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The State of the HVAC Industry. Escalating energy and electrical power costsTime-of-day pricing, kW demand charges for transmission
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2. The State of the HVAC Industry Escalating energy and electrical power costs
Time-of-day pricing, kW demand charges for transmission & generation
Variable speed pumping standard (ASHRAE 102)
Single pumps have higher head than staged systems
Phased building construction
Over-powered physical plant for sections completed first
Can have poor control, non-warranty product failures
LEED makes designers responsible for building performance
Zoning most effective with hydronics
Intense focus on reduced resource needs
Sophisticated designs with higher capital cost
Industry strapped for time/people
Non-traditional hydronic geographies (e.g.: sunbelt States)
Growing skills gap
Untrained installers, inexperienced designers
Need to mistake-proof system design and commissioning
Water quality more important than ever
3. Benefits of Pressure-Independent Control Pressure-regulated valves enable:
20% up to 50% energy savings reported in industry case studies
Smaller chillers and pumps
Reduced capital cost
Reduced energy consumption
Reduced electrical demand
Dynamically self-balanced loops
All load conditions
Smaller piping, direct connection
In retrofit: increased chiller capacity in existing systems
4. Traditional Hydronic HVAC System Design Large or multiple chillers/boilers
Operated inefficiently at low ?T, except at design loads
Large, high flow pump stations
Large supply and return risers
Static balancing valves (mechanical Division)
Automatic control valves (HVAC Division)
3-way valves at end of loops for pressure relief, flow maintenance
5. Modern Hydronic HVAC System Design Smaller/fewer chillers/condensing boilers
Operated efficiently at high ?T under all load conditions
Smaller, high pressure, variable speed pump stations
Smaller supply and return risers
Balancing valves integrated with Automatic control valves
Pressure-independent control
6. Traditional HVAC Flow Balancing Limit flow to calculated design when every branch of the HVAC system is “wide open”
Prevents closest branches from starving far loops
Standard solution: multi-turn manual balancing valves
Hard to achieve well-balanced system with traditional products and methodology
3 passes around the building to adjust balancing valves in each zone
Specialized trade (adds cost and time to Building commissioning)
Reverse-return piping materials-intensive, does not save energy
Real system conditions vary as heat loads change from design conditions
Traditional designs put additional capacity in place to overcome these issues, driving higher initial cost and higher operating costs
7. Characteristic curve of impeller correlates flow and pump head pressure
As controls change flow, head pressure changes inversely
Pressure changes travel in the system at the speed of sound
At low load, small pressure changes cause large changes in thermal output, causing hunting in the control system
Affinity Laws, Centrifugal Pumps:
Flow is proportional to speed
Pressure varies with square of speed
Power varies with cube of speed
Head pressure relative to flow increases at lower speeds Pump/System Interaction Issues
8. VFD vs Staged Pump Control
9. Effects of Coil Overflow Coils need low velocity, turbulent flow to transfer heat efficiently.
High flow = high water velocity = low coil ?T
Maximum heat output ˜ 114%
>90% of Control valves are oversized* by mechanical contractors to ensure design flow met (<5% probability @ target space temperature)
Oversized control valves restrict turn-down ratio = poor control @ light loads(100% probability)
10. Improving Coil Efficiency Coils are guaranteed to run at low capacity most of the year
Chiller efficiency varies* by2~3% / °F differential temperature change
Low flow = low water velocity = high coil ?T @ equal BTUh
At low loads and high ?T, small flow variations due to head pressure changes cause disproportionate coil heat transfer changes when using conventional control valve and static balancing valves
Resulting room temperature change forces control system to compensate
11. Installation Cost Analysis
12. Pressure-Regulated Control Valve Design
13. Uses high head pressure to operate a differential pressure regulator across valve seat
Flow & heat affected only by control valve
Matches the flow to the load in every heat transfer device, without excess flow, throughout full operating range
Fast, accurate system set-up
Applies at every operating point
Much more than just balancing
Simpler, lower-cost piping layouts
Extends HVAC equipment life
Improves efficiency
Lowers operating cost
The water-side equivalent of VAV control
Benefits of Regulated Flow Control
14. Honeywell VRN and VRW Valves
15. Inside a VRN-Series Valve
16. Features of the VRW-Series
17. Pressure Regulation Accuracy
18. Easy-To-Select Part Numbering System
19. VRN2 Model Selections
20. Reference Material Resources
www.specifyhoneywell.com – Includes wiring diagrams, guide specs, selection guide and other resources that are useful for Consulting Engineers.
Honeywell's Take-Off Service has been trained on product line
customer.honeywell.com/spectakeoff or email takeoff.service@honeywell.com
21. Barriers to Pressure-Independent Design Old habits die hard
Disbelief (“a BTU is a BTU”)
Delivered BTU’s rely on system efficiencies
Balancing valves not always used (= “premium” piping)
No balancing valve substitution to offset cost
Balancing valves fall under mechanical trade
Guide specs need to make note that balancing valves not required
“Flow Verification” report may still be required
Measure across the coil, not valve
Controls trade objects to carrying higher cost parts
2-position application alternatives:
Flow limiters cheaper, effective for 0%/100% operation
A pressure-regulated valve is a flow limiter at all valve positions
Some designs use control valve Cv to approximate balancing
Heat transfer = flow X time open X coil efficiency
Reverse-return piping mitigates need to balance, pushes spend to piping from controls
22. Writing P-I System Specifications Design to max-rated chiller ?T
Size piping and equipment to reduced flow rates
Specify pressure-regulated control valves in Division 23 09 13.33
Formerly MasterFormat Division 15
Mechanical section to specify balancing valves not required
Specify commissioning parameters for pump VFD’s
High pressure cut-out required if valves can dead-head flow
Audit coil flows at light loads, not just Design
Specify water quality requirements in Division 23 25 13
23. Honeywell's VRN and VRW-Series' Advantages Honeywell’s full line is designed to meet complete HVAC systems needs
Full range of sizes from ½" to 6" (1 gpm to 469 gpm)
VRN: ½ to 3" NPT, 1~95 gpm fixed sizes
VRW: 2-½ to 6" flanged, 39~469 gpm, adjustable ranges
Industry-leading precision for tighter control
Flow control accuracy within ± 5%
Maintain tighter ?T to optimize Chiller efficiency
Industrial-grade performance at HVAC prices
Unique Field-Serviceable control valve
Serviceability = long-term life = long-term savings
Field-proven technology
24. The New Solution to Flow Control
26. Future Discussions Other State-of-the-Art Controls and Sensors for Commercial HVAC and Integrated Security
27. Energy-Saving Controls and Systems Variable Frequency Drives
Demand-based (CO2) zone/central ventilation control
Wireless sensors
Pressure-independent VAV controllers
Fan coil & unit ventilator controllers
Programmable and communicating controllers and thermostats for temperature, humidity, and pressure
Economizer ventilation control and free cooling
Building Automation Systems
WebStat
Spyder
Niagara Framework Boiler Outdoor reset
Commercial boiler safety
Commercial combustion efficiency
Proportional, two-position, failsafe, and stay-in-place actuators for ventilation, fire & smoke dampers and valve control
Commercial HVAC (Division 23) globe, ball, and butterfly control valves from ½ to 20" (DN15~500)
Take-off Service
Energy monitoring
HVAC/security integration