Variable Flow Pumps – Control Strategies

1 Variable Flow Pumps Control Strategies BBT Conference Feb 4/5, 2015. Presented by Steve Thompson VP - Residential Product Management Taco Inc. Mobile (401) 441-2934. E Mail: Variable Flow Pumps Control Strategies Agenda: Introduction General Descriptors VFD or not VFD That is the Question (VFD Assessment Tool). System & Pump Curves Selfsensing Pumps Applications Balancing VFD Pumping Systems Delta T. Warning!!! Efficiency To trim or not to trim ECM Permanent Magnet Technology Affinity Laws Commissioning Tips DOE / ASHRAE / ACEEE. 1. General Descriptors T Differential Temperature Net temperature differential between two points (typically supply and return).

2 20 Deg F Normal differential temperature design for high mass, medium temperature systems 10 to 15 Deg F for radiant 10 to 12 Deg F for chilled water primaries Setpoint Temperature Temperature sensed at single location If sensor built into the pump, the pump must be installed at sensing location Make-up air coil a good example P Differential Pressure Pressure measured or sensed across two points Typical closed loop system pup inlet pressure is relatively constant PC Differential Pressure Constant (flat pump curve). PV Proportional Pressure (inclining pump curve). Self Sensing Pump (Circ) adjusts speed without any physical sensors Reacts to changes in impeller loading as a result of system flow change Primary Circuit Dedicated to moving fluid to/from heating or cooling source Secondary Circuit Supplies fluid to building conditioned space Circulator vs Pump Pumps boost pressure (Well Pumps , Pressure Booster Pumps , Boiler Feed Pumps Circulators invoke fluid movement by overcoming friction loss (could be any Hp).)

3 Residential vs Commercial What's a Variable Flow System Application And Why Does This Matter? An HVAC system is like our body Brain = BMS (BAS) system Heart = pump Stomach = boiler or chiller Arteries = piping system Working out - system under load Body - heart rate up, increased blood pressure, consumes more energy Building more BTU's (flow), more head Sleeping - system under low load or setback Body heart rate and blood pressure down, consumes less energy Building less BTU's, lower head At least that's the way it is supposed to work! What if our heart and blood pressure didn't change? Conclusion all HVAC APPS are Variable flow!

4 2. Start VFD Assessment New Systems Need to vary No duty Consider fixed speed Pumps , On-Off continuously Control , Multiple sizes, etc. Yes VFD potentially useful No Check overall benefits Mostly including non-energy items friction? : reduced maintenance cost Yes VFD potentially useful Calculate total annual operating cost with alternative system solutions Does the pump No run most of the No Use fixed time? Is VFD suitable? speed Viridian Yes Yes VFD almost certainly beneficial Use VFD. Start VFD Assessment Retrofit Systems No Confirm existing fixed No Is duty Consider modification or speed pump is Variable replacement of equipment correctly sized Yes Yes Retain existing VFD potentially useful installation if efficient Check overall benefits No including non-energy items Mostly : reduced maintenance cost friction?

5 Yes Calculate total annual operating cost with alternative VFD potentially useful system solutions Yes Is VFD No Does the pump No suitable? run most of the time? Are existing pump and No Yes motor suitable for proposed VFD. VFD almost certainly beneficial Yes VFD. 3. System Curves 3-Way Control Valve 60 GPM each fan coil Design Operating Point 300 Gallons Per Minute 53 Feet of Head 150 ton system @ 12deg Delta T. System Curves System Capacity Design Operating Point Head (H) in (Q) in Feet GPM. 0. 7. 25. 53. 90. 136. 4. System Curves Pump Curves Pump Curve 70. KS Model 4009. Test Data at 1760 RPM 60. " Diameter 50. Head (H) in Feet Capacity Head Efficienc BHP.

