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The Evolution Of Radiant Mixing

Explore the importance of mixing for different boiler types in radiant heating systems. Learn about various mixing options, valve types, and piping considerations. Understand system sizing, flow rates, head loss calculations, and resetting techniques for optimal efficiency. Discover the role of 3-way and 4-way valves, climate-based resets, and programming for improved performance. Wiring guidelines, circulator selection, and injection variations are also covered.

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The Evolution Of Radiant Mixing

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  1. The Evolution Of Radiant Mixing How, why and when to mix with a valve

  2. Why Mix? • CI boilers • Need lower temp for radiant • Multi-temp, multi-load • Zone by zone mixing • Mod/Con boilers • Boiler makes hi-temp • Need to mix for lower temp radiant • Zone by zone mixing

  3. Mixing Options • 3-Way tempering valves • Motorized setpoint valves • Motorized reset valves

  4. Mixing Options • 3-Way tempering valve • Fixed water temperature • Simple, thermostatic, non-electric • MUST ZONE radiant system properly/aggressively • Must pipe bypass to protect boiler

  5. Boiler Piping

  6. RadiantReturn 3-Way Tempering Valve Boiler Supply RadiantSupply Boiler Return

  7. 1800 Out Globe Valve Mix Point >1350 1150 Back Protecting The Boiler

  8. A System Sizing Problem

  9. BTUH 30,000 ΔT x 500 10 x 500 A System Sizing Problem • Find the flow rate • GPM = • GPM = • GPM = 6

  10. 1” pipe Sizing The Pipe • 2-4 GPM = ¾” • 4 - 8/9 GPM = 1” • 8-14 GPM = 1¼” • 14-22 GPM = 1½” • Based on maxvelocity of 4 feet per second forcopper 6 GPM = 1” pipe

  11. Flow & Head Loss • Find radiant tube head loss • Measure total run • Multiply by 1.5 • Multiply by .04 • 4’ head/100‘ equiv. length • 60’ x 1.5 = 90 • 90’ x .04 =3.6 feet of head Radiant Tube Head Loss – 5’ 60 feet

  12. What About The 3-Way Valve? • 5’ + 3.6’ = 8.6’ • 1” valve Cv = 3.8 • 3.8 GPM = 1psi • 1psi = 2.31’ head • (Flow 4 Cv)2x 2.31 = head loss • (643.8)2 = 2.5 psi • 2.5 X 2.31 = 5.8’ • 8.6 + 5.8 = 14.4’

  13. iValve Reset • Outdoor reset – more effective, efficient system • Simple wiring – low voltage • Can reset individual zones • Provides boiler protection • Available in 2, 3 and 4-way models

  14. Understanding Reset

  15. Changing Conditions Fixed SWT Variable SWT • Heat loss change every day • Fixed water temp =variable run times = cycling in mild times • Variable water temp =fixed run times =less short cycling =greater efficiency

  16. How Does It Know? • Four key numbers • Outdoor Design Temp • Mix Design • WWSD • Mix Start • Reset ratio = Mix Design Temp - 720 720 – Design Outdoor Temp

  17. = 72 - 0 = 72 Let’s Do One… • Mix Design = 130, Outdoor Design = 0 • 130 – 72 • 58 0.8

  18. What Does 0.8 Mean? • Radiant water temp increases 0.8 of a degree for every 1 degree drop in outdoor temperature • To program: • Move dial on iValve to correct ratio

  19. Cast Iron Boilers • Reset the delivery • Boiler operates on high limit • Requires >1350 to prevent condensing • Boiler fires more effectively, efficiently • Take advantage of thermal mass • Can add boiler reset, as well

  20. Mod/Con Boilers • Multiple water temperature system • Resetting off the reset • Lower return water temps • Greater efficiency

  21. Wiring This Bad Boy… • 3 sensors • Boiler return, radiant supply,outdoor • Outdoor sensor on northside, out of sunlight, abovesnowline • 24v power in • Zoning/circulator controldone externally

  22. 4-Way Valve • One more hole… • Higher Cv • For higher flow rates • ¾” – 7 Cv • 1” – 9.3 Cv • Same wiring • MUST pipe primary-secondary!!!

  23. Piping & Sizing 6 GPM, 5’ head radiant 1” pipe, 10’ total length = 0.6’ head ¾” valve = 1.7’ head Total head = 7.3’

  24. Which Circulator?

  25. Why No 1” Valve? • Could have, but… • 1” valve = 1’ head loss • Same circulator • Why not use less expensive valve? • Smaller valve – tighterwater temp control • Size valve to flow, notline size

  26. 2-Way iValve • Use for “injection” • Higher Cv than 3-way valves • ½” = 4.9 • ¾” = 10.3 • 1” = 8.9 • Can handle higher flowrate applications

  27. Injection “Variation” • Injection without an injection circulator • Bypass, globe valve needed • Size to flow,not line size

  28. 30,00055 x 500 ½” 1” Pipe & Pump Sizing 30,000 BTUH1350 SWT 1250 RWT • 6 GPM, 5’ radiant head loss • Bypass, manifold supplypiping - 1” • Injection pipe sizing: • GPM = • GPM =1.09 • Valve/pipe = ½” • .11 feet of head through valve

  29. Additional Features • Min/max system supply water temperature • Minimum boiler return temperature • Set with dipswitch – 120 or 135 • Disable by not installing boiler return sensor • WWSD -- 70 degrees or off

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