Hydronic Loop Performance: Design vs. Installed Why design and modeling data don’t always match a...

Hydronic Loop Performance:Design vs. Installed

Why design and modeling data don’t always match a building’s actual performance

David Kandel

New Mexico Association of Energy Engineers May 26, 2015

Agenda

Hydronic Loop Performance: Design vs. Installed• Design and Modeling Assumptions & Coil Behavior• Performance Problems

• Valve Sizing• Valve Authority (Static vs Dynamic Balancing)• Coil Performance

• Potential Solutions

Valve Specs

• Design / Modeling Assumptions• Proper Valve Sizing• Stable System Pressures• Perfect Valve Authority

Valve / Coil Performance

Coil Performance

Co

il P

ow

er /

Flo

w

Flow / Control Signal

ΔT

BTUh

Valve GPM

Resulting Coil Output

ΔT

Agenda

Hydronic Loop Performance: Design vs. Installed• Design and Modeling Assumptions & Coil Behavior• Performance Problems

• Valve Sizing• Valve Authority• Coil Performance

• Potential Solutions

Hydronic Valve Sizing

P

gpm Cv

Example:• Coil Requires 250 GPM• Design DP for valve, 4 psi • DP of Valve not to exceed 5

psi

1252

250

4

250 Cv

Hydronic Valve Sizing

Example:• Coil Requires 250 GPM• Design DP for valve, 4 psi • DP of Valve not to exceed 5

psi

1252

250

4

250 Cv

Hydronic Valve Sizing

2GPM

P

Cv

Checking DP

Example:• Coil Requires 250 GPM• Design DP for valve, 4 psi • DP of Valve not to exceed 5

psi

Hydronic Valve Sizing

psi7.790

250 P

2

2GPM

P

Cv

Checking DP

psi2.2170

250 P

2

Piping Options

Coil Balance Valve

Control Valve

Coil Control Valve

Coil Flow Limiting

Valve

Control Valve

No Balancing DeviceOversized Control Valves

Coil Control Valve

Coil Control Valve

Near Pump:• High ΔP causes massive

overflow

ΔP35 psi

ΔP8 psi

Far From Pump:• Oversized Valve cause

overflow• No Protection from pressure

changes

Traditional Balancing ValveOversized Control Valves

Near Pump:• Major Valve Authority issues• No Protection from pressure

changes

Balance Valve

Balance Valve

Far From Pump:• Minor Valve Authority issues• No Protection from pressure

changes

Coil Control Valve

Coil Control Valve

ΔP35 psi

ΔP10 psi

Flow Limiting ValveOversized Control Valves

Near Pump:• Major Valve Authority issues• No Protection from pressure

changes below full flow

Far From Pump:• Minor Valve Authority issues• No Protection from pressure

changes below full flow

Coil Control Valve

Coil Control Valve

ΔP35 psi

ΔP10 psi

Flow Limiting

Valve

Flow Limiting

Valve

Agenda

Hydronic Loop Performance: Design vs. Installed• Design and Modeling Assumptions & Coil Behavior• Performance Problems

• Valve Sizing• Valve Authority• Coil Performance

• Potential Solutions

15

Valve Authority

Branchp

valvepCoil

Balance Valve

branch

valve

p

pA

Static BalancingFull Flow

Near Pump:• High Branch Differential• High Pressure Drop on

Balancing Valve

Balance Valve

Balance Valve

Far From Pump:• Low Branch Differential• Low Pressure Drop on

Balancing Valve

Coil Control Valve

Coil Control Valve

ΔP20 psi

ΔP10 psi

4PSI

4PSI

2PSI

4PSI

4PSI

12PSI

100%

Static BalancingManual Balancing Valves

• 100% flow• No pressure drop• 100% flow• 12 psi pressure drop

• 20% flow• ? psi pressure drop

Static BalancingManual Balancing Valves

• Limit the maximum coil flow…

• What happens below max flow?

