Piping Systems

Piping Systems SERIES LOOP MONOFLO SYSTEM DIRECT RETURN REVERSE RETURN PRIMARY/SECONDARY SYSTEM BASIC PRIMARY SYSTEM SYSTEM SYZER

Hydronic System Open System Static Head Loss Friction Loss Valve and Fitting Loss Atmospheric Pressure NPSH(a) vs. NPSH(r)

Hydronic System Open System Static Head Loss Friction Loss Cooling Tower Static Head Loss Friction Loss Valve and Fitting Loss Atmospheric Pressure NPSH(a) vs. NPSH(r) Chiller

Open System Pressures Pump Pipe Friction Loss (Varies with flow) Total Static Head Condenser Total Suction Head (Known head loss) Basin Water Level Pump

Backflow Preventer Storage Water Heater DHW System HW CW HW CW HW CW Cooling Tower DHW System HW CW HW CW HW CW City Main Water Heater Water Heater Water Meter Backflow Preventer PRV Pump

Hydronic System Closed System Friction loss Valve and Fitting Loss NO Static Head Loss Pressurized System

Closed System Pressures Multi-Level Building 1 PSI = 2.31 Feet Head (ft) = head (psi) x 2.31 specific gravity

Closed System Pressures Example: 4-Story Building 60 feet to top of system 26 PSI of Static Pressure Static Pressure (26 PSI) +Minimum Pressure (4 PSI) 30 PSI PRV setting = 30 PSI

Closed System Pressures Example: Single Story Building 12 PSI fill pressure System can be 18 feet tall

Series Loop Piping

Monoflo System

Direct Return Pressure Calculations – Low Head Pressures (Piping in parallel) Heat Loss – Constant supply temperatures per load

Direct Return Piping

Reverse Return

Reverse Return Piping

Primary-Secondary Direct Return Supply Secondary Pumps Primary - secondary Common Return Primary Pumps 18 18

Primary-Secondary Reverse Return Terminals Terminals Terminals Supply Supply Return Secondary Pump Return Primary Chiller Pumps Common Pipe 19 19

Primary-Secondary-Tertiary Zone C Zone A Zone B Tertiary Pumps Common Pipe Secondary Pumps Modulating Control Valves Optional Variable Speed Pump DP Sensor Common Pipe 20 Primary Pumps 20

Primary-Secondary-Tertiary Hybrid Zone C Zone A Zone B Tertiary Pump Supply Secondary Pumps Common Pipe Primary Pumps Return

Primary Variable Speed Two-position Control Valves Flow Meter DP Sensor Modulating Valve The newest tool available to the designer is primary variable speed. Floor space can be gained in the equipment room as well a increased operating efficiencies, especially in single chiller designs. Control of this type of system is much more complex and doses not lend well to many retrofit opportunities. VFD VFD VFD 22 22

Primary / Secondary Terminology: “Pump #1 can be referred to as the source or primary pump and pump #2 as the load or secondary pump.” – 2004 ASHRAE Systems and Equipment Handbook, page 12.7

The flow rate entering a tee must equal the flow rate leaving the tee! Law of the “T” The flow rate entering a tee must equal the flow rate leaving the tee!

Law of the “T” 50 GPM 100 GPM 50 GPM

Law of the “T” 50 GPM 100 GPM 150 GPM

Law of the “T” 50 GPM 50 GPM 100 GPM 100 GPM 50 GPM

Law of the “T” 100 GPM 100 GPM 100 GPM 100 GPM 0 GPM

Law of the “T” 175 GPM 175 GPM 100 GPM 100 GPM 75 GPM

Prim. / Sec. -- Basics -- Common Pipe PRIMARY SECONDARY

Prim. / Sec. -- Basics -- Common Pipe Flow Pump OFF A B 100 gpm 100 100

Prim. / Sec. -- Basics -- Common Pipe Flow Pump ON - 100 gpm 100 gpm 0 100 gpm A B

Prim. / Sec. -- Basics -- Common Pipe Flow Pump ON - 50 gpm A 100 gpm 50 100 gpm B Mixing @ tee

Prim. / Sec. -- Basics -- Common Pipe Flow Pump ON - 200 gpm A B 100 gpm 100 100 gpm Mixing @ tee

Primary / Secondary --Bridge SUPPLY RETURN PRIMARY / SECONDARY COMMON

P/S bridge - Front Loaded Common Load = Production (flow in gpm) HWS TEMP. - 180F 500 SECONDARY PUMPS 500 OFF ON COMMON -- NO FLOW 500 500 EHW TEMP. 150 F HWR TEMP. - 150 F

P/S bridge - Front Loaded Common Load > Production (flow in gpm) HWS TEMP. - 171 F 500 SECONDARY PUMPS 700 OFF ON MIXING (500 @ 180) + (200 @ 150) 500 COMMON -- 200 700 EHW TEMP. 150 F HWR TEMP. - 150 F

