FLOW THINKING COMMERCIAL BUILDING SERVICES Approaching Flow = Load % Load Time
Any Questions? Alternate Pumping Methods Comparison
FLOW THINKING COMMERCIAL BUILDING SERVICES Two Pipe Direct Return
FLOW THINKING COMMERCIAL BUILDING SERVICES Two Pipe Reverse Return
FLOW THINKING COMMERCIAL BUILDING SERVICES Primary-Secondary Pumping. • Simplest to install. • Simplest to operate. • Flexible in design for present and future. • Efficient to operate. • May over-pressurize near zones.
FLOW THINKING COMMERCIAL BUILDING SERVICES Primary-Secondary-Tertiary
FLOW THINKING COMMERCIAL BUILDING SERVICES Primary-Secondary-Tertiary Pumping. • Best piping flexibility. • Best expansion flexibility. • Provides hydraulic decoupling. • Efficient to operate. • May require added horsepower. • Requires additional pumps and piping. • Increased controls complexity.
FLOW THINKING COMMERCIAL BUILDING SERVICES Primary-Secondary-Tertiary Hybrid
FLOW THINKING COMMERCIAL BUILDING SERVICES Primary-Secondary-Tertiary Hybrid Pumping. • Low present horsepower. • Low future horsepower. • Good piping flexibility. • Good expansion flexibility. • Provides hydraulic decoupling. • May require added horsepower • Requires additional pumps and piping. • Increased controls complexity.
FLOW THINKING COMMERCIAL BUILDING SERVICES Primary-Secondary Zone Pumping
FLOW THINKING COMMERCIAL BUILDING SERVICES Primary-Secondary Zone Pumping. • Low ‘built out’ horsepower. • Low system head. • Increased control complexity. • Present horsepower total higher due to future needs. • Present pumps sized for future requirements. • Difficult to apply in retrofits projects.
Any Questions?
Variable Volume Variable Speed
FLOW THINKING COMMERCIAL BUILDING SERVICES Why Do We Need Variable Speed Secondary Pumps ??? •For Energy Saving…. •For better & optimise operation….
FLOW THINKING COMMERCIAL BUILDING SERVICES How Do We Achieve This Reduction In Power Consumption ?? By Using Variable Frequency Drive and Logic controller with the Secondary Pumps….
FLOW THINKING COMMERCIAL BUILDING SERVICES Power Comparison at Reduced Speed
FLOW THINKING COMMERCIAL BUILDING SERVICES Basic Law which helps in achieving this – Affinity law 1. Flow 2 = Flow 1 (Speed 2 / Speed 1 ) 2. Head 2 = Head 1 (Speed 2 / Speed 1 ) 2 3. BKW 2 = BKW 1 (Speed 2 / Speed 1 ) 3 If Diameter of Impeller is to be trimmed then instead of speed the same can be used in above formulas.
FLOW THINKING COMMERCIAL BUILDING SERVICES Operating Cost 450 400 350 Annual Operating Cost $1000 300 250 $0.10/kWh 200 150 100 50 0 50 100 150 200 250 300 350 400 450 500 Motor Horsepower
FLOW THINKING COMMERCIAL BUILDING SERVICES Variable flow system System Curve as two way valves close Pump Curve Head System Curve Flow
FLOW THINKING COMMERCIAL BUILDING SERVICES Energy savings offset System Curve at part load System Curve Pump at design flow Curve Increased head loss H Q
FLOW THINKING COMMERCIAL BUILDING SERVICES Pumps in parallel System Curve Head Pumps in Parallel Single Pump Flow
FLOW THINKING COMMERCIAL BUILDING SERVICES Parallel pumping power savings 100 Single Large Pump 90 80 Horsepower 70 Two Parallel % 60 Pumps 50 40 30 Single Parallel 20 Pump 10 00 10 20 30 40 50 60 70 80 90 100 Flow %
FLOW THINKING COMMERCIAL BUILDING SERVICES Theoretical Savings
FLOW THINKING COMMERCIAL BUILDING SERVICES Establishing Efficiency Curves 50 % 60 % ��� 70 % % Efficiency 80 % 85 % 85 % ��� 80 % ��� 100 % �� �� 90 % Head, Feet �� % Speed Curves 80 % �� Constant �� Efficiency 70 % Curve �� 60 % �� 50% �� 40 % �� 30 % GPM � � ��� ��� ��� ��� ��� ��� ��� ��� ��� ����
FLOW THINKING COMMERCIAL BUILDING SERVICES Variable Speed Efficiencies 4500 gpm @ 100 FT, 85.9 % A 900 1150 600 1450 1770 B 1770 C E 1450 D 1150 900 750 600
FLOW THINKING COMMERCIAL BUILDING SERVICES “No Valve” System Curve 110 25 FT Differential Head Maintained Across Load 100 (Set Point) Set Point 80 Head Pump TDH 60 Overall 40 system curve Distribution piping head 20 loss curve 0 0 200 400 600 800 1000 1200 1400 1600 Flow
FLOW THINKING COMMERCIAL BUILDING SERVICES Effect of Constant Set Point 110 100 Set point, Control curve 25 FT 80 Head Pump TDH 60 Overall system curve 40 Distribution piping head 20 loss curve 0 0 200 400 600 800 1000 1200 1400 1600 Flow
FLOW THINKING COMMERCIAL BUILDING SERVICES Control curve P1 P2 100% Control Curve 75% 50% Head Variable Head ∆ P Loss Flow
