Honeywell Solid State Economizer System Engineering Guide

Solid State Economizer System

W7212/13/14

C7400

M7215

C7150

C7046

C7232B

C7632A

C7660

(CONSISTING OF: C7046C DISCHARGE AIR SENSOR OR C7150B MIXED AIR SENSOR, C7232 OR C7632 CARBON DIOXIDE SENSOR, C7400 SOLID STATE ENTHALPY SENSOR OR C7660 SOLID STATE TEMPERATURE SENSOR, M7215 DAMPER ACTUATOR AND W7212, W7213 OR W7214 SOLID STATE ECONOMIZER LOGIC MODULE)

SYSTEM ENGINEERING GUIDE

FEATURES

C7046C Discharge Air Sensors have probe lengths of 8 in. (203 mm) and nominal sensor resistance of 3000 ohms at 77°F (25°C).

• No setting or calibration required.

• Solid state components not affected by dust or dirt.

• Fast reacting.

• Rugged aluminum insertion probe.

C7150B Mixed Air Sensor is used with the M7215 Damper Actuator to sense mixed or discharged air in rooftop packaged air conditioning equipment.

• No setting or calibration required.

APPLICATION

The Solid State Economizer System provides an economical method of providing cooling air by incorporating outdoor air in the first stage of cooling in heating, ventilating and air conditioning (HVAC) systems. The Solid State Economizer System consists of the C7046 Discharge Air Sensor, C7150 Mixed Air Sensor, C7232 or C7632 Demand Control Ventilation (DCV) Sensor, C7400 Enthalpy Sensor or C7660 Dry Bulb Temperature Sensor, M7215 Damper Actuator, and W7212 Solid State Economizer Logic Module.

C7232 and C7632 DCV Sensors are stand-alone carbon dioxide (CO with heating ventilation and air conditioning (HVAC) controllers. They measure the CO space or duct. They are used in HVAC systems to control the amount of fresh outdoor air supplied to maintain acceptable levels of CO

• C7232 models available with LCD that provides sensor

• Non-Dispersion-Infrared (NDIR) technology used to

• Gold-plated sensor provides long-term calibration

• Device provides voltage output based on CO

• C7232 models available with SPST relay output.

• Used for CO

• Automatic Background Calibration (ABC) algorithm

• C7632 has fixed 0 to 10 Vdc from 0 to 2000 ppm. No

) sensors for use in determining ventilation necessity

concentration in the ventilated

in the space.

readings and status information.

measure carbon dioxide gas.

stability.

levels.

based ventilation control.

based on long-term evaluation reduces required typical zero-drift check maintenance.

adjustments are necessary.

(Continued)

63-2576—02

SOLID STATE ECONOMIZER SYSTEM

CAUTION

C7400 Solid State Enthalpy Sensor and C7660 Solid State Temperature Sensors are used with the W7212 Solid State Economizer Logic Module to allow using outdoor air as the first stage of cooling in HVAC systems.

• C7400 senses and combines temperature and humidity of outdoor air (heat index).

• C7660 senses dry bulb temperature only.

• Long-lasting, solid state sensing element is accurate and stable over time.

• When enthalpy/temperature of outdoor air increases, the outdoor air damper closes to a preset minimum position.

• When enthalpy/temperature of outdoor air is low, the outdoor air damper opens to reduce the building cooling load.

• Provides 4 to 20 mA output signal to the Economizer Logic Modules; setpoint is located on economizer control.

• Maximum economizer savings is achieved with two C7400 Enthalpy Sensors connected to one Economizer Logic Modules for differential enthalpy changeover control.

M7215 Damper Motors are 25 lb-in. spring return damper actuators that provide modulating control of economizer systems, ventilation dampers and combustion air dampers used in residential or commercial HVAC equipment.

• M7215 Damper Motors provide modulating control of economizer dampers from a 2-10 Vdc controller.

• Quiet, high efficiency drive motor.

• High impact, glass-fiber reinforced plastic case is rugged, lightweight and corrosion resistant.

• Provides 2-10 Vdc output signal proportional to the shaft position.

W7212 Economizer Logic Modules are used with C7232 Demand Control Ventilation (DCV) Sensors, and solid state C7400 Enthalpy Sensors or C7660 Dry Bulb Temperature Sensors to proportion outdoor and return air dampers for control of free cooling in commercial HVAC equipment.

