Xylem MM 206F User Manual

Download

Series 63 Low Water Cut-Off

Typical Applications:

- Primary or secondary low water cut-off for hot water and steam boilers.

- Low water cut-off

- High water cut-off

- Alarm actuator

OPERATION

Maximum Boiler Pressure: 50 psi (3.5 kg/cm2)

Electrical Ratings

Motor Switch Rating (Amperes)

Voltage

120 VAC 10.2 240 VAC 5.1 30.6

Full Load Locked Rotor

61.2 125 VA at

Pilot Duty

120 or 240 VAC

INSTRUCTION MANUAL

MM-206F

CUT OFF

LEVEL

Model 63

WARNING

CAUTION

WARNING

• Before using this product read and understand instructions.

• Save these instructions for future reference.

• All work must be performed by qualified personnel trained in the proper application, installation, and maintenance of plumbing, steam, and electrical equipment and/or systems in accordance with all applicable codes and ordinances.

• To prevent serious burns, the boiler must be cooled to 80˚F (27˚C) and the pressure must be 0 psi (0 bar) before servicing.

To prevent electrical shock, turn off the electrical power before making electrical connections.

•

• This low water cut-off must be installed in series with all other limit and operating controls installed on the boiler. After installation, check for proper operation of all of the limit and operating controls, before leaving the site.

• We recommend that secondary (redundant) Low Water Cut-Off controls be installed on all steam boilers with heat input greater than 400,000 BTU/hour or operating above 15 psi of steam pressure. At least two controls should be connected in series with the burner control circuit to provide safety redundancy protection should the boiler experience a low water condition. Moreover, at each annual outage, the low water cut-offs should be dismantled, inspected, cleaned, and checked for proper calibration and performance.

• To prevent serious personal injury from steam blow down, connect a drain pipe to the control opening to avoid exposure to steam discharge.

• To prevent a fire, do not use this low water cut-off to switch currents over 10.2A, 1/2 Hp at 120 VAC or 5.1A, 1/2 Hp at 240 VAC, unless a starter or relay is used in conjunction with it.

California Proposition 65 warning! This product contains chemicals known to the

•

state of California to cause cancer and birth defects or other reproductive harm. Previous controls should never be installed on a new system. Always install new

•

controls on a new boiler or system.

Failure to follow this warning could cause property damage, personal inj ury or death.

CAUTION:

•



A more frequent replacement interval may be necessary based on the condition of the unit at time of inspection. McDonnell Miller s warranty is one (1) year from date of installation or two (2) years from the date of manufacture.

Gauge Glass Mounted

Directly into Boiler

CUT-OFF LEVEL

1" BLOW DOWN

VALVE

For Boilers with

Independent Water Columns

1" STEAM

EQUALIZING PIPE

MODEL 63 LOW WATER CUT-OFF

1" WATER

EQUALIZING PIPE

1" WATER

EQUALIZING PIPE

1" WATER

EQUALIZING PIPE

CUT-OFF LEVEL

MODEL 63 LOW WATER CUT-OFF

a. Whether the gauge glass is mounted directly into the boiler or on an independent water column, the

cut-off line on the 63 body casting should be mounted 1/2” (15mm) above the lowest visible point of the gauge glass.

a. Locate the gauge glass and

determine the level that the 63 has to be mounted at in order to achieve the criteria in Step 1.

b. Pipe the 63 following the

diagrams shown to the right. Follow the diagram that represents your boiler.

c. Crosses should be used at

each right angle connection for inspection and cleaning.

d. Make sure the blow-down

valves are full port.

e. While the burner is operating,

open the blow-down valve, causing the water level to drop in the float chamber while burner is operating. As the float drops the alarm circuit (if used) closes first; then on further drop the cut-off circuit will open, shutting the burner off.

f. Test the Model 63 before leaving

the site.

STEP 2 - Installation of the Model 63

Model 63 – For Steam Boilers with 1” (25mm) Equalizing Lines

INSTALLATION –

TOOLS NEEDED:

One (1) flathead screwdriver and two (2) pipe wrenches.

STEP 1 - Determine the Location of the Low Water Cut-Off

For 63 models with float block

CUT OFF

LEVEL

Using pipe wrench

• Remove float blocking plug (A) from low water cut-off body tapping.

• Screw 3/4” NPT steel plug (provided) in tapping.

a. The line on the casting of the model 63 must be installed above the lowest permissible water level

determined by the boiler manufacturer.

a. Study the figures to the right and determine which

figure shows how the 63 control will be attached to the boiler.

