Balancing Basics Mike Weisman, ASHRAE Treasurer ASHRAE Golf Outing: - PowerPoint PPT Presentation

Balancing Basics Mike Weisman, ASHRAE Treasurer ASHRAE Golf Outing: May 18 th , 2018! HEATHERWOODE

Agenda: • Why balance? • Manual Balancing Valves • Manual Balancing Process • Automatic Flow Controllers • Partial Load Conditions: Hydraulic Interactivity • Pressure Independent Control Valves

Two Reasons for Balancing 1. Comfort • Satisfying Flow Requirements 2. Delta T Realization • Optimize Coil Performance • Eliminate Overflow – Partial Load Condition • More efficient equipment, less required pump heat

Hydronic Heating Air In Terminal 180 ° HWS Terminal Energy (Heat) is produced at a central location and Terminal distributed to various locations via water 140 ° HWR Terminal Boiler Air Out

Why Balance? • Without balancing, the circuits closest to the pump would overflow and those further away underflow • “I don’t need balancing valves! The control valves will throttle the flow.”

Balancing Basics Simplified building schematic 0’ 50’ 50’ 50’ 5’ Terminal Each leg has 5’ of resistance 1 13gpm 3gpm The lowest terminal has 20’ of 5’ 5’ resistance, the furthest has 50’ 10’ 5’ 40’ 40’ 50’ 50’ Terminal 13gpm 10gpm 7gpm 2 5’ 5’ Different resistances cause 20’ 50’ 30’ 30’ 50’ 5’ Terminal differing flows 3 13gpm 13gpm 10gpm By adding manual balancing 5’ 5’ valves, 30’ 50’ 20’ 20’ 50’ 5’ Terminal we can equal out all the 4 13gpm 10gpm 17gpm 5’ 5’ resistances and therefore all the flows 5’

Why Balance?

Manual Balancing Valves

𝑹 = 𝑫𝒘 × ∆𝑸

Manual Balancing Valves • Calibrated Orifice vs. fixed orifice (Venturi) • Ball, Globe, Butterfly • Accuracy • Precision • Typically Balancing AND Shut Off

Manual Balancing Process Lifts, Ladders, Drop Ceilings, Furniture…

Proportional Balancing 2gpm 2gpm 2gpm • Set valves to the correct ratio, they will all be in the 2gpm 2gpm 2gpm same % of overflow or underflow 2gpm 2gpm 2gpm • Balance each section 2gpm 2gpm 2gpm within itself • Use partner valve to balance sections together 8gpm 8gpm 8gpm

Splitting into Hydronic Modules

Balancing a Module

Hydraulic Interactivity

Balancing a Module

Balancing a Module

Balancing a Module

Order for Balancing Modules

Full Pump Heat, Valves Wide Open

Proportional Branches

Balance All Partner Valves

Optimize Pump Head

Manual Balancing Reality — Infinite Solutions

Automatic Flow Controllers

Automatic Flow Controllers • “Flow Limiter”: A bit of a misnomer. • Full Flow, Whether you need it or not • Pressure-Independent Balancing Valve • Select cartridge based on design flow • Install It, Check Pressure, Forget About It • Still NEED Partner Valves! • Operating Range (Typical): 2-32psi dP Cartridge Design Benefits • Maintains ±5% accuracy of design flow • Terminals can be flushed with cartridge in place • Reduced commissioning time • Simple selection and identification of flow rate • Can be fitted adjacent to bend or fitting in pipe

Automatic Flow Controllers

Automatic Flow Controllers 𝑹 = 𝑫𝒘 × ∆𝑸 • Flow is constant within operating dP range • The Cv of the cartridge adapts to the dP within the operating range to provide constant design flow

Partial Load Conditions

Differential pressure variations % of heating season 58% Heating  P  2 q below this load Dp piping Power 100% 120% 100% 80% 80% 60% Thermal plant load [%] 60% 50 % 40% Dallas 40% load 4% press. 20% 20% drop Thermal plant load [%] 0% 0% % of cooling season below this load 0% 50% 100% 150% 200% 0% 20% 40% 60% 80% 100% Flow Flow 20 % At constant supply flow water temperature 68% Pressure drops are reduced Cooling to 4% of their design value. April 2010 32

