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Hydronic Basics / Primary-Secondary Pumping

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Dan Watkins from Bornquist presents Hydronic Basics and Primary-Secondary Pumping Systems.

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Hydronic Basics / Primary-Secondary Pumping

  1. 1. Hydronic System Piping Design Presented by: Dan Watkins, LEED AP Bornquist, Inc.
  2. 2. Topics to Cover <ul><li>Hydronic System Basics </li></ul><ul><li>Hydronic System Types </li></ul><ul><li>Primary – Secondary </li></ul><ul><li>Variable Flow / Variable Speed Systems </li></ul><ul><li>Piping Design Examples </li></ul>
  3. 3. Hydronic System Basics SOURCE LOAD In a Hydronic System
  4. 4. Hydronic System Basics SOURCE LOAD Source & Load connected by piping
  5. 5. Hydronic System Basics SOURCE LOAD Fluid is circulated by a pump
  6. 6. Hydronic System Basics <ul><li>Could it really be this simple? </li></ul><ul><li>What about different system types? </li></ul><ul><li>What about multiple zones? </li></ul><ul><li>Let’s start with how to size a pump. </li></ul>
  7. 7. Hydronic System Basics <ul><li>To size a pump you need to know required flow rate for the system and piping pressure drop. </li></ul><ul><li>Flow rate is based on amount of heat to be transferred. </li></ul><ul><ul><li>BTUh = 500 x Δ T x GPM </li></ul></ul><ul><ul><li>ΔT is the temperature drop desired in the system. </li></ul></ul><ul><ul><li>BTUh is the amount of heat to be transferred. </li></ul></ul><ul><li>Pressure drop is based on the flow rate through a given piping system. </li></ul>
  8. 8. Hydronic System Basics Let’s design a simple system together! Boiler 200,000 BTUh AHU Coil 20 GPM Boiler = 5’ TDH AHU = 10’ TDH Piping = ???
  9. 9. Hydronic System Basics Let’s design a simple system together! Rule of Thumb… Length x 1.5 to account for elbows and fittings. 2.94’ per 100’ of piping 100’ x 1.5 = 150’ 1.5 x 2.94’ = 4.41’ TDH
  10. 10. Hydronic System Basics Let’s design a simple system together! Boiler 200,000 BTUh AHU Coil 20 GPM Boiler = 5’ TDH AHU = 10’ TDH Piping = 4.41’ TDH System Capacity: 20 GPM @ 19.41’
  11. 11. Hydronic System Basics
  12. 12. Hydronic System Basics GPM 2 GPM 1 HEAD 2 RPM 2 RPM 1 HEAD 1 HP 2 HP 1 RPM 2 RPM 1 RPM 2 RPM 1 HP 2 HP 1 GPM 2 GPM 1 GPM 2 GPM 1 HEAD 2 HEAD 1 Affinity Laws 2 2 3 3 = = = = =
  13. 13. Hydronic System Basics <ul><li>Point of No Pressure Change – Expansion Tank Location </li></ul>
  14. 14. Hydronic System Basics <ul><li>Expansion Tank at Suction of Pump - Correct </li></ul>
  15. 15. Hydronic System Basics <ul><li>Expansion Tank at Discharge of Pump - INCORRECT </li></ul>
  16. 16. Hydronic System Basics NPSHA & NPSHR P NPSHA P B Foot Check - (FC) h L Strainer - (S) P P P NPSHA = (+P B ) + (-FC) + (-h L ) + (-P P ) + (-S) Pipe Pressure Drop
  17. 17. Hydronic System Basics P NPSHA P B Foot Check - (FC) 10’ Strainer - (S) 8’ P NPSHA = (+P B ) + (-FC) + (-h L ) + (-P P ) + (-S) Pipe Pressure Drop P B - 14.7 PSI (34’) P NPSHA = (+34) + (-4) + (-10) + (-8) + (-3) P NPSHA = 9’ NPSHA & NPSHR - Suction Lift
  18. 18. Hydronic System Basics NPSHA & NPSHR - Flooded Suction P NPSHA 8’ Pipe Pressure Drop P B - 14.7 PSI (34’) Strainer - (S) 10’ P B P NPSHA = (+P B ) + (-FC) + (-h L ) + (-P P ) + (-S) P NPSHA = (+34) + (-4) + (+10) + (-8) + (-3) P NPSHA = 29’
