Instructions / Assembly

ManualsBrandsTaco ManualsHeating, Ventilation, and Air Conditioning3/4 in. NPT 120-VAC Probe Low Water Cutoff Auto Reset

GENERAL

The Foam Compensating Low Water Cutoffs, (LF series), are

advanced, microprocessor based low water cutoffs for detecting the

presence of a conductive ﬂ uid in a vessel or tank. The LF series is

primarily designed for use in low-pressure steam and hot water boilers

to cutoff the burner in low water level conditions. They may be used as

either the primary or secondary cutoff on low-pressure steam boilers

or as the primary low water cutoff on hot water boilers. Additionally,

they can protect pumps from running dry in condensate receiver tank

applications or activate alarm systems or automatic water feeders. (See

each boiler manufacturers’ speciﬁ cations for recommended minimum

safe water levels.)

The LF series uses its DualVision technology to identify when its

probe is in foam and the boiler water is at an unsafe level. The LF

series cannot be fooled by the presence of conductive foam on its

probe, and it does not require periodic shutdowns of the boiler to

determine actual water levels in foaming boilers. The DualVision

technology also allows the LF series to identify reduced probe signal

levels due to fouling and turns on an LED light when the probe should

be inspected and cleaned. The LFA models automatically reset when

water levels return to safe levels. The LFA control may be used with an

alarm or with an automatic water feeder (EWF) to keep the boiler ﬁ lled

to the proper level. The LFM models are manual reset models. Once

a low water level has returned to proper levels, the reset switch on the

LFM must be pressed to restore the system to normal operation.

During a low water condition, the “STATUS” LED will illuminate RED. In

normal conditions, it will illuminate GREEN. If the LFA detects foaming,

the “SERVICE” LED will blink AMBER. If the LFA detects a low signal

level from the probe, the “SERVICE” LED will illuminate AMBER

to signal that probe cleaning may be required. (See Fig. 3 for LED

operation details).

The LF series will not lock out upon power loss provided water remains

covering the probe. They fully comply with CSD-1 requirements.

US Patents 6,904,800,

7,243,540, and 7,317,993

Other Patents Pending

Instruction Sheet

Foam Compensating Low Water Cutoff with

Test Button and DualVision™Technology

102-207

SUPERSEDES: REVISION G DATED December 22, 2008

#5401163-REV H PLANT ID 001-3908

EFFECTIVE: April 27, 2009

Contact Ratings

Voltage

Motor Switch Rating

Pilot Rating

Full Load Locked Rotor

24 VAC - - 50 VA

120 VAC 7.5 A 43.2 A 125 VA

240 VAC 3.75 A 21.6 A 50 or 60 Hz

Listings/Approvals:

• UL GUIDE (MBPR) for Limit Controls per UL Standard 353 Limit

Controls

• UL GUIDE (MCUR2) for Electrode Assemblies - Component

• CUL per CSA Standard C22.2 No.205-M1983

• FM Approved (For applications with a supervised burner

management system)

• Fully compliant with CSD-1 requirements

Probe Fitting Thread: 3/4” NPT

Enclosures:

Control Unit – NEMA Type 1 (For indoor use only.) Formed sheet

metal with powder coat/plated ﬁ nish. Five openings for 1/2” conduit

ﬁ ttings.

Maximum Pressures: Steam - 250 psi (17.6kg/cm

)

Hot Water - 250 psi (17.6kg/cm

)

Maximum Probe Temperature: 250° F (121° C)

Maximum Ambient Temperature: 150° F (66° C)

Delays: Delay on Make, (DOM), and Delay on Break, (DOB),

automatically provided based upon boiler conditions.

Foam Compensating: The DualVision technology provides

continuous protection against false water level detection due to

probe being in foam. Automatic detection of foaming conditions

and shutdown of boiler when water level becomes unsafe.

Eliminates intermittent shutdown of the boiler.

Probe Sensitivity: Extended operation to 20K Ohms,

Service range 20K to 40K Ohms

Input Supply Voltage:

Input Voltage Power Consumption

120 VAC 3 VA

24 VAC** 3 VA

** 24VAC to be supplied by

an EXTERNAL Class 2 power

source.

• Installation must be performed by qualiﬁ ed personnel and in accordance with all national and local codes and ordinances.