Figure 1. Connect the upper equalizing pipe to the riser going to the radiation or to the compression tank. Connect the lower equalizing pipe to any available opening in the side of the boiler. NOTE: If no opening is available in the side of the boiler, connect the lower equalizing pipe into the drain connection.

Figure 2. If there is a tapping available on the top of the boiler, connect the upper equalizing pipe to it. NOTE: During initial filling or after blow-down the upper equalizing pipe and possibly the 63 control will have an air pocket. Connect a vent or bleed valve on the top of the vertical equalizing pipe. If the Test-NCheck (TC-4) valve is used the vacuum breaker can be used to bleed the air pocket. CAUTION: When bleeding an air pocket manually, protect yourself from being burned with hot water.

Figure 3. If there is no tapping available on the boiler, connect both the upper and lower equalizing pipe into the vertical riser going to the radiation or to the compression tank. IMPORTANT: The horizontal equalizing pipe should be below the horizontal run going to the radiation. If it is not, an air pocket will be created and a vent or bleed will have to be installed.

While the burner is operating open the blow-down valve, causing the water level to drop in the float chamber. As the float drops the alarm circuit (if used) closes first; then on further drop the cut-off circuit will open, shutting the burner off.

c. Test the Model 63 before leaving the site.

STEP 2 - Installation of the Model 63

Model 63 – For Hot Water Boilers with 1” (25mm) Equalizing Lines

INSTALLATION –

TOOLS NEEDED: One (1) flathead screwdriver and two (2) pipe wrenches.

For float type controls it is recommended that Test-N-Check

(TC-4) valves be used in the upper and lower equalizing lines. They offer a functional means for testing the 63 control, and conform to the ASME CSD-1 code.

STEP 1 - Determine the Location of the Low Water Cut-Off

VERTICAL RISER TO RADIATION

HOT WATER

BOILER

MODEL

Figure 1

Figure 2

Figure 3

For 63 models with float block

CUT OFF

LEVEL

Using pipe wrench

• Remove float blocking plug (A) from low water cut-off body tapping.

• Screw 3/4” NPT steel plug (provided) in tapping (A).

VERTICAL RISER TO RADIATION OR COMPRESSION TANK

TC-4

AVAILABLE OPENING IN TOP BOILER

AIR VENT

HOT WATER BOILER

MODEL

HOT WATER BOILER

MODEL

TC-4

1. Assemble the TC-U (the upper Test-N-Check

valves, with the vacuum breaker) into the upper equalizing line in place of the cross described in the low water cut-off installation instructions. NOTE: The vacuum breaker must be on the top and the long leg must face the boiler. NOTE: Make sure low water cut-off position is located in accordance with the boiler manufacturer’s recommended cut-off level.

2. Assemble the TC-L (the lower Test-N-Check

valve, without the vacuum breaker) into the lower equalizing line in place of the cross described in the low water cut-off installation instructions. NOTE: The brass cap must be located above the center of the lower equalizing line, and the long leg must face the boiler.

3. Assemble the blow-off valve into the bottom

port of the TC-L.

4. Assemble 1” NPT pipe plugs into the remaining

open port in both the TC-U and TC-L.

5. Complete the installation as described in the

low water cut-off installation instructions.

6. After all piping assembly has been completed,

refill the system with water, turn on all electrical supply and bring system to operating conditions. After system reaches operating pressure, inspect to make sure no leaks exist at the threaded connections. Test valves by opening blow-off valve while burner is on, to make sure valves operate correctly and low water cut-off shuts burner off.

Simplify Testing of Low Water Cut-offs on Hot Water Boilers

TEST-N-CHECK®VALVES

Installation of the TC-4 Test-N-Check valves with a New Low Water Cut-off

IMPORTANT:

• Installation should be performed by qualified personnel only, in accordance with all applicable codes.

• If vacuum breaker stem is accidentally depressed, hot water could be discharged causing burns.

• Blow-off valve drain piping should be piped to a suitable drain to handle hot water and steam discharge, and should be the same size as the equalizing pipe.

REMOVE CROSS

TC-U in Place

LWCO

TC-L

in Place

Brass Cap

Blow-off Valve

ELECTRICAL WIRING

TOOLS NEEDED:

One (1) flathead screwdriver.

Conduit opening facing toward float chamber

Conduit opening facing away from float chamber

Manual reset button on No. 2m Switch

a. The No. 2 switch can be positioned with the conduit opening

facing toward or away from the float chamber. These are the only positions in which the switch will function properly. See drawing at right.

b. On initial fill-up, push the 2M manual reset button after the

proper water level is reached to energize the burner. If a low water condition occurs and the water level has been restored, push the reset button to energize the burner.

c. Follow the wiring diagrams below to wire the No. 2 Switch.