Control loop Set value U Disturbances Controller Actuator Valve Terminal Power Room Sensor Signal Lift Flow output x k2 k3 k4 k5 k1 x = 0 - 10 volts 0-100% 0-100% 0-100% x U - x x = controlled value Power output % Flow in% Power output % Heat output in % Flow in % Heat output in % 100 100 100 90 90 90 80 80 80 70 70 70 60 60 60 = + 50 50 50 40 40 40 30 30 30 20 20 20 10 10 10 Lift h in % Lift h in % Flow in % 0 0 0 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 Terminal unit characteristic Control valve characteristic April 2010 33

Manual Balancing 50’ 50’ 10gpm 50’ 3gpm 10gpm Terminal 1 0gpm Terminal 1 Terminals are set to 10gpm with static As other terminals try to modulate, When one control valve closes down, valves. When all control valves are As more portions of the building overflow situation intensifies, the other terminals overflow, wasting close, the situation gets worse open, system is comfortable & 40’ 50’ 10gpm 50’ 13gpm 40’ 7gpm increasing energy costs energy Terminal 2 Terminal 2 15gpm 10gpm 13gpm 0gpm efficient 30’ 50’ 13gpm 50’ 10gpm 30’ 13gpm Terminal 3 Terminal 3 13gpm 10gpm 11gpm 8gpm • All circuits are interactive • dP sensor placement is critical 20’ 50’ 10gpm 50’ 13gpm 20’ 17gpm Terminal 4 Terminal 4 13gpm 10gpm 15gpm 17gpm

Overflow = Low Δ T 180 ° 10gpm 15gpm 20gpm 140 ° 160 ° 170 ° Design: 10GPM, 40 °Δ T

Overflow Effects on Coils • Coils are designed to flow a certain • 150% flow = 110% heat amount • Over 100% flow, the efficiency of the • 250% flow = 120% heat coil reduces 120% 100% 80% 60% Heat 40% 20% 0% 220% 0% 20% 40% 60% 80% 100% 120% 140% 160% 180% 200% 240% Flow

Autoflow Valve with Modulating Control Valve • In partial loads, a control valve will start to close (decrease Cv) • As the control valve modulates, the automatic balancing cartridge will try to maintain design flow (increase Cv) • Eventually the control valve will decrease available head pressure enough to modulate flow • Also contributes to the same low delta T syndrome. 𝑹 = 𝑫𝒘 × ∆𝑸

Control Valve Authority with an Automatic Balancing Valve Required Flow Actual Flow 10gpm 5gpm 2.5gpm 10gpm 5gpm 7.5gpm

Manual Valves: Pros and Cons • PROS • Performs well with a modulating control valve • Flexible for changes to the space/water quality • With proper balancing, can decrease pump head • CONS • Labor intensive balancing process/commissioning • Very dependent on quality of the balancing contractor • Susceptible to overflow situations

Automatic Valves: Pros and Cons • PROS • ONE pass balancing • ELIMINATES interactivity in the system • Eliminates overflow situations • CONS • “Fighting” with modulating control valves • Cartridges have tiny openings: • Higher pressure drop, susceptible to clogging • Is the correct cartridge installed?

Best of Both Options? • Pressure Independent, Balancing Control Valves • Two valves in one: Balancing Valve, Control Valve with Pressure Regulator • Pressure drop across the valve seat is fixed • Very precise modulation! • Actuator technology can simplify balancing process Be aware of minimum start pressure! Up to 5 psi for smallest valves! 𝑹 = 𝑫𝒘 × ∆𝑸

Control loop Set value U Disturbances Controller Actuator Valve Terminal Power Room Sensor Signal Lift Flow output x k2 k3 k4 k5 k1 x = 0 - 10 volts 0-100% 0-100% 0-100% x U - x x = controlled value Power output % Flow in% Power output % Heat output in % Flow in % Heat output in % 100 100 100 90 90 90 80 80 80 70 70 70 60 60 60 = + 50 50 50 40 40 40 30 30 30 20 20 20 10 10 10 Lift h in % Lift h in % Flow in % 0 0 0 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 Terminal unit characteristic Control valve characteristic April 2010 42

Autoflow vs. PICV Always be able to verify flow!

Applications…. • ON/OFF Control: Chilled beam, fin tubes, WSHP, UH • Automatic flow controller • Modulating Control: FCU, VAV, above 1 GPM • Manual balancing valve • Systems with lots of diversity in loads, fluctuating dP • Automatic flow controller, PICV • Large Flows (AHUs), Precise discharge air temp. • PICV • Retrofits, Expansions • PICV

Final Thoughts… • Follow the pressure, not the flow • 1-2 degree change in operating conditions can have a HUGE impact on system performance! • One solution doesn’t fit every application! • The more balancing shutoff valves, the better!

Questions?