6 (GPM) (Ft) y (%) (HP) 40. 30. 20. 10. 0. 0 100 200 300 400 500. Flow (Q) in GPM. 5. System Curves 3-Way Control Valve Pump Curves This image cannot currently be display ed. KS Model 4009. With an impeller Test Data at 1760 RPM. Pump System Capacity Efficiency BHP Head Head (Ft). (GPM) (%) (HP) (Ft). 0. 6. SelfSensing Pumps Variable Loads (Zones Closing). 3-Way Valve SelfSensing Pumps Valves Closed Valves Open Minimum Flow Maximum Flow 100. 90. 80. 70. Head (Ft.). 60. 50. 40. 30. 20. 10. 0. 0 50 100 150 200 250 300 350 400 450. Flow (GPM). 7. SelfSensing Pumps Valves Closed Valves Open 100. Minimum Flow Maximum Flow 90.

7 80. 70. 60. Head (Ft.). 50. 40 60 Hz 30. 50 Hz 40 Hz 20. 30 Hz 10. 20 Hz 0. 0 50 100 150 200 250 300 350 400 450. Flow (GPM). SelfSensing Pumps Valves Closed Valves Open 100. Minimum Flow Maximum Flow 90. 80. 70. 60. Head (Ft.). 50. 60 Hz Control Curve 40. 30. 20. 20 Hz 10. 0. 0 50 100 150 200 250 300 350 400 450. Flow (GPM). 8. Integrated VFD with Sensorless Control Constant Pressure Mode Proportional Pressure Mode True System Curve Mode Applications Example: Chilled water primary / secondary system 9. Constant Flow Mode Self-sensing CONSTANT flow is self-balancing and automatically adjusts flow to maintain user-defined flow set point.

8 Used on constant flow chiller / boiler Pumps Benefits: Balancing through reduced speed not false head Reduced speed increases equipment life Balancing done internally and automatically Auto adjust over the life and fouling of the system Using full trim impellers Allows for design reality differences Variable Flow Mode Self-sensing Variable flow adapts to system pressure variations and automatically follows the system performance curve to meet demand. Used on secondary Variable speed Pumps Benefits: Lower install costs No error in setpoint Improved system efficiency and performance Reduced coordination and construction schedule 10.

9 Variable flow Direct Return Piping System Constant flow (first in / first out). Balancing complexity - high TERMINAL UNITS. HYDRONIC VALVE Control . VALVE. MULTIPURPOSE. VALVE BALANCE. HIGH EFFICIENCY VALVE. AIR & DIRT SEPERATOR SUPPLY PIPE. SUCTION TACO VERTICAL. DIFFUSER INLINE PUMP. RETURN PIPE. EXPANSION BOILER. TANK. Variable flow Reverse Return Piping System Constant flow (first in / last out). Balancing complexity low TERMINAL UNITS. Self Balancing HYDRONIC VALVE Control . VALVE. MULTIPURPOSE. VALVE BALANCE. HIGH EFFICIENCY VALVE. AIR & DIRT SEPERATOR SUPPLY PIPE. RETURN PIPE. SUCTION TACO VERTICAL. DIFFUSER INLINE PUMP.

10 EXPANSION BOILER. TANK. 11. Variable flow Primary Secondary Systems Constant flow (pumped secondary). Balancing complexity depends TERMINAL UNITS. HYDRONIC VALVE Control . VALVE. MULTIPURPOSE. VALVE BALANCE. HIGH EFFICIENCY SUPPLY PIPE VALVE. AIR & DIRT SEPERATOR. CROSSOVER. BRIDGE. SUCTION TACO VERTICAL. DIFFUSER INLINE PUMP. RETURN PIPE. EXPANSION BOILER. TANK. Variable flow . Constant flow Injection Pumping System Balancing complexity TERMINAL UNITS. Crossover bridges balance Which circs Variable flow? CIRCULATING. PUMP. INJECTION. PUMP. BALANCE. MULTIPURPOSE SUPPLY PIPE VALVE. HIGH EFFICIENCY VALVE. AIR & DIRT SEPERATOR RETURN PIPE.