  19. 19. Total system HEAD & FLOW requirements through two parallel pumps Total System Head 1/2 Total Flow 1/2 Total Flow Hydronic System Basics Parallel Pumps
  20. 20. Two pumps in operation Each pump Head (ft) Flow (gpm) Hydronic System Basics Parallel Pumps
  21. 21. Total system HEAD & FLOW requirements through two series pumps Total System Flow 1/2 Total Head 1/2 Total Head Hydronic System Basics Series Pumps
  22. 22. Hydronic System Design Flow (gpm) Two pumps in operation Each pump Head (ft) Series Pumps
  23. 23. Hydronic System Types <ul><li>Open Loop System </li></ul>
  24. 24. Hydronic System Types Closed Loop System
  25. 25. Hydronic System Types Direct Return System
  26. 26. Hydronic System Types Reverse Return System
  27. 27. Primary – Secondary Piping <ul><li>Primary – Secondary Pumping: Was developed by Bell & Gossett in 1954 as a method to increase system temperature drops, decrease total pump Horse Power and increase system controllability. Systems utilizing low or medium temperatures were allowed due to Primary – Secondary pumping. Most modern systems utilize some variation of Primary – Secondary pumps. </li></ul>
  28. 28. Primary – Secondary Piping <ul><li>“ Common Piping” interconnects the Primary to the Secondary Circuit </li></ul><ul><li>“ Common Piping” should have minimal to no pressure drop to be designed correctly </li></ul><ul><li>Hydraulically disconnects the two piping loops </li></ul><ul><li>Flow in one loop will not cause flow in the other loop </li></ul>
  29. 29. Primary – Secondary Piping Basic Example
  30. 30. Primary – Secondary Piping Flow in the Common Pipe
  31. 31. Primary – Secondary Piping Finite Analysis of Common Piping Primary Return Secondary Return Secondary Supply Primary Supply
  32. 32. Primary – Secondary Piping Law of the Tees
  33. 33. Primary – Secondary Piping <ul><li>Secondary pipe pump sized for pressure drops A-B, B-C, C-D, D-E, E-G, G-H, H-I </li></ul><ul><li>I-A should have no pressure drop. </li></ul>
  34. 34. Primary – Secondary Piping Cross-over Bridge Piping - Underslung
  35. 35. Primary – Secondary Piping Cross-over Bridge Piping - Overhead
  36. 36. Primary – Secondary Piping Correct Pump Location
  37. 37. Primary – Secondary Piping INCORRECT Pump Location
  38. 38. Primary – Secondary Piping What is the Flow Rate in the Common Pipe?
  39. 39. Primary – Secondary Piping What is the Flow Rate in the Common Pipe?
  40. 40. Primary – Secondary Piping Injection Pump Systems
  41. 41. Primary – Secondary Piping 3-Way Valve Systems
  42. 42. Primary – Secondary Piping 2-Way Valve Systems
  43. 43. Primary – Secondary Piping Fixed Temperature Control
  44. 44. Primary – Secondary Piping Modulating Temperature Control
  45. 45. Primary – Secondary Piping Modulating Temperature Control
  46. 46. Variable Flow / Variable Speed
  47. 47. Variable Flow Systems <ul><li>Constant Speed / Variable Volume </li></ul><ul><ul><li>Utilizes 2-way valves </li></ul></ul><ul><ul><li>Pump Energy is reduced </li></ul></ul><ul><li>Variable Speed / Variable Volume </li></ul><ul><ul><li>Utilizes 2-way valves </li></ul></ul><ul><ul><li>Pump Energy is reduced </li></ul></ul><ul><ul><li>Uses VFDs to reduce pump speed </li></ul></ul>
  48. 48. Variable Flow Systems Constant Flow System
  49. 49. Variable Flow Systems Constant Speed - Variable Flow System