Bridge Check Valve SUPPLY RETURN COMMON

P/S bridge - Front Loaded Common Production > Load (flow in gpm) HWS TEMP. 180F 1000 SECONDARY PUMPS 800 ON ON COMMON -- 200 500 500 MIXING (800 @150) + (200 @ 180) 800 Equally Loaded EHW TEMP. 156 F HWR TEMP. - 150 F

Primary-Secondary System Relationship SUPPLY RETURN PRIMARY / SECONDARY COMMON Step Function Linear Function

Single Boiler - Primary / Secondary HWS T3 T1 Boiler 3-10 pipe diameters between Tees T2 T4 HWR Single Boiler - Primary / Secondary

Dual Boiler - Primary / Secondary Boiler Control Boiler HWS HWR T1 T5 T6 T2 T3 T4 T7 Dual Boiler - Primary / Secondary

Dual Boiler - Primary / Secondary HWS T5 T3 T1 Boiler Boiler T7 T4 T2 T6 HWR Dual Boiler - Primary / Secondary

Four Boiler Primary Secondary System . .

Low Temperature Application Water Source Heat Pump or Radiant Heating Problems: Boiler Condensation! Fire tube: 160 Water tube: 140 Copper fin tube: 105 Version #1 B&G balance valves w/ bypass line to provide high temp inlet water to boiler HWS T3 T1 Boiler 3-10 pipe diameters between Tees T2 T4 HWR Single Boiler - Primary / Secondary

Low Temperature Application Water Source Heat Pump or Radiant Heating Problems: Boiler Condensation! Fire tube: 160 Water tube: 140 Copper fin tube: 105 Version #2 FPE Valve w/ bypass line to provide high temp inlet water to boiler HWS T3 T1 Boiler 3-10 pipe diameters between Tees T2 T4 HWR Single Boiler - Primary / Secondary

Low Temperature Applications Alternate: Condensing Boiler

Primary Only Piping For boilers that can handle variable flow

System Syzer Calculator Circular Slide Rule Analog Calculator Extremely Helpful Tool

Explanation Non-product specific Water Use Only

Heat Transfer Formula Q = m CP (T2 - T1) Btu / Hr = Energy = mass flow x specific heat x Delta T lb 1 Btu °F Btu / Hr = Hr 8.34 lb 1 Btu °F lb 60 Min 1 Hour Min 1 Gallon X Gal Btu / Hr = Energy = mass flow x specific heat x Delta T Btu / Hr = 500 GPM T

Scale 1: Heat Transfer / Flow 1 MBH = 1000 Btu/hr Δt from 1 to 200º F

Scale 1 - Example Problem Determine flow required for 150,000 Bth/hr using a 300DT. 10 gpm

“Tons” of refrigeration

Scale 1 - Example Problem Determine flow required for 20 tons cooling using a 100Dt. 20 tons x 12,000 BTUH/ton = 240,000 BTUH or 240 MBH 48 gpm

Scale 2: Pipe Sizing Window Milinch Ft/100ft ASHRAE

Scale 2: Example Problem Determine pipe size for 70 gpm in a typical hydronic system. 2½” Pipe 3.5’/100’ 3” Pipe 1.2’/100’

Scale 3: Flow Velocity Works with Scale 2

Scale 3: Example Problem What is the velocity of 1600 gpm through an 8” pipe? Problems? 10+ fps

Scale 3: Example Problem What is the velocity of 1600 gpm through an 8” pipe? Problems? 7 fps

Pipe Sizing / Fitting Pressure Drop System Syzer Jacket Based On Hydraulic Institute Standards One Method, There Are Others!

Equivalent Lengths Table 11’

Scale 4: Description Pipe Length - TEL - 50% rule Friction Loss Total Pressure Drop

Scale 4: Example Problem What is the total pressure drop in a pipe with a TEL of 130’ and flow rate of 200 gpm? Scale 2 2.3’/100’ Or…. 2.3’/100’ x 130’ = 3’

Scale 4: Example Problem The TEL of the longest circuit is 1500’. The head loss rate in the system piping is 3.4’/100’ at design flow. How much head does the pump have to provide to overcome the piping head loss? 1500’ 3.4’/100’ 50’

Scale 5: Flow/Head Relationship Q1= Known (design) flow Q2 = Final flow h1 = Known (design) head h2 = Final head

Scale 5: Example Problem A chiller has 12’ head loss at 100 gpm. What is its head loss at 150 gpm? 27’

Scale 5: Example Problem A closed system has a flow rate of 200 gpm and a head loss of 30’. Plot the system curve. Flow vs Head 100 7.5 150 17 200 30 250 46 300 67

Plotting the System Curve