

19. Boiler water temperature maintained oF 195 Boiler Water Temperature Traditional boilers must be kept hot 176 On/off control 167 158 140oF Dew point Natural gas 133 Outdoor reset control 117 104 Boiler water temperature modulated 86 72 22 oF +65 +50 32 +14 -4 Outside Temperature HYDRONIC WATER TEMPERATURES

20. oF 194 Condensation range 176 167oF 158 140oF Dewpoint temp 133oF 140 122 System water temperature 104 86 11.3oF 68 14 oF 59 50 41 32 23 5 68 Outside temperature IMPACT OF SYSTEM TEMPERATURES ON CONDENSATION Supply/return temperature: 167/140oF • Fan • Radiators

21. SYSTEM WATER TEMPERATURE DROP What about a higher temperature drop? 30oF……40oF? 140oF 160oF Typical system 20oF Temperature drop 160oF

22. Fan Coils For Condensing Boilers 160OF Air flow 140°F Traditional Fan Coil Sizing 150°F

23. Fan Coils For Condensing Boilers 170OF Air flow 130°F Fan Coil Sizing 150°F

24. INFLUENCING THE RETURN WATER TEMPERATURE Let’s get creative

25. System Supply System Return Condensing boiler Non-Condensing boiler Hybrid System Condensing Boiler

26. Burner type FACTORS INFLUENCING EFFECTIVENESS OF CONDENSING TECHNOLOGY Effective use of condensing technology

27. Natural Gas Combustion +Excess air 10 parts air 1 part gas What happens as we increase excess oxygen to achieve better flame quality? More excess air = Lower CO2% Lower C02% = Lower dew point temperature Lower dew point temp. = Less condensation

28. Turn Down

29. oF 140 131 122 113 104 95 Lower CO2 =Lower Dew point =Less Condensation 86 77 3 5 6 8 9 10 12 2 7 11 4 Natural Gas (95% CH4) • Water vapor condenses below the dew point temperature Higher CO2 =Higher Dew point =More Condensation Dew point water vapor

30. Turn Down Methods High Mass boiler Low Mass High turndown Multiple boilers Single unit multiple gas valves and burners Multiple Gas valves single burner

31. Piping layout FACTORS INFLUENCING EFFECTIVENESS OF CONDENSING TECHNOLOGY Effective use of condensing technology

32. 4-way mixing valve Boiler return water temperature elevation INCORRECT USE OF MIXING VALVES WITHCONDENSING BOILERS 3-way mixing valve Lower boiler return water temperature. CORRECT

33. Low temp system CONDENSING BOILERS IN TWO TEMPERATURE SYSTEMS High temp system

34. COMBINATION OF BOILERS System Supply System Return Boiler Condensing boiler Condensing boiler LAG BOILER LEAD BOILER

35. Integrated solutions for all your hydronic heating and DHW needs Small Boilers Thermal Solar Large Boiler DHW DHW

36. Thank You!!! Terry Stohs Viessmann Manufacturing Company Inc.