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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