• Read all instructions carefully and understand them before starting installation. Save instructions for future use.

• Instruct user how to test and operate this cutoff device as described in these instructions.

• Shock Hazard. Disconnect power source before servicing. Serious injury or death could result.

• Risk of explosion. Not for use in hazardous locations. Serious injury or death could result.

• The LWCO device must be installed in series ahead of other limit and operating controls installed on the boiler. When installations are complete,

check for correct operation of ALL limit and operating controls.

• Wire insulation must be rated at 167º F (75º C) or greater, over copper conductors only. Use of other wire or insulation types could result in ﬁ re

causing property damage, serious injury, and death.

• Foam in boiler or piping can cause improper operation. If the boiler is foaming, shutdown the boiler and clean it per the manufacturers

recommendations to eliminate foaming. Failure to do so could result in damage to the equipment and property or could cause an explosion resulting

in serious injury or death.

• Use only the probe that is supplied with this control or replacement probe P3S-1. Failure to do so could result in improper operation, damage to the

equipment and property, or could cause an explosion resulting in serious injury or death.

• Hot or pressurized boiler systems can discharge steam and hot water. Cool boiler system to 80º F (27º C) and to 0 psi (0 bar) before servicing.

Failure to do so could result in serious burns.

Summary of content (6 pages)

PAGE 1
Instruction Sheet Foam Compensating Low Water Cutoff with Test Button and DualVision™Technology SUPERSEDES: REVISION G DATED December 22, 2008 #5401163-REV H PLANT ID 001-3908 102-207 EFFECTIVE: April 27, 2009 Listings/Approvals: • UL GUIDE (MBPR) for Limit Controls per UL Standard 353 Limit Controls • UL GUIDE (MCUR2) for Electrode Assemblies - Component • CUL per CSA Standard C22.2 No.
PAGE 2
• Do not tighten by grasping the device enclosure. Use wrenching flats on the probe bushing only. Failure to install properly could damage the device and cause improper operation resulting in damage to equipment and property. • Do not use manual reset low water cutoffs with automatic water feeders. Flooding, equipment damage, and property damage can result. Only use automatic water feeders with automatic reset low water cutoffs. PROBE SPACING REQUIREMENTS FIG. 1 CONTROL UNIT MOUNTED ON PROBE FIG.
PAGE 3
LWCO WIRING DIAGRAM USING BURNER CIRCUIT POWER SOURCE FIG. 5 LWCO WIRING DIAGRAM USING TERMINAL BLOCK CONNECTIONS POWER SOURCE OTHER THAN CLAMPING PLATE TERMINAL BURNER CIRCUIT FIG. 7 FIG. 6 Wire insulation must be rated at 167º F (75º C) or greater. Use at least 18 AWG copper conductors, or as required by code. Use of other wire or insulation types could result in fire causing property damage or serious injury. Note: Remote probe available on remote probe models only.
PAGE 4
Test For Proper Function: 1. DO NOT fill boiler. Set thermostat to lowest possible setting and turn on electric power to the boiler. On initial start-up, the LWCO indicates low water condition, which indicates proper function. The "STATUS" LED on the control unit illuminates RED. The burner should not operate without water in the system. During the testing process, the "SERVICE" LED should not be illuminated. 2. Fill boiler with water.
PAGE 5
LWCO Ordering L F A 1 2 0 3 S 1 Revision Probe Styles S - Standard R - Remote Probe w/ NEMA 4 Enclosure 1 - 12” Long Electrode (Remote, NEMA 4 Style) 2 - 24” Long Electrode (Remote, NEMA 4 Style) Process Connection 3 - 3/4” NPT 2 - 1/2” NPT Input Power 024 - 24VAC 120 - 120VAC Reset Type A - Automatic Reset M - Manual Reset Probe Only Ordering F - Foam Compensating-Testable P 3 S Low Water Cutoff 1 Revision Probe Styles S - Standard R - Remote Probe w/ NEMA 4 Enclosure 1 - 12” Long Electrode (Remote,
PAGE 6
Limited Warranty Statement Taco, Inc. will repair or replace without charge (at the company’s option) any product or part which is proven defective under normal use within one (1) year from the date of start-up or one (1) year and six (6) months from date of shipment (whichever occurs first).