• Operates from thermostat and DCV sensor to provide a totally integrated control system.

• Solid state control package provides accurate, reliable and stable control.

• Mounts on M7215 Motor or duct work.

• Control can be tempered by DCV and fan cycling.

• Used with Honeywell actuators.

• Combines minimum and DCV maximum damper position potentiometers with compressor staging.

• Relay functions with solid state enthalpy or dry bulb changeover control.

• Terminals included for switching between Occupied and Unoccupied operation.

• Terminals included for connecting optional S963B1128 Remote Potentiometer for remote minimum damper position control.

• LED indicates when free cooling is available.

• LED indicates when module is in DCV mode.

• LED indicates when exhaust fan contact is closed.

• W7213 is used with heat pump B terminal.

• W7214 is used with heat pump O terminal.

IMPORTANT

Specifications given in this publication do not include normal manufacturing tolerances. Therefore, this unit may not exactly match the listed specifications. Also, this product is tested and calibrated under closely controlled conditions and some minor differences in performance can be expected if those conditions are changed.

When Installing this Product...

1. Read these instructions carefully. Failure to follow

them could damage the product or cause a hazardous condition.

2. Check the ratings given in the instructions and on the product to make sure the product is suitable for your application.

3. Installer must be a trained, experienced service technician.

4. After installation is complete, check out product operation as provided in these instructions.

Electrical Shock or Equipment Damage Hazard. Can shock individuals or short equipment circuitry.

Disconnect power supply before installation.

IMPORTANT

All wiring must agree with applicable codes, ordinances and regulations.

63-2576—02 2

C7046C DISCHARGE AIR SENSORS

)

(25)

)

)8 (

)

GASKET

)

USH

)

BUS

SENSO

OBE

)

(

)

SYSTEM

COMPO

(

)

SENSO

SYS

CONDU

CONDUIT

(

)

SYS

COMPO

(

)

SOLID STATE ECONOMIZER SYSTEM

Specifications

Intended for use as a discharge sensor in rooftop applications.

Dimensions: See Fig. 1.

Mounting: Mounting flange requiring two No. 8 screws.

Sensing Element: Carbon type, thermistor-resistor element.

Maximum Ambient Temperature: 250°F (121°C).

Operating Temperature Range: 40 to 150°F (4 to 66°C).

Wiring Connections: 6 in. (152 mm) leadwires.

Performance Characteristics:

Reaction Time Constant with Air Approach Velocity of

500 ft/min (2 m/sec): 60 seconds.

Resistance/Temperature (NTC):

Nominal Resistance: 3000 ohms at 77°F (25°C). Nominal Sensitivity: 70 ohms per degree F (124 ohms per

degree C) at midrange.

2 (51

1-1/2 (38

3/4 (19

203

PLASTI

HIN

1 (25

6 (152

1/16 (2

4. Fasten the sensor to the duct or plenum surface with two No. 8 sheet metal screws (not provided).

Mounting in a Junction Box (Fig. 3)

1. Cut a 3/8 in. (9.5 mm) hole in the duct or plenum

surface at the desired location.

2. Remove the center rear knockout from the junction box and insert the sensing probe through the knockout with the flange flat against the outlet box.

3. Using the flange as a template, mark and drill two holes in the junction box and the duct or plenum surface for No. 8 mounting screws.

4. Insert sensor probe through both the junction box knockout and the 3/8 in. (9.5 mm) hole drilled in the duct or plenum and fasten the junction box and sensor to the duct or plenum surface.

SYSTEM DUCT OR PLENUM

NO. 8 (4mm MOUNTING SCREW

NOT PROVIDED

FLAN

5/16 (9) DIAMETE

(BUSHING

LOCKING P

1/4 (6

NUTS (2

IAMETER (2 HOLES

NEOPRENE

M224

Fig. 1. C7046C Air Temperature Sensor dimensions

in in. (mm).

NOTE: Sensor probe diameter is 1/4 in. (6 mm).

Installation

The sensor assembly (see Fig. 1) consists of an aluminum sensor probe (element housed internally) with attached flange that can be mounted on a flat duct or plenum surface, or in a 2 in. by 4 in. (51 by 102 mm) junction box using two No. 8 screws. Connections to the sensor are made through two 6 in. (152 mm) leadwires.

