Hydronic Balancing Chris Wolak

Chris Wolak 1 Outline • Introduction • Static Balancing • Dynamic Balancing

Chris Wolak 2 Two Reasons for Balancing

• Manual balancing • Pressure Independent • On-off Control balancing • Single Speed Pump • Modulating Control • Variable Speed Pump

Chris Wolak 3 Why Balance? • Without balancing, the circuits closest to the pump would overflow and those further away underflow

Chris Wolak 4 ASHRE 90.1-2010

6.7.2.3.3 Hydronic System Balancing. Hydronic systems shall be proportionally balanced in a manner to first minimize throttling loss; then the pump impeller shall be trimmed or pump speed shall be adjusted to meet design flow conditions

Chris Wolak 5 Static Balancing

Simplified Building Schematic Terminal50’ 5’ 0’ 10gpm3gpm1 Each leg has 5’ of resistance. 5’ 5’ Terminal40’50’ 5’ 10’ 10gpm7gpm2 Different resistances cause 5’ 5’ different flows 20’ Terminal30’50’ 5’ 13gpm10gpm3 By adding manual 5’ 5’ balancing valves, 30’ 5’ we can equal out all the Terminal20’50’ 17gpm10gpm4 resistances and 5’ therefore all the flows 5’ 5’

Chris Wolak 6 Manual Balancing Valves

• Three Functions: – Throttling – Flow Measurement – Shutoff

ASHRAE Handbook 2013 Systems & Equipment, Chapter 47. Valves

Chris Wolak 7 What is Cv? 10 psi

11 푆퐺1 psi 퐶 = 퐹 푣 ∆푃

5gpm

Cv?

Chris Wolak 8 Proportional Balancing

2gpm 2gpm 2gpm Balance each • 2gpm 2gpm 2gpm section within itself 2gpm 2gpm 2gpm • Use partner 2gpm 2gpm 2gpm valve to balance sections

together 8gpm 8gpm 8gpm

Chris Wolak 9 Reverse-Return Two-Pipe Reverse-Return

• Theoretically, reverse- 50’ 5’ 50’ 5’ return piping can self 17gpm 10gpm balance 5’ 5’ 5’ 5’ • Each terminal has to 40’ 5’ 50’ 5’ have the exact same 13gpm 10gpm 5’ 5’ 5’ piping 5’ 30’ 5’ 50’ 5’ 20’ • Hoses, strainers, dirty 7gpm 10gpm coils will effect 5’ 5’ 5’ 5’ balancing 20’ 5’ 50’ 5’ • No way to verify flows 3gpm 10gpm • Adds extra piping 5’ 5’ 5’ 5’ 5’

Chris Wolak 10 Two Reasons for Balancing

• Manual balancing • Pressure Independent • On-off Control balancing • Single Speed Pump • Modulating Control • Variable Speed Pump

Chris Wolak 12 50’ Static Balancing 50’Terminal50’Terminal 10gpm 3gpm 11 10gpm0gpm Terminals are set to 10gpm with static WhenAs other one terminals control valvetry to closes modulate, down, Asvalves. more When portions all controlof the building valves are theoverflow other situation terminals intensifies, overflow, wasting 40’ close,open, thesystem situation is comfortable gets worse & Terminal 2 energyincreasing energy costs 50’Terminal40’ 10gpm13gpm 7gpm 2 13gpm15gpm10gpm0gpm efficient

30’ 30’50’TerminalTerminal 13gpm10gpm 33 10gpm13gpm11gpm8gpm

20’ 20’50’TerminalTerminal 17gpm10gpm13gpm 44 10gpm13gpm15gpm17gpm

Chris Wolak 13 What is Overflow? • Buildings are balanced to the full load • As circuits of a building shut down, others will see excess flow • Coils will still produce sufficient heat but will use more energy then is needed

Chris Wolak 14 Why Prevent Overflow • Pump Energy • Noise / Pipe Erosion • Boiler / Chiller Efficiency • Control Valve Authority • ASHRAE 90.1

