HVAC Flow metering

8/7/2019 HVAC Flow metering

1/4

>10"

LAMP

W/HOO

14"

12"14"CT


2/4

Flow and Energy Measurement for Central Energy Plants

Improved Chiller Plant Control

Real-time Commissioning and Balancing Data

Continuous Monitoring of Chiller Performance (KW/ton)

Accurate flow and energy measurement provides:

Cooling Towers

BTU 12

CH4-CHWR

BTU 10

CH3-CHWR

BTU 8

CH2-CHWR

BTU 6

CH1-CHWR

CH-1

FM 13

CH4-CW

FM 11

CH3-CW

FM 9

CH2-CW

FM 7

CH1-CW

FM 14

CW MAIN

FM 3

CHW BYPASS

BYPASS

BTU 1SCHWS

BTU 2PCHWS

CH-2

CH-3

CH-4

PRIMARY LOOP

SECONDARY LOOP

BTU 4

BTU 5

SCHWS-NORTH

SCHWS-SOUTH

NORTH LOOP

SOUTH LOOP

RETURN

SUPPLY

Meter ScheduleMETER

#TAG DESCRIPTION

FLOWMETER

DISPLAY orBTU METER

BTU 1 SCHWS Secondary Chilled Water Supply F-1200BTU 2 PCHWS Primary Chilled Water Supply F-1200

FM 3 CHW BYPASS Chilled Water Bypass (decoupler) FB-1210 DB-1201

BTU 4 SCHWS-NORTH Sec. Chilled Water Supply - North Loop F-1200

BTU 5 SCHWS-SOUTH Sec. Chilled Water Supply - South Loop F-1200

BTU 6 CH1-CHWR Chiller 1 - Chilled Water Return F-1200

FM 7 CH1-CW Chiller 1 - Condenser Water F-1210







Condenser Water Main F-1210 D-1201

D-1201

D-1201

D-1201

D-1201

To ensure the highest return on investment, a comprehensive metering program is essential formanaging today's complex central energy plants.

Traditionally, energy calculations

(if done at all) are performed within thebuilding automation system based on

analog inputs from a flow transmitterand two temperature sensors.

ONICON's Dual Turbine Flow Meter

has become the recognized standardfor accurate, reliable flow measurementat a reasonable cost. However, the

effect of using typical HVAC gradetemperature sensors with analog

control inputs for energy calculationsis widely misunderstood, resultingin relatively high error for the

energy calculation.

ONICON's System-10 BTU Meterutilizes a calibrated system approach

to provide highly accurate flow,

temperature and energy data.Furthermore, with a serial network

communication option, this system canactually be less expensive than

traditional energy calculation methods.

Contact an ONICON Representativetoday to learn more about this excitingimprovement in energy measurement.

System-10System-10

System-10

System-10

System-10

System-10

System-10

System-10

A Note on Energy Measuremenin Central Plant Environments

POINTS LIST

gpm, tons, ton-hrs, Tsupply, Treturn

gpm

gpm, flow direction

gpm

gpm

gpm

gpm








CW MAINFM 140352B-1 2-1


3/4

FLOW

RETURN

SUPPLY

POWER

SYSTEM-10BTU METER

Individual Chilleror Boiler

Supply

Sensor

ReturnSensor

INCORPORATED

BTU X 10,000

AVAILABLE OUTPUT SIGNALSTO CONTROL SYSTEM

Serial Network Options

BACnet

JCI-N2LON

Siemens-P1

Pulse/Analog Signal Options

Energy Total (BTU) Dry Contact

Energy Rate (Tons) 4-20 mA

Flow Rate (GPM) 4-20 mA

Supply Temp (F) 4-20 mA

Return Temp (F) 4-20 mA

Delta-T (F) 4-20 mA

BTU Meters with Pulse/Analog OutputsFor applications where the existing network protocol is not

compatible with the System-10, traditional analog and pulse

type outputs can be used. In this case, a single pulse output

for energy total, and up to four analog outputs (for flow rate,

energy rate and temperatures) can be provided. Each output

for each meter must be wired to a building control system field

panel input point (AI or BI) using a twisted pair.

Networked Energy MetersBTU Meters configured with serial network communications

offer simplified wiring and greatly reduced installation cost

compared to traditional analog/pulse type outputs. The data

provided (with a single 2-3 wire LAN connection) includes:

energy total, energy rate, flow total, flow rate, supply

temperature, return temperature, delta temperature.