LOCATION

The sensor should be located in the air duct or plenum where it will sample an average air temperature. Avoid locations where air stratification can cause sensing errors.

MOUNTING

Mounting on a Flat Duct or Plenum Surface (Fig. 2)

1. Cut a 3/8 in. (9.5 mm) hole in the duct or plenum

surface at the desired location.

2. Insert sensor probe into the duct or plenum until the flange rests against the duct or plenum wall.

3. If necessary, use the flange as a template to mark and drill two holes for No. 8 mounting screws.

T APPROPRIAT

NENT

M2240

Fig. 2. Mounting C7046 Air Temperature

Sensor on a flat duct or plenum surface.

FLAN

TANDARD UTILIT

IT B

NNECT

LOCKNUT

TO APPROPRIATE

TEM

NENT

TEM DUCT OR PLEN

PROB

NNECT SENSOR WIRE WITH TWO WIRENUT CONNECTORS

Fig. 3. Mounting C7046 Air Temperature

Sensor in a junction box.

NNECT SENSOR IRES WITH TW IRENUT CONNECTOR

NOT PROVIDED

NO. 8 (4mm) MOUNTING SCREWS (NOT

ROVIDED

FACEPLAT

OPTIONAL

NOT PROVIDED

3 63-2576—02

SOLID STATE ECONOMIZER SYSTEM

CAUTION

Wiring

Electrical Shock or Equipment Damage Hazard. Can shock individuals or short equipment circuitry.

Disconnect power supply before installation.

Erratic System Operation Hazard. Failure to follow proper wiring practices can introduce disruptive electrical interference (noise).

Keep wiring at least one foot away from large inductive

loads such as motors line starters, lighting ballasts, and large power distribution panels.

Shielded cable is required in installations where these

guidelines cannot be met.

Ground shield only to grounded controller case.

IMPORTANT

1. All wiring must agree with applicable codes, ordinances and regulations.

2. Do not mount sensor in incorrect environment.

3. Wire according to the applicable controller instructions.

4. Erratic temperature readings from a sensor can be caused by improper wiring practices. These must be avoided to assure proper operation:

•Avoid poor wiring connections.

•Avoid intermittent or missing building earth ground.

•Do not mount sensor in incorrect environment.

Connect low voltage wiring from the sensor to the appropriate system component terminals using solderless connectors. See Fig. 3.

Operation

The C7046C Air Temperature Sensors consist of a thermistor sensing element mounted in a tubular probe. They are applied at various locations throughout single zone and multizone duct systems. The negative temperature coefficient (NTC)

characteristic of the thermistor element causes its resistance to decrease as the sampled air temperature increases. This resistance shift is balanced with other system sensor signals by appropriate system logic panels to stabilize system control.

Checkout

Allow the C7046 Air Temperature Sensor to soak in the air moving through the duct or plenum for a minimum of five minutes before taking a resistance measurement.

1. Disconnect the sensor leadwires from the associated system components.

2. Connect an ohmmeter across the leadwires.

3. Assure nominal resistance measurements are in

accordance with the resistance/temperature curves shown in Fig. 4.

4. Reconnect sensor leadwires to associated system components.

5. Check operation of the complete control system.

17000

16000

15000

14000

13000

12000

11000

10000

9000

8000

7000

6000

RESISTANCE (OHMS)

5000

4000

3000

2000

1000

605040 70

0-10

TEMPERATURE (DEGREES)

2010

Fig. 4. C7046C Sensor resistance vs. temperature.

3,000 OHMS AT 77 F (25 C)

8010 20 30 90 100

30 35

25-5

M17969

63-2576—02 4

C7150B MIXED AIR SENSOR

)

1-1/2

(38)

(51)

3/4

(19)

3/4

(19)

2-3/8

(60)

2-1/4 (57)

M17992

C7150B1004 C7150B1046

SOLID STATE ECONOMIZER SYSTEM

Specifications

Models: See Table 1.

Dimensions: See Fig. 5.

Mounting Arrangement:

Integral mounting flange that requires No. 8 screws.

NOTE: The C7150B1004 requires four No. 8 screws;

the C7150B1046 requires two No. 8 screws.

Ambient Temperature Ratings:

Maximum: 250°F (121°C). Operating Range: -40 to 110°F (-40 to 43°C). Shipping Range: -30 to 150°F (-34 to 66°C).