FLOW THINKING COMMERCIAL BUILDING SERVICES Large systems, long pipe runs Single C/S Pump, 200% Overheaded 50 45 Annual 40 Operating 35 Cost Single C/S Pump, No Overheading 30 ($1000/year 25 @ $0.10/kwh) 20 15 p m u 10 P d e e p S e l b a i r a V 05 00 1000 2000 3000 4000 5000 Total Equivalent Pipe Length (feet)
FLOW THINKING COMMERCIAL BUILDING SERVICES Variable Head Loss Ratio C/S, Constant Flow System Pump Head Matched to 100 System at Design Flow Base 90 80 C/S, Variable Flow Percent Design BHP 70 V/S, 0% Variable Hd Loss, 100% Constant ∆ Hd 60 V/S, 25% Variable Hd Loss, 75% Constant ∆ Hd 50 40 V/S, 50% Variable Hd Loss, 50% Constant ∆ Hd 30 V/S, 75% Variable Hd Loss, 25% Constant ∆ Hd 20 V/S, 100% Variable Hd Loss, 0% Constant ∆ Hd 10 0 % Flow 10 20 30 40 50 60 70 80 90 100
FLOW THINKING COMMERCIAL BUILDING SERVICES Variable Head Ratio w/ Overheading Constant Flow, C/S Pump Pump O’Headed by 150% 150 (3 Way Valve) 140 C/S Pump 130 (2 Way Valve) 120 110 Base Constant Flow, C/S Pump Pump HD Matched 100 Design to System @ (3 Way Valve) Design Flow 90 HP % ) e v l a V 80 y a W V/S, 100% Constant HD 2 ( 70 p m u P S 60 / C % Full Load 50 V/S, 25/75* * 25/75 Means: (Design) HP V/S, 100% Variable HD 40 V/S, 50/50 25 % Variable HD Loss 75 % Constant HD Loss 30 V/S, 75/25 20 10 0 10 20 30 40 50 60 70 80 90 100
FLOW THINKING COMMERCIAL BUILDING SERVICES Locations of Sensor Where to install the Sensor? What type of Sensor?
FLOW THINKING COMMERCIAL BUILDING SERVICES Single Point Pressure Sensor Load Balancing Valve 2 – Way Valve Single Point Pressure Sensing Chillers Panel with PLC & VFD`s Common Secondary Pumps Primary Pumps Air - Separator
FLOW THINKING COMMERCIAL BUILDING SERVICES Single Point Pressure Sensor Is Single Point Pressure Sensor Correct? Wrong !! Why? -Pump is a differential pressure device. -A single point is only influence by pressure. This is good for booster only. -In a closed loop system, system pressure rises due to thermal expansion, pumps will slow down. -When static pressure decrease, pumps will speed up. -This is self-defeating since now the pump speed is not influence by the system load changes, but rather by system water pressure. -Therefore, single pressure sensor are a misapplication in a closed loop HVAC system.
FLOW THINKING COMMERCIAL BUILDING SERVICES Single Point Differential Pressure Sensor Primary - Secondary Circuit With Variable Speed Secondary Pumps Load Balancing Valve 2 – Way DPT Valve Chillers Panel with PLC & VFD`s Common Secondary Pumps Primary Pumps Air - Separator
FLOW THINKING COMMERCIAL BUILDING SERVICES 2 Way Valve Control Opening/Closing of 2- Way Valve -Signal from the sensor, installed at load regulates the valve opening & closing. -This way differential across 2-way valve also changes & accordingly output signal is given to PLC. Temperature Sensor Load ` ` Output to PFU from DPT `
Question: Can we put the DPT across coil alone?
Question: Across the pumps?
FLOW THINKING COMMERCIAL BUILDING SERVICES Single Point Differential Pressure Sensor Primary - Secondary Circuit With Variable Speed Secondary Pumps To Maximize energy system, we must maximize the variable head loss in the system. This is done by locating the sensor at the most remote zone ( hydraulically) in the system.
FLOW THINKING COMMERCIAL BUILDING SERVICES System Control Curve 110 100 Set point, 25 FT 80 Ft Hd Control curve Pump TDH 60 Overall 40 system curve Distribution piping head 20 loss curve 0 0 200 400 600 800 1000 1200 1400 1600 Flow, gpm
FLOW THINKING COMMERCIAL BUILDING SERVICES Variable vs Constant Head Loss
FLOW THINKING COMMERCIAL BUILDING SERVICES The “Active Zone” • Zone set points do not have to be the same. • Pump controller scans all zones often, comparing process variable to set point in each case. • Pumps are controlled to satisfy the worst case. • What happens to the rest of the zones?
FLOW THINKING COMMERCIAL BUILDING SERVICES Basic Concept Set Value PMU Output 4 – 20 mA To PFU From Field VFD/Pump Sensor (DPT) PFU – Pump Functional Unit PMU – Pump Management Unit
FLOW THINKING COMMERCIAL BUILDING SERVICES Multi Point Differential Pressure Sensor Different Sensor Signal To Common PFU Panel DPT DPT Balancing Valve Load Panel with PLC & VFD`s Secondary Chillers Pumps Common
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