Chris Wolak 15 Variable Speed Pumps Variable Speed Pump • Variable flow systems reduce pumping costs at partial load • Need to maximize pumping energy savings while keeping a 100% operational Constant Speed Pump cooling/heating system

Chris Wolak 16 Overflow Effects on System • Overflow causes water velocity that is higher than expected per design flow • Higher water velocity leads to erosion in elbows & heat exchangers • Control valves work with very short open/close cycles – Limits actuator life

Chris Wolak 18 Overflow Effects on Coils

• Coils are designed to flow a certain amount • 150% flow = 110% heat • Over 100% flow, the efficiency of the coil reduces • 250% flow = 120% heat 120%

100%

80%

60% Heat 40%

20%

0% 0% 20% 40% 60% 80% 100% 120% 140% 160% 180% 200% 220% 240% Flow

Chris Wolak 19 Differential Temperature (∆T)

Chris Wolak 20 Overflow = Low ΔT

180°

10gpm15gpm20gpm

Design: 160170140° 10GPM, 40°ΔT

Chris Wolak 21 ASHRE 90.1-2010

6.5.4.2 Hydronic Variable Flow Systems. HVAC pumping systems having a total pump system power exceeding 10hp that includes control valves designed to modulate or step open and close as a 6.4.2.2 Pump Head. Pump differential pressure function of load shall be designed for variable fluid flow and shall (head) for the purpose of sizing pumps shall be be capable of reducing pump flow rates to 50% or less of the determined in accordance with generally accepted design flow rate…The control or devices shall be controlled as a engineering standards and handbooks acceptable to function of desired flow or to maintain a minimum required the adopting authority. The pressure drop through differential pressure. Differential pressure shall be measured at or each device and pipe segment in the critical circuit near the most remote heat exchanger or the heat exchanger at design conditions shall be calculated requiring the greatest differential pressure

Chris Wolak 22 EQM Control Valve

Chris Wolak 23 Pressure Independent Control Valve

Chris Wolak 24 50’ CurrentDifferential Balancing Pressure Strategies Control 50’Terminal50’Terminal 10gpm 3gpm 11 10gpm 0gpm LowHigh ControlControl ValveValve AuthorityAuthority

Terminals are set to 10gpm with static WhenAsPressure other oneother terminalsindependent control valves valve trymodulate, tosystems closes modulate, desired down, 40’ AsWhenvalves. more one When portions control all controlof valve the buildingcloses, valves are 50’Terminal40’Terminal 10gpm13gpm 7gpm 22 theoverflowmaintainflow other is achieved situationa terminals constant through intensifies, overflow,flow highrate wastingandcontrol 13gpm15gpm10gpm0gpm close,desiredopen, thesystem control situation is iscomfortable maintained gets worse & energyincreasingpropervalve authority control energy valve costs authority efficient

30’ 30’50’TerminalTerminal 13gpm10gpm 33 10gpm13gpm11gpm8gpm5gpm

20’ 20’50’TerminalTerminal 17gpm10gpm13gpm 44 10gpm13gpm15gpm17gpm

Chris Wolak 25 On-offModulating Control Control

76°

72°

68° Room Temp Room

6:00am Time

Chris Wolak 27 Control Valve Authority with an ABV

Required Flow Actual Flow

7.5gpm2.5gpm10gpm5gpm 10gpm5gpm

Chris Wolak 28 Differential Pressure Controller

Chris Wolak 29 STAD (Flow measuring)

P3 P2

(DP Stabilization)

Chris Wolak 30 Dp Controller Placement

Chris Wolak 31 STAP Placement

Chris Wolak 32 Low ΔT

180°

10gpm15gpm20gpm

140160170°

Chris Wolak 34 Pressure Independent Options

Standard Control Pressure Valve Independent Control Valve

Manual Balancing Valve

Dp Controller

Chris Wolak 35 Review Questions

• Which organization requires systems to be proportionally balanced? • What type of balancing is more energy efficient? • No balancing • Static balancing • Dynamic balancing • What causes low ΔT? • Why are modulating control valves used? • Energy efficiency • Better room temperature control • Lower cost • What does EQM stand for?

Chris Wolak 36