Wiring Connection: 1/4 in. (6 mm) quick-connects.

NOTE: The C7150B1046 includes 4 in. lead wires with

connector for W7340 compatibility.

Table 1. C7150B Models.

Nominal Resistance

Model

at 77°F (25°C)

C7150B1004 3000 ohms 70 ohms per °F

C7150B1046 10K ohms 234 ohms per °F

Negative Temperature Coefficient (NTC).

Nominal Sensitivity

at midrange

(124 ohms per °C)

(415 ohms per °C)

Installation

1. Install on a mounting bracket (not included) inside the

2. Wire using 1/4 in. (6 mm) female quick-connect

DUCT

mixed air or discharge air duct using No. 8 mounting screws and nuts. (See Fig. 6).

NOTE: When mounting, ensure that terminals do not

touch metallic conductive surfaces.

terminated wires from C7150B to control inputs.

NOTE: For C7150B1046, splice additional wiring as

needed between sensor and connector.

NO. 8 MOUNTING SCREW

2 (51)

3/8 (9)

TO APPROPRIATE

SYSTEM SENSOR

1/2 (13)

INPUT

M17938A

Fig. 6. Mounting C7150B [C7150B1004 shown].

/16 (5) DIAMETE

2-1/2 (64

Fig. 5. C7150B approximate dimensions in in. (mm).

NOTE: Fig. 6 displays bracket (not included) and suggested

bracket dimensions in in. (mm).

Operation

The C7150B Air Temperature Sensor consists of a thermistor sensing element mounted on a phenolic board. It is applied in ventilation duct systems. The thermistor element negative temperature coefficient (NTC) characteristic causes its resistance to decrease as the sampled air temperature increases. This resistance change is used as a control system sensor to regulate discharge air temperature in a W973 Single Zone System or damper position of the M7215A Motor (either directly, or through the Economizer Logic Module).

Checkout

Allow the C7150B Sensor to soak in the air moving through the duct for a minimum of 5 minutes before taking a resistance measurement:

1. Disconnect sensor leadwires from associated system components.

2. Connect an ohmmeter across the leadwires.

3. Nominal resistance measurements should be in

accordance with the resistance/temperature curves shown in Fig. 7 and Fig. 8.

4. Reconnect sensor leadwires to associated system components.

5. Check operation of the M7215A Motor, W973 System, or the Economizer Logic Module.

5 63-2576—02

SOLID STATE ECONOMIZER SYSTEM

17000

16000

15000

14000

13000

12000

11000

10000

9000

8000

7000

6000

RESISTANCE (OHMS)

5000

4000

3000

2000

1000

605040 70

0-10

TEMPERATURE (DEGREES)

2010

3,000 OHMS AT 77 F (25 C)

8010 20 30 90 100

30 35

25-5

M17969

Fig. 7. C7150B1004 Sensor resistance temperature.

50000

45000

40000

35000

30000

25000

RESISTANCE (OHMS)

20000

15000

10000

5000

605040 70

TEMPERATURE (DEGREES)

2010

10,000 OHMS AT 77 F (25 C)

8020 30 90 100

30 35

25-5

M20071

Fig. 8. C7150B1046 Sensor resistance temperature.

63-2576—02 6

C7232 DCV SENSORS

CAUTION

SOLID STATE ECONOMIZER SYSTEM

Specifications

Models: C7232 Sensor and Controller. A stand-alone carbon

dioxide (CO

(one analog and one spst relay). C7232A: Wall mount model. C7232B: Duct mount model.

NOTE: Models are available with or without a 4-digit LCD

Dimensions:

C7232A: See Fig. 9. C7232B: See Fig. 10.

Sensor Performance Ratings:

Response Time: 2 min. Carbon Dioxide Sensor:

Operation: Non-dispersive infrared (NDIR).

Sampling: Diffusion.

Range: 0 to 2000 ppm ±5% and ±50 ppm.

Annual Drift: 20 ppm (nominal).

Electrical Ratings:

Power Supply: 24 Vac ±20%, 50/60 Hz (Class 2). Maximum Power Consumption: 3W. Peak Current (at 20 ms): 600 mA. Relay:

Configuration: Shipped N.O. (reconfigure with software.)

Contact Rating: 1A at 50 Vac/24 Vdc.