Terminals C and NC are the low water cut-off switch. Terminals C and NO are alarm switch. If the electrical load exceeds the rating of the switch, use an auxiliary relay or motor starter.

USED AS A MAIN LINE SWITCH AND/OR LOW WATER ALARM

USED AS A PILOT SWITCH TO COIL OF RELAY OR MOTOR STARTER

N.C.

N. O.

N.C.

Neutral

120 V.A.C.

Supply Hot

Low Water Alarm

Burner Circuit

Line

Load

SCHEMATIC OF SWITCH OPERATION

Water Level Normal Burner On Alarm Off

Low Water Alarm Terminals

Low Water Cut-Off Terminals

N.O. N.C.

Water Level Low

Burner Off

Alarm On

N.O.

N.C.

• To prevent electrical shock, turn off the electrical power before making electrical connections.

Failure to follow this warning could cause electrical shock, an explosion and/or a fire, which could result in property damage, personal injury or death.

WARNING

Cover Removal and Installation Procedure

• Using a flathead screwdriver, remove the one (1) screw that secures the switch cover.

• Place the cover on the switch housing and, using a flathead screwdriver, tighten the one (1) screw to approximately 2 ft•lb (2.6 N•m).

Do not use automatic water feeders with manual reset LWCO’s.

Failure to follow this warning could cause flooding, property damage, personal injury or death.

WARNING

TROUBLESHOOTING

TESTING

Problem:

1. Burner does not shut off on low water.

a. Cause: Float chamber is loaded with mud or

sediment.

Test: With water level below the control

check if terminals C and N.C. are open. If not, remove switch and manually test if terminals C and N.C. can be opened.

Solution: Open float chamber and clean. At this

time, check for a build-up of scale or sediment between corrugations of the bellows.

b. Cause: Contacts are fused together.

Test: Remove switch and operate manually to

verify proper switch operation.

Solution: Replace switch. Check electrical load

and make sure it is within the ratings of the switch.

CUT OFF

LEVEL

TEST OPENING

• Control can be tested on a hot water boiler by gently inserting a screwdriver or similar tool in the test opening below the switch (see drawing) and lifting linkage to cause float to drop, thereby simulating a low water condition.

MAINTENANCE

SCHEDULE:

• Blow down control as follows when boiler is in operation:

Steam:

– Daily if operating pressure is above 15 psi. – Weekly if operating pressure is below 15 psi.

Hot Water:

– Quarterly

• Disassemble and inspect annually. Replace the low water cut-off if it is worn, corroded, or if components no longer operate properly.

• Inspect the float chamber and equalizing piping annually. Remove all sediment and debris.

• Replace head mechanism every 5 years.

More frequent replacement may be required when severe conditions exist such as rapid switch cycling, surging water levels, and use of water treatment chemicals.

• We recommend head mechanism replacement

when the switch(es) no longer operate properly.

If you choose to replace the switch(es), order the proper McDonnell & Miller replacement switch or switch assembly and follow the Repair Procedure provided.

More frequent blow-down may be necessary due to dirty water and/or local codes.

NOTE

PROCEDURE:

1. Blow down the low water cut-off when the water level is at its normal level and the burner is on. Slowly open the blow down valve until it is fully open and observe the water level fall in the gauge glass. Close the valve after verifying that the pump contacts have closed and the burner shuts off. If this does not happen, immediately shut off the boiler and correct the problem.

To prevent serious personal injury from steam pipe blow down, connect a drain pipe to the control opening to avoid exposure to steam discharge.

Failure to follow this caution could cause personal injury.

CAUTION

Xylem

1) The tissue in plants that brings water upward from the roots;

2) a leading global water technology company.

We’re 12,500 people uniﬁed in a common purpose: creating innovative solutions to meet our world’s water needs. Developing new technologies that will improve the way water is used, conserved, and re-used in the future is central to our work. We move, treat, analyze, and return water to the environment, and we help people use water efﬁciently, in their homes, buildings, factories and farms. In more than 150 countries, we have strong, long-standing relationships with customers who know us for our powerful combination of leading product brands and applications expertise, backed by a legacy of innovation.

For more information on how Xylem can help you, go to www.xyleminc.com

Xylem Inc.

8200 N. Austin Avenue Morton Grove, Illinois 60053 Phone: (847) 966-3700 Fax: (847) 965-8379 www.xyleminc.com/brands/mcdonnellmiller

McDonnell & Miller is a trademark of Xylem Inc. or one of its subsidiaries.

Xylem MM 206F User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual