Honeywell L7124U Installation Instructions Manual

Page 1

L7124U Universal Oil

Electronic Aquastat® Controller

INSTALLATION INSTRUCTIONS

APPLICATION

The L7124U Universal Oil Electronic Aquastat® Controller provides electronic temperature sensing in a UL limit-rated control with a single sensing probe. The L7124U controls circulator, oil burner and boiler temperature. The L7124U replaces the L8124A, L8124C and L8148A Controllers.

General

The L7124U Universal Oil Electronic Aquastat® Controller is a primary safety limit-rated device designed for use with oil fired boilers with line voltage burners and circulators. The boilers do not include wiring or control compartments as part of the design, but are provided with an integral, replaceable, immersion well that is the mounting hardware for the L7124U. Wiring to the other controls is done through flexible metal conduit. A separate electromechanical high-limit is not required in a system that uses this control.

A manually-adjusted potentiometer is used to set the High Limit. The overall range of the High Limit dial is from 130°F to 240°F (54°C to 116°C). The High Limit is calibrated for accuracy at 212°F (100°C). Some models have limited ranges on the high limit setpoint; this limited range is listed on the device label, but the potentiometer travels the full mechanical distance.

Some models also have a Low Limit and Low Limit Differential adjustment. The range of the Low Limit dial is from 110°F to 220°F (43°C to 104°C). Rotating the Low Limit potentiometer fully counterclockwise disables the low limit function and turns on the Low Limit Disabled LED.

The L7124U is designed for use with 24 Vac electronic and electromechanical thermostats and has screw-type terminals for easy field connection.

SPECIFICATIONS

Electrical Ratings:

Voltage: 120 Vac, 60 Hz. Power: 10 VA maximum at 120 Vac plus external loads. Thermostat current: 100 mA nominal at 24 Vac. Burner Relay:

7.4A at 120 Vac Full Load Amperage (FLA);

44.4A inrush Locked Rotor Amperage (LRA); Plus Ignition Load: 360 VA.

Circulator Relay:

7.4A at 120 Vac FLA; 44.4A inrush LRA. Zone Controller (ZC): 7.4A at 120 Vac FLA;

44.4A inrush LRA.

Differential Ratings:

High Limit Differential: 15°F subtractive. Low Limit Differential: Adjustable 10°F to 25°F

subtractive from Low Limit setpoint.

Environmental Ratings:

Temperature: -30°F to +150°F (-34°C to +66°C). Humidity: 0 to 95% relative humidity, noncondensing.

Approvals:

Underwriters Laboratories Inc. Component Recognized:

Pending approval.

Canadian Underwriters Laboratories Inc. Component

Recognized: Pending approval.

Accessories

Accessories (Ordered Separately):

120650 Heat Conductive Compound 124904 Well Adapter 32002190-001 Relay 32004955-001 Sensor 4074GYZ Fuse, 1A (10-pack package)

Table 1. Wells for L7124U Controller.

Part

Number

123869A 1/2 NPT 3 1-1/2

123870A 3/4 NPT 3 1-1/2

Spud Size

(in.)

Insertion

(in.)

Insulation

(in.)

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L7124U UNIVERSAL OIL ELECTRONIC AQUASTAT® CONTROLLER

INSTALLATION

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. The installer must be a trained, experienced service technician.

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

WARNING

Electrical Shock Hazard. Can cause serious injury or death.

Disconnect power supply before beginning installation to prevent electrical shock or equipment damage.

Mounting

The L7124U has a case that can be converted for either horizontal or vertical mounting. See Fig. 1.

IMPORTANT

Immersion well must fit sensing element and sensor bulb must rest against bottom of well.

New Installation

Order well assemblies for the L7124U separately; see form 68-0040, Wells and Fittings for Temperature Controllers. Boilers usually have tappings that allow the well to be mounted horizontally so boiler water of average temperature can circulate freely.

1. Turn off all power and drain the boiler.

2. If no tapping is provided, prepare properly sized

and threaded tapping near the top of the boiler.

3. Sparingly coat the well threads with pipe dope.

BRACKET POSITION FOR VERTICAL MOUNTING

BRACKET POSITION FOR HORIZONTAL MOUNTING

M8890

Fig. 1. Case designed for vertical

or horizontal mounting.

69-1232—2 2

NOTE: Do not attempt to tighten by using the case as a

handle.

4. Install the well in the boiler tapping and tighten securely.

5. Refill boiler and check for water leakage.

6. Loosen but do not remove the clamp screw on the

L7124U case.

7. Insert the sensor element into the well until it bottoms. (If necessary, slightly bend the tube inside the case to hold the sensor against the bottom of the well.)

NOTE: Some models have an adjustable wire length to

3 in. (76 mm). For these models, pull out extra wire length from inside the case, if needed.

8. Fit the case into the well so the clamp on the case slides over the flange on the well.

9. Securely tighten the clamp screw.

IMPORTANT

Best thermal response is obtained with a well that snugly fits the sensor. Insert the sensor until it rests against the bottom of the well. use a well of correct length and bend the wiring, if necessary, to hold the bulb against the bottom of the well.

If the well is not a snug fit on the sensor, use the heat-conductive compound (furnished with TRADELINE models) as follows: Fold the plastic bag of compound lengthwise and twist it gently. Then snip off end of bag and work the open end of the bag all the way into the well.

Slowly pull out the bag while squeezing it firmly to distribute compound evenly in the well. Bend the wiring, if necessary, to hold the sensor against the bottom of the well and to hold outer end of the sensor in firm contact with the side of the well. See Fig. 2. Wipe excess compound from the outer end of the well.

Replacement Installation

Turn off all power and remove the old control. Refer to the cover insert of the old control to identify and tag each external lead as it is disconnected. If the old well is unsuitable for the new installation, remove it and proceed with instructions for new installation. If the old well is suitable, use it and an immersion well adapter (ordered separately) for the installation. (The well clamp may fit directly over the flange of the existing well spud and using the adapter may not be necessary.) The adapter has a flange at the wide end that fits into the well clamp and is slotted lengthwise to accommodate the sensor wire.

1. Loosen but do not remove the well clamp screw on the side of the control case.

2. Pull out the wire until the sensor bottoms in the well. Place adapter, if used, around the sensor wire so it fits into the slot. See Fig. 2.

3. Make sure the wide end of the adapter fits into the hole in the case. Position immersion well clamp snugly over the flange of the adapter and tighten the clamp screw.

4. Insert the sensor into the well as shown in Fig. 2. (Distribute the heat-conductive compound in the tube prior to bulb insertion.)

5. Securely tighten the setscrew against the adapter.

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L7124U UNIVERSAL OIL ELECTRONIC AQUASTAT® CONTROLLER

SENSOR WIRES

CONTROLLER CASE

IMMERSION WELL CLAMP

IMMERSION WELL CLAMP SCREW

BOILER

IMMERSION WELL

HEAT-CONDUCTIVE COMPOUND (OPTIONAL)

SENSOR

M16120

Fig. 2. Position of sensor in immersion well.

WIRING

WARNING

Electrical Shock Hazard. Can cause serious injury or death.

Disconnect power supply before making wiring connections to prevent electrical shock or equipment damage.

All wiring must comply with local electrical codes and ordinances. Do not exceed the specifications in the Application section when wiring this control.

IMPORTANT

The terminals on these Aquastat® Controllers are approved for use with copper wire only.

Follow the appropriate wiring diagrams shown on the inside of the front cover of the L7124U or in Fig. 3 and 4.

LINE VOLTAGE CIRCULATOR

SENSOR

L1 (HOT)

PWR

SENSOR

2 1

F01

LOW VOLTAGE THERMOSTAT

TL2T TSTAT

HIGH LIMIT

DIFF.

LOW LIMIT

DSBL

LINE VOLTAGE OIL BURNER RELAY

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

CONTROL CASE MUST BE CONNECTED TO EARTH GROUND. USE GROUNDING SCREW PROVIDED.

LEGEND: = LED

M17776

Fig. 3. L7124U single zone connections.

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L7124U UNIVERSAL OIL ELECTRONIC AQUASTAT® CONTROLLER

TO ADDITIONAL R845A

L B

SENSOR

LINE VOLTAGE CIRCULATOR

INE VOLTAGE OIL URNER RELAY

PWR

F01

SENSOR

2 1

LOW VOLTAGE THERMOSTAT

TL2T TSTAT

HIGH LIMIT

DIFF.

LOW LIMIT

DSBL

RELAYS FOR OTHER ZONES

L1 (HOT) L2

LEGEND: = LED

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

CONTROL CASE MUST BE CONNECTED TO EARTH GROUND. USE GROUNDING SCREW PROVIDED.

Fig. 4. L7124U multizone system with circulator connections.

R845A RELAY ZONE 2

ZONE 2

LOW VOLTAGE

THERMOSTAT

ZONE 2 CIRCULATO

M17777

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OPERATION

L7124U UNIVERSAL OIL ELECTRONIC AQUASTAT® CONTROLLER

High Limit Controller

The high limit opens and turns off the burner when the water temperature reaches the setpoint. The high limit automatically resets after the water temperature drops past the setpoint and through the 15°F (8°C) differential.

Low Limit and Circulator Controller

On a temperature rise, with the adjustable differential at the minimum setting of 10°F (6°C), the burner circuit breaks and the circulator circuit makes at the low limit setpoint. On a temperature drop of 10°F (6°C) below the low limit setpoint, the burner circuit makes and the circulator circuit breaks. See Fig. 5.