  50. 50. Variable Flow Systems Variable Volume System HP
  51. 51. Variable Flow Systems <ul><li>Variable Speed gives reduced HP </li></ul><ul><li>Variable Speed allows for easy pump balancing </li></ul><ul><li>Variable Speed also acts as a soft starter </li></ul><ul><li>Variable Speed drives are getting less costly </li></ul><ul><li>Variable Speed is not a mystery anymore </li></ul>
  52. 52. Hydronic System Basics GPM 2 GPM 1 HEAD 2 RPM 2 RPM 1 HEAD 1 HP 2 HP 1 RPM 2 RPM 1 RPM 2 RPM 1 HP 2 HP 1 GPM 2 GPM 1 GPM 2 GPM 1 HEAD 2 HEAD 1 Affinity Laws 2 2 3 3 = = = = =
  53. 53. Variable Flow Systems 12.5HP 1800 RPM 1.6HP 950 RPM HP 2 12.5 = 900 1800 3 HP 1 = 1.6 HP
  54. 54. Variable Flow Systems
  55. 55. Variable Flow Systems
  56. 56. Variable Flow Systems SOURCE SOURCE System Criteria 2 - 100 Ton Chillers 2 - 300 GPM @ 100’ Pumps Pumps 2 - 20HP No Standby System Pressure Drop Total of 75’  P Chiller Pressure Drop Total of 25’  P TOTAL INSTALLED HP - 40 HP LIMITED VARIABLE VOLUME - 30% MAX HP REDUCTION
  57. 57. Variable Flow Systems SOURCE SOURCE System Criteria 2 - 100 Ton Chillers 2 - 300 GPM @ 25’ Pumps 2 - 300 GPM @ 80’ Pumps Primary Pumps 2 - 3HP Secondary Pressure Drop Total of 80’  P Primary Pressure Drop Total of 25’  P Secondary Pumps 2 - 10 HP Running Standby TOTAL INSTALLED HP - 26 HP 2 - 10 HP VFDs w/ STAGING REQ’D
  58. 58. Variable Flow Systems DP Sensor Location – Sensor Across Coil Typical Setting Equals Design Pressure Drop Across the Coil, Control Valve, and Circuit Setter. Coil 10 - 15’ P.D. Control Valve 10 - 15’ P.D. Typical Total P.D. 20 -30’
  59. 59. Variable Flow Systems DP Sensor Location – INCORRECT
  60. 60. Variable Flow Systems DP Sensor Location – INCORRECT
  61. 61. Variable Flow Systems DP Sensor Location – Correct
  62. 62. Variable Flow Systems DP Sensor Location – Correct
  63. 63. System Examples Chilled Water – Direct Return with Variable Speed
  64. 64. System Examples Chilled Water – Reverse Return with Variable Speed
  65. 65. System Examples Boiler Water – Direct Return with Variable Speed
  66. 66. System Examples Boiler Water – Reverse Return with Variable Speed
  67. 67. System Examples Primary – Secondary - Tertiary
  68. 68. System Examples Primary – Secondary Zone Pumping
  69. 69. System Examples Campus / District – Primary – Secondary - Tertiary
  70. 70. Special System Piping
  71. 71. Chilled Water Piping Examples
  72. 72. Tenant Use Pumps Tower Condenser Tenant Unit Tenant Unit Main Building Chiller
  73. 73. Tenant Use Pumps PDt Main Building Chiller Hst Ht PDrp PDsp PDs PDpt PDc PDt - Tower Pressure Drop PDsp - Suction Pipe Pressure Drop PDs - Strainer Pressure Drop PDpt - Pump Trim Pressure Drop PDc - Condenser Pressure Drop PDrp - Return Pipe Pressure Drop Ht - Tower Height - Static Lift Hst - Building Static Height Condenser
  74. 74. Tenant Use Pumps PDt - 15’ Main Building Chiller Hst - 100’ Ht - 10’ PDrp - 8’ PDsp - 8’ PDs - 3’ PDpt - 6’ PDc - 25’ ONLY STATIC PRESSURE SEEN AT PRESSURE GAUGE ON SUCTION OF PUMP P1 - 43 PSI Pump OFF Condenser P1 P2
  75. 75. Tenant Use Pumps PDt - 15’ Main Building Chiller Hst - 100’ Ht - 10’ PDrp - 8’ PDsp - 8’ PDs - 3’ PDpt - 6’ PDc - 25’ SUCTION SIDE OF PUMP - STATIC PRESSURE MINUS PDsp. AND MINUS PDs P1 >> 100’ - 8’ - 3’ = 38.5 PSI DISCHARGE SIDE OF PUMP - SUCTION PRESSURE PLUS PUMP HEAD (75’) P2 >> 38.5 PSI + 75’ = 71 PSI Pump On Pump Head = PDsp + PDs + PDpt + PDc + PDrp + Ht + PDt Condenser P1 P2
  76. 76. Tenant Use Pumps PDt Main Building Chiller Hst Ht PDrpa PDspa PDs PDpt PDc Ht - Tower Height - Static Lift Hst - Building Static Height PDspb PDrpb Hsta Hstb PDtenant PDt - Tower Pressure Drop PDspa - Suction Pipe Pressure Drop a Length PDspb - Suction Pipe Pressure Drop b Length PDs - Strainer Pressure Drop PDpt - Pump Trim Pressure Drop PDc - Condenser Pressure Drop PDrpa - Return Pipe Pressure Drop a Length PDrp b- Return Pipe Pressure Drop b Length Pdtenant - Tenant Loop Total Pressure Drop Condenser Tenant Unit
  77. 77. Tenant Use Pumps PDt - 15’ Main Building Chiller Hst - 100’ Ht - 10’ Pdrpa - 6’ Pdspa - 6’ PDs - 3’ PDpt - 6’ PDc - 25’ PDspb - 2’ PDrpb - 2’ Hsta - 80’ Hstb - 20’ Pdtenant - 25’ Tenant Pump Off - Main Pump On P3 - STATIC PRESSURE A MINUS PDspa. P3 >> 80’ - 6’ = 32 PSI P4 - DISCHARGE SIDE OF PUMP - SUCTION PRESSURE PLUS PUMP HEAD (75’) MINUS PRESSURE DROPS P4 >> 71PSI - 6’ - 25’ - 20’ - 2’ = 48PSI Difference P3 - P4 = 16 PSI (37’) Condenser Tenant Unit P3 P4
  78. 78. Tenant Use Pumps PDt - 15’ Main Building Chiller Hst - 100’ Ht - 10’ Pdrpa - 6’ Pdspa - 6’ PDs - 3’ PDpt - 6’ PDc - 25’ PDspb - 2’ PDrpb - 2’ Hsta - 80’ Hstb - 20’ Pdtenant - 25’ <ul><li>Tenant Pump Sized for: </li></ul><ul><ul><li>Piping Pressure Drop </li></ul></ul><ul><ul><li>Pump Trim Pressure Drop </li></ul></ul><ul><ul><li>Tenant Unit Pressure Drop </li></ul></ul><ul><ul><li>P4 - P3 Differential </li></ul></ul>Tennant Pump Head = Pdtenant + 37’ = 25’ + 37’ = 62’ Condenser Tenant Unit P3 P4
  79. 79. Tenant Use Pumps Tenant Use Pumps Must be with the rest of the condenser water pumping system in mind. Never size a tenant use system, for only the tenant loop pressure drop. Typical Pump Size 15 GPM @ 100’ TDH Tower Condenser Tenant Unit Tenant Unit Main Building Chiller
  80. 80. Chiller Water Piping Examples
  81. 81. Chiller Water Piping Examples
  82. 82. Chiller Water Piping Examples
  83. 83. Chiller Water Piping Examples
  84. 84. Chiller Water Piping Examples
  85. 85. Chiller Water Piping Examples
  86. 86. Chiller Water Piping Examples
  87. 87. Boiler Piping Examples
  88. 88. Boiler Piping Examples
  89. 89. Boiler Piping Examples
  90. 90. Boiler Piping Examples
  91. 91. Boiler Piping Examples
  92. 92. Boiler Piping Examples
  93. 93. Boiler Piping Examples
  94. 94. Boiler Piping Examples
  95. 95. Boiler Piping Examples
  96. 96. Boiler Piping Examples
  97. 97. Boiler Piping Examples
  98. 99. Hybrid Boiler System
  99. 100. Boiler Piping Examples
  100. 101. Conclusions <ul><li>Hydronic Systems require a lot of considerations. </li></ul><ul><li>Primary – Secondary is only one of many ways to design, but is still a widely used design strategy. </li></ul><ul><li>Variable – Primary systems can work, but need special considerations to prevent equipment problems. </li></ul><ul><li>Variable Flow / Variable Speed systems have become the standard, but also require special considerations. </li></ul><ul><li>System piping must be designed to satisfy the requirements of the building and installed equipment. No “One-Size-Fits-All” Solution. </li></ul>
  101. 102. Questions???
  102. 103. Thanks!

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