Minimum Permissible Load: 1 mA at 5 Vdc. Linear Analog Output:

Voltage: 0/2-10 Vdc (resistive load greater than

5000 ohms).

Current: 0/4-20 mA (resistive load less than 500 ohms).

Outputs (Jumper Adjustable, see Table 3):

Analog: 0-10 Vdc (Default: 2-10 Vdc, 500 to 1500 ppm). Relay: Normally Open Spst (Default: Close at 800 ppm).

) sensor with two jumper-adjustable outputs

that indicates the current CO

concentration.

Underwriters Laboratories Inc. Listed, File No. E4436. cUL. C7232B: Flammability Rating, UL94-5V. C7232A: NEMA1. C7232B: NEMA3.

(25)

5-1/16

(128)

3-5/32 (80)

KNOCKOUTS FOR EUROPEAN APPLICATIONS

2-3/8 (60)

STANDARD

2-3/8

(60)

MOUNTING

CONDUIT

Fig. 9. C7232A dimensions in in. (mm).

3-5/16 (84)

M17592

5-5/8 (142)

1-13/16

(46)

1-5/8

(41)

8 (203)

Fig. 10. C7232B dimensions in in. (mm).

Installation

UTILITY

BOX (2X4)

HOLES

M17540

Ambient Ratings:

Temperature:

Operating: +32°F to +122°F (0°C to +50°C).

Storage: -4°F to +158°F (-20°C to +70°C). Relative Humidity (non-condensing): 0 to 95 percent.

Pressure Dependence: 1.4% change in reading per

1 kPa deviation from 100 kPa.

Connections:

Wiring:

C7232A: 20-gauge cable with six 8 in. leadwires.

C7232B: 20-gauge cable with six 6 in. leadwires.

Mounting:

C7232A: Vertical surface with standard single-gang junction

box. C7232B: Sheet metal duct with a sampling tube.

Automatic Background Calibration (ABC) default: On.

Approvals:

CE.

Health Hazard. Improper use can create dangerous situations.

Use in application for sensing carbon dioxide only. For life-safety applications, this device can function only as a secondary or lesser device.

Electrical Shock or Equipment Damage Hazard. Can shock individuals or short equipment circuitry.

Disconnect power supply before installation.

Equipment Damage Hazard. Electrostatic discharge can short equipment circuitry.

Ensure that you are properly grounded before handling the unit.

7 63-2576—02

SOLID STATE ECONOMIZER SYSTEM

C7232A Cover Removal/Replacement

C7232A COVER REMOVAL (SEE FIG. 11)

1. Remove button head socket cap screw and set it aside.

2. Insert the head of a small screwdriver into the slot at the

center and near the top of the cover.

3. Gently pull the handle down toward the bottom of the device until a small gap between the subbase and the cover appears.

4. Remove the screwdriver and pull the cover straight down until it meets a stop.

5. Pull the cover straight off the subbase.

C7232A COVER REPLACEMENT

1. Feed the wires through the opening in the subbase.

2. Place the cover, with a small gap at the top, flat on top

of the subbase.

3. When the cover rests flat on the subbase, slide it straight up until it latches in place.

NOTE: When mounting on a junction box, see Fig. 12.

3. Replace the cover.

DUCT MOUNTING (SEE FIG. 13)

1. Place gasket on aspiration tube.

IMPORTANT

Ensure largest tab at tube control end is at the top.

2. Insert tube into duct; attach using screws and washers.

IMPORTANT

Leakage into the duct or the C7232 box cover from the room will skew the sensor readings. Ensure the box cover and duct seal completely.

3. Place o-ring on tube end; mount the control to the tube.

STANDARD UTILITY CONDUIT BOX

NO. 6 SCREW

FRONT COVER

BUTTON HEAD SOCKET CAP SCREW

M17541

ALLEN TOOL

Fig. 11. C7232A cover removal.

Location and Mounting

C7232 Sensors mount directly on the wall, sheet metal duct, or a panel. When planning the installation, allow enough clearance for maintenance and service. Mount the sensor in a well-ventilated area.

NOTES: Do not install the sensor where it can be affected by:

WALL MOUNTING

The C7232 Wall Mount models can be mounted using two or four screws:

— drafts or dead spots behind doors and in corners. — air from ducts.

1. Remove C7232 cover.

2. Mount the subbase to the wall using washers and two or

four screws (not supplied) appropriate for the wall material.

