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The Evolution Of Radiant Mixing

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

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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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