Variable Volume Chilled Water Pumping System Control

Only available on StudyMode
  • Topic: Valve, Pump, Plumbing
  • Pages : 10 (2548 words )
  • Download(s) : 25
  • Published : April 2, 2013
Open Document
Text Preview
Variable Volume Chilled Water Pumping System Controls
Dave Hacker – Engineering Manager Kyle Schroeder, PE – Sales Engineer

Outline
• Introduction • Chilled Water Pumping Systems Configurations / Control Strategies – Primary – Secondary Pumping – Variable Primary Pumping

• Demonstration / Live Web Graphics • Discussion and Questions

Local Service and Support Innovative Energy Solutions
• 45 year record of successful project installations
– Hundreds of local DDC installations

• On-staff engineers, technicians
– Factory-trained

• 24 hour 7 day on-call service for Temperature Controls and Full HVAC Mechanical Service • Service agreements • Comprehensive local parts stock • Local training • Over 250 years HVAC / Controls experience on staff

Evolution of Pumping Systems

y log hno Tec e Curv
Constant Speed Systems

VFDs
1990s

hiller ow C le Fl ariab V
2000s

Pump

1980s

In n ova Primar y / Sec tion on

3-wa y val ves

ndary Bypa ss V alves

Basic Chilled Water Pumping System

Basic Chilled Water Pumping System
• Single Chiller, Single Constant Speed Pump • 3-way valves for all Chilled Water Coils ( ) maintains constant flow. • Control strategy: Enable chilled water pump when outside air temperature is above setpoint and at least 1 chilled water coil control valve is open to coil. Enable chiller after flow is proven. Chiller operates to maintain leaving chilled water temperature at setpoint. Coil valves modulate to maintain comfortable space conditions. or even more basic – no valves – full flow

Basic Primary / Secondary Chilled Water Pumping System with a 3-way valve

Basic Primary / Secondary Chilled Water Pumping System
• • • • Single Chiller, Single Constant Speed Primary Pump, bypass loop with no valve, Variable Speed Secondary Pump. The primary pump pumps water through the chiller. The secondary pump pulls water from the primary system and pumps it to the coils. Add a Water Differential Pressure Transmitter near the end of the piping run (in an accessible location). VFDs and pumps have minimum recommended operating speeds, typically about 20%. Use 3-way valves for 1 or more coils to ensure that there is always this amount of water flowing in the secondary loop. My recommendation is to use 3-way valves at units that are expected to have full occupancy for the most hours and not at Gymnasium or other units that serve areas where significant operating time is at less than full occupancy (partial / low load areas). Control strategy: Enable both primary and secondary chilled water pumps when outside air temperature is above setpoint and at least 1 chilled water coil control valve is open to coil. Modulate (vary) the speed of the secondary pump VFD to maintain a constant differential pressure. Enable chiller after flow is proven. Chiller operates to maintain leaving chilled water temperature at setpoint. Coil valves modulate to maintain comfortable space conditions.



Primary / Secondary Chilled Water Pumping System with Bypass Valve

Primary / Secondary Chilled Water Pumping System with Bypass Valve • • • • • Single Chiller, Single Constant Speed Primary Pump, bypass loop, Variable Speed Secondary Pump. 2-way valves at all chilled water coils and secondary bypass loop with 2-way valve. The primary pump pumps water through the chiller. The secondary pump pulls water from the primary system and pumps it to the coils. Water Differential Pressure Transmitter near the end of the piping run. VFDs and pumps have minimum recommended operating speeds, typically about 20%. Use a bypass valve in the secondary loop. My recommendation is to locate the valve in the chiller mechanical room. Control strategy: Enable both primary and secondary chilled water pumps when outside air temperature is above setpoint and at least 1 chilled water coil control valve is open to coil. Modulate (vary) the speed of the secondary pump VFD to maintain a constant differential pressure....
tracking img