A Calibrated System for Energy Measurement

Highly Accurate, Surprisingly Affordable

24 or 120 VACInput Power

Provides all dataon 2-3 wires}

Typical Flow Meter Installation with Analog Output to Control System

(BTU calculation performed by control system)

Detail of hot tap adapterwith turbine assemblywithdrawn

FLOW

SystemMains

AVAILABLE OUTPUTSIGNALS TO

CONTROL SYSTEM

Flow Rate (GPM)

4-20 mA

INCORPORATED

Local Display of Flow, Temperatureand Energy Data

0352C-1 2-1


4/4

1500 North Belcher Road, Clearwater, Florida 33765 Tel (727) 447-6140 Fax (727) 442-5699www.onicon.com E-mail: [email protected]

0352D-1 2-1

Energy Measurement and Flow Measurement SpecificationsFor Central Energy Plant Applications (CHW, HW, CW)

Energy Measurement System SpecificationThe entire Energy Measurement System shall be built and calibrated by a single manufacturer, ONICON Incorporated,

and shall consist of a flow meter, two temperature sensors, a BTU meter, temperature thermowells, and all required

mechanical installation hardware. A certificate of NIST* traceable calibration shall be provided with each system.

BTU Meter: Provide an ONICON System-10 BTU Meter. The BTU meter shall provide the following points both at

the integral LCD and as outputs to the building control system: Energy Total, Energy Rate, Flow Rate, Supply

Temperature and Return Temperature. Output signals shall be either serial network (protocol conforming to

BACnet, LON, JCI-N2 or Siemens-P1) or via individual analog outputs. An isolated dry contact output shall be

provided for energy total. Each BTU meter shall be factory programmed for its specific application, and shall be

re-programmable using the front panel keypad (no special interface device or computer required).

Temperature sensors: Temperature sensors shall be loop-powered current based (mA) sensors and shall be

bath-calibrated and matched (NIST* traceable) for the specific temperature range for each application. The calculated

differential temperature used in the energy calculation shall be accurate to within 0.15F (including the error from

individual temperature sensors, sensor matching, input offsets, and calculations).

Flow Meter: Provide an ONICON Model F-1200 Dual Turbine Flow Meter, complete with all installation hardware

necessary to enable insertion and removal of the meter without a system shutdown. The flow meter shall be

hand-insertable up to 400 psi. The flow meter shall have two contra-rotating axial turbines, with electronic

impedance-based sensing and an averaging circuit to reduce measurement errors due to swirl and flow profile

distortion. Each flow meter shall be individually wet-calibrated against a primary volumetric standard that is accurate

to within 0.1% and traceable to NIST*. The manufacturer's certificate of calibration shall be provided with each flow

meter. Accuracy shall be within 0.5% of rate at the calibrated velocity, within 1% of rate over a 10:1 turndown

(3.0 to 30 ft/s) and within 2% of rate over a 50:1 turndown (from 0.4 to 20 ft/s). Output signal shall be a 0-15 V square

wave pulse. Bi-directional meters shall be FB-1200 Series and shall include an isolated contact closure output for direc

Flow Measurement Station Specification

Flow Meter: Provide an ONICON Model F-1210 Dual Turbine Flow Meter complete with all installation hardware

necessary to enable insertion and removal of the meter without a system shutdown. The flow meter shall be

hand-insertable up to 400 psi. The flow meter shall have two contra-rotating axial turbines, with electronic

impedance-based sensing and an averaging circuit to reduce measurement errors due to swirl and flow profile

distortion. Each flow meter shall be individually wet-calibrated against a primary volumetric standard that is accurate

to within 0.1% and traceable to NIST*. The manufacturer's certificate of calibration shall be provided with each flow

meter. Accuracy shall be within 0.5% of rate at the calibrated velocity, within 1% of rate over a 10:1 turndown

(3.0 to 30 ft/s) and within 2% of rate over a 50:1 turndown (from 0.4 to 20 ft/s). The flow meter shall include integral

analog output(s), 4-20 mA, 0-10V, or 0-5V. Bi-directional meters shall be FB-1210 Series and shall include an isolated

contact closure output for direction.

Optional Flow Display: Provide a D-1200 Series Display Module for local indication of flow rate and/or total.

For bi-directional applications, provide a DB-1200 series Display Module.

*National Institute of Standards and Technology

INCORPORATED

HVAC Flow metering

Documents

Transcript of HVAC Flow metering