Static BalancingAutomatic Balancing Valves

Control Valve + Automatic Balancing valve = PI Valve

Static BalancingLess than Full Flow

Near Pump:• Massive overflow

Balance Valve

Balance Valve

Far From Pump:• Small overflow

Coil Control Valve

Coil Control Valve

ΔP20 psi

ΔP10 psi

5PSI

< 4PSI

1PSI

14PSI

< 4PSI

2PSI

20%

Dynamic Balancing

Dynamic BalancingAll Flows

Near Pump:• Exact GPM

Far From Pump:• Exact GPM

Coil PI Valve

CoilPI Valve

ΔP20 psi

ΔP10 psi

0 to 100%

Agenda

Hydronic Loop Performance: Design vs. Installed• Design and Modeling Assumptions & Coil Behavior• Performance Problems

• Valve Sizing• Valve Authority• Coil Performance

• Potential Solutions

Valve / Coil Performance

Coil Performance

Co

il P

ow

er /

Flo

w

Flow / Control Signal

ΔT

BTUh

Valve GPM

Resulting Coil Output

ΔT

Low Delta T at the Coil

T500Q(Btu/h) GPMPower Output:

Operating in the Waste Zone1. Pumping more Water2. Reduced Delta T3. No additional BTUs

Low Delta T at the Coil

Coil Degradation

Heat Transfer of Coil Degrades Over Time• Damage to coil or fins• Air-side fouling• Water-side fouling

Coil Degradation

Coil Performance

Co

il P

ow

er /

Flo

w

Flow / Control Signal

ΔT

BTUh

Valve GPM

Resulting Coil Output

ΔT

Coil Performance

Coil Degradation

Wa

ste

Zon

e

Co

il P

ow

er /

Flo

w

Flow / Control Signal

ΔT

Agenda

Hydronic Loop Performance: Design vs. Installed• Design and Modeling Assumptions & Coil Behavior• Performance Problems

• Valve Sizing• Valve Authority• Coil Performance

• Potential Solutions• Pressure Independent Valves• Delta T Limiting

Pressure Independent ValvesBetter Performance

• No Issues with oversizing• Perfect Valve Authority• Stable control, part load and full load

Pressure Independent ValvesPI Valve Technologies

Mechanical Regulator Flow Meter

Pressure Independent TechnologyMechanical Regulator

Pu Pd

Pd

Pressure Independent TechnologyMechanical Regulator

Pu Pd

Pd

Pressure Independent TechnologyElectronic Pressure Independence

Real Time Flow Measurement

Unrestricted Flow Pattern

Advantages of Electronic PI ValvesDP Reset Strategy

DP reset can now be employed with Pressure Independence

Advantages of Electronic PI ValvesDP Reset Strategy

At Design• “Critical Zone” valve full

open at 5 psi

Coil ePIV

Coil ePIV

100%

5PSI

100% Open

9PSI

9PSIAdvantages of Electronic PI ValvesDP Reset Strategy

At High Demand• “Critical Zone” valve full

open at 5 psi

Coil ePIV

45%

5PSI

At Reduced Demand• “Critical Zone” valve driven

open, as pump reduced as far as possible.

40%

50% Open

8PSI

65% Open80% Open90% Open

8PSIAdvantages of Electronic PI ValvesVFD Reset Strategy

At High Demand• “Critical Zone” valve full

open at 5 psi

Coil ePIV

45%

5PSI

At Reduced Demand• “Critical Zone” valve driven

open, as pump reduced as far as possible.

4PSI3PSI2PSI

40%35%30%

7PSI6PSI

Pressure Independent TechnologyDelta T Limiting

Pressure Independent TechnologyDelta T Limiting

Delta T LimitingCase Study: Large Tech Company in North Carolina

Position Control 240 GPM

144 GPM

96 GPM

Pressure Independent

P.I.+DT Management

Hydronic Loop Performance: Design vs. Installed• Design and Modeling Assumptions & Coil Behavior• Performance Problems

• Valve Sizing• Valve Authority• Coil Performance

• Potential Solutions• Pressure Independent Valves• Delta T Limiting

Questions?david.kandel@us.belimo.com