CAUTION

Equipment Damage Hazard. Can cause improper operation

1. Setting the Low Limit above the High Limit disables the device.

2. Setting the Low Limit less than 15°F (8°C) below the High Limit results in improper circulator function.

SWITCH BREAKS ON TEMPERATURE RISE.

HIGH LIMIT SETTING

LOW LIMIT SETTING

WHEN WATER REACHES LOW LIMIT SETTING, THE BURNER SHUTS OFF OR THE CIRCULATOR PUMP STARTS (WHEN CALLING FOR HEAT

Fig. 5. Setpoints and differentials.

BURNER TURNS OFF. CIRCULATOR OPERATES ON A CALL FOR HEAT.

SWITCH MAKES ON TEMPERATURE FALL. BURNER OPERATES ON A CALL FOR HEAT.

WITH NO HEATING DEMAND, SWITCH BREAKS ON TEMPERATURE RISE.

SWITCH MAKES ON TEMPERATURE FALL, BURNER IS ON TO MAINTAIN MINIMUM WATER TEMPERATURE. CIRCULATOR IS OFF.

M21059

The L7124U can be in any of four operational states: Normal, High-Limit, Low-Limit and Error. The controller moves back and forth from High-Limit to Normal to Low-Limit state as part of normal operation. However, the controller enters only the Error state when there is an abnormal condition such as an internal error or a bad sensor. The operating states are:

1. Normal: Boiler temperature has gone below the high limit setting (minus the fixed differential) and has not exceeded the high limit setting; or, the boiler temperature has gone above the low limit setting and has not gone below the low limit setting (minus the fixed differential).

2. High-Limit: Boiler temperature has gone above the high limit setting and has not dropped below the high limit setting (minus the fixed differential).

3. Low-Limit: Boiler temperature has gone below the low limit setting (minus the low limit differential) and has not gone above the low limit setting.

4. Error: The controller has detected an error condition (e.g., open sensor) and has shut down the burner output. The circulator and ZC output are energized. The controller continues to function and automatically restarts if the error condition clears.

The operating sequence for the L7124U is shown in Table 2.

CHECKOUT

Put the system into operation and observe operation through at least one complete cycle to make sure that the controller operates properly.

Table 2. L7124U Controller Operating Sequence.

Action System Response

Thermostat calls for heat.

Boiler exceeds the high limit.

Thermostat is satisfied.

Error condition.

Circulator starts when water temperature is above low limit setting (if applicable). Boiler temperature is checked. Burner starts when water temperature is below high limit setting and above low limit setting.

Burner is turned off. Burner restarts when the water temperature drops below the high limit setting minus the differential.

Circulator and burner turn off.

When an error condition is detected, all outputs except C and ZC are shut down. Burner is off. Control continues to function and restarts when error is corrected. During the error check sequence, the system checks for drift in the sensor and corrosion in the connections.

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L7124U UNIVERSAL OIL ELECTRONIC AQUASTAT® CONTROLLER

TROUBLESHOOTING

When attempting to diagnose system performance, references to the LED can help to identify specific areas not working properly. The LED are:

PWR—ON indicates 24 Vac power present.

C—ON indicates circulator relay energized.

TSTAT—ON indicates thermostat call for heat.

ZC—ON indicates power to zoning.

B—ON indicates burner relay energized.

LL/DSBL—

Table 4. Corrective Action .

System Condition Check Corrective Action

Boiler is cold, house is cold. PWR LED Off Check:

PWR LED On TSTAT LED Off

PWR LED On TSTAT LED On B (burner) LED On

PWR LED On TSTAT LED On LL/DSBL LED Flashing

Boiler is hot, house is cold. PWR LED On

TSTAT LED On C (circulator) LED On

PWR LED On TSTAT LED On C (circulator), ZC (zone circulator) LED Off

PWR LED On TSTAT LED On ZC LED on

• ON indicates Low Limit function selected.

• OFF indicates Low Limit disabled.

• Flashing indicates error. See Table 3 and Troubleshooting Guide, Table 4.

Table 3. LED Error Codes.

Number

of Blinks Cause

2 Sensor Error (Open or shorted sensor.)

3 System error(s); e.g., setpoint POT failure.

4 Safety relay has welded, device requires

replacement.

— 120 Vac system power. — 1A fuse on L7124U.

Check:

— Thermostat — Thermostat wiring

—Check: —120 Vac B1-B2. — If no, replace burner relay. — If yes, check burner and wiring.

Refer to LED diagnostics, Table 3.

Check:

— 120 Vac, C1-C2. — If no, replace circulator relay. — Check for circulation, air entrap-

ment, water flow. — If yes, check circulator and wiring. — Check for circulation, air entrap-

ment, water flow.

Check:

— Boiler below low limit temperature,

wait for boiler to above low limit

temperature.

Check:

— Boiler above low limit. — If yes, check for 120 Vac between

ZC and L2. — If no, replace ZC relay . — If yes, check switch relays, zone

circulators and wiring.

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