BUTTON HEAD SOCKET CAP SCREW

NO. 6 SCREW

Fig. 12. Junction box mounting (C7232A).

FLOW

Fig. 13. Duct mounting (C7232B).

SUBBASE

M17542

M17591

63-2576—02 8

SOLID STATE ECONOMIZER SYSTEM

CAUTION

L1 (HOT)

M17543

1 POWER SUPPLY. PROVIDE

DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

C7232

24V

YELLOW

BLACK

RED

BROWN

ORANGE

GREEN

ANALOG

OUT

–

Wiring

The factory ships the device with the output default settings shown in Table 3 and Table 4. Set the jumpers and wire the device (see Table 2 and Fig. 14).

Electrical Shock or Equipment Damage Hazard. Can shock individuals or short equipment circuitry.

Disconnect power supply before installation.

Equipment Damage Hazard. Electrostatic Discharge Can Short Equipment Circuitry.

Ensure that you are properly grounded before handling the unit.

IMPORTANT

1. All low voltage connections to this device must be 24 Vac Class 2.

2. All wiring must comply with applicable local codes, ordinances and regulations.

Table 2. C7232 Wiring Connections (see Fig. 14).

Wire Color Designation Function

Red G+ 24 Vac Hot

Black G0 24 Vac Common

Yellow OUT1 Analog Output Signal

Brown M Analog Output Common

Orange NO Relay Output Normally Open

Green COM Relay Output Common

Operation

Input Signal

The C7232 Sensors have an adjustable range. These ranges are determined by the SW1 and SW2 jumper settings (see Table 3).

Tab l e 3 . C O

SW1 SW2 AN (ppm) Relaya (ppm)

On On 0 to 1000 1000

On Off 0 to 2000 1200

Off

Off Off 500 to 2000 1200

When the level reaches this value, the contacts close; when the level drops 100 ppm below this value, the contacts open.

Setting when shipped from the factory.

Output Signal

The output signal can be adjusted for 0/2-10Vdc or 0/4-20mA (see Table 4).

Table 4. Output Signal Jumper Settings

Voltage 0-10Vdc 2-10Vdc

Current 0-20 mA 4-20 mA

NOTES:

— On duct models, remove the screw holding the

board in place to view jumper settings on reverse. (See Fig. 15.)

— The CO

are independent of each other. 0-100% and 20-100% are simply markings for the OUT jumper settings on the sensor (to differentiate between the two voltage and the two current ranges) and do not refer to or alter the ppm range chosen.

Range Jumper Settings

500 to 1500 800

OUT

0-100% 20-100%

settings and the output signal settings

Fig. 14. Wiring the C7232.

SW2SW1 OUT

OFF

20 – 100%

0 – 100%

Current

Voltage

M19424

Fig. 15. C7232 default jumper settings.

9 63-2576—02

SOLID STATE ECONOMIZER SYSTEM

Example

For a CO2 setting of 0-2000 ppm and a voltage output of 0-10 Vdc, the output would be as shown in Table 5 (arbitrary points along the analog curve).

Table 5. 0-10 Vdc Output Example.

Level (ppm)

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Voltage Output (Vdc)012345678910

For a CO along the analog curve).

setting of 0-2000 ppm and a voltage output of 2-10 Vdc, the output would be as shown in Table 6 (arbitrary points

Table 6. 2-10 Vdc Output Example.

Level (ppm)

0 250 500 750 1000 1250 1500 1750 2000

Voltage Output (Vdc) 2 3 4 5 6 7 8 9 10

Calibration

Typically, calibration is unnecessary. No calibration kits are available. However, if CO chamber using a general gas purge device, the sensor can be rezeroed:

gas can be purged from the sensor

Checkout

Perform a quick test of the unit with the unit powered:

1. Stand close to the unit and breathe air into the sensor.

2. Check the CO2 level registered by the controller to

ensure a strong rise.

3. When connected to a damper in a ventilation system,

IMPORTANT

Any CO zero level resulting in incorrect CO

present during calibration skews the sensor

level reports.

the controller typically signals an increase in air flow.

1. Once the sensor stabilizes, use a screwdriver to connect the two MENU soldering pads.

2. The display should indicate CAL.

3. Execute the zero calibration by connecting the two

ENTER soldering pads.

4. The display should return to providing the measured CO

level.

63-2576—02 10

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