Xylem MM 200G User Manual

Series 64 Low Water Cut-Off

INSTRUCTION MANUAL

MM-200G

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 Full Load Locked Rotor Pilot Duty

120 VAC 240 VAC

7.4

3.7

NOTE: 11MV is rated 24VA @ 24VAC to 120VAC.

ION

ING

• 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, instal-

lation, 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 7.4A, 1/3 Hp at 120 VAC or 3.7A, 1/3 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.

44.4

22.2

120 VA at

120 or 240 VAC

CUT-OFF

LEVEL

Model 64

CUT-OFF

LEVEL

Model 64-CB

WARNING

CUT-OFF

LEVEL

Model 64-A

Model 764

INSTALLATION –

Model 64 – For Steam Boilers with 1” (25mm) Equalizing Lines

TOOLS NEEDED:

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

STEP 1 - Determine the Location of the 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 64 body casting should be mounted 1/2" (15mm) above the lowest visible point of the gauge glass.

STEP 2 - Installation of the Model 64

a. Locate the gauge glass and

determine the level that the 64 has to be mounted at in order to achieve the criteria in Step 1.

b. Pipe the 64 following the

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

Gauge Glass Mounted

Directly into Boiler

1" STEAM

EQUALIZING PIPE

For Boilers with

Independent Water Columns

1" WATER

EQUALIZING PIPE

c. Crosses should be used at

each right angle connection for inspection and cleaning.

d. Make sure the blow-down

CUT-OFF LEVEL

MODEL 64 LOW WATER CUT-OFF

CUT-OFF LEVEL

MODEL 64 LOW WATER CUT-OFF

valves are full port.

1" WATER

EQUALIZING PIPE

1" BLOW DOWN

VALVE

1" WATER

EQUALIZING PIPE

Test the Model 64 Before Leaving the Site

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.

IMPORTANT: Instruct boiler attendant to blow down the float chamber at least once a week during the heating

season, if operating pressure is below 15 psi (1 kg/cm

). If above 15 psi blow down once a day.

NOTE: On new boiler installations, leaky systems, or where the quality of the water is poor, blow down the control more frequently.

CAUTION

Protect yourself when blowing down controls, hot water and steam will flow out of the drain pipe attached to the blow-down valve.Failure to follow this caution may result in serious burns.

INSTALLATION –

VERTICAL RISER TO RADIAT ION

HOT WATER

BOILER

MODEL

Model 64 – For Hot Water Boilers with 1" (25mm) Equalizing Lines

TOOLS NEEDED:

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

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

a. The line on the casting of the model 64 must be installed above the lowest permissible water level

determined by the boiler manufacturer.

STEP 2 - Installation of the Model 64

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 64 control, and conform to the ASME CSD-1 code.

a. Study the figures to the right and determine which

figure shows how the 64 control will be attached to the boiler.

Figure 1. Connect the upper equalizing pipe to

VERTICAL RISER TO RADIATION OR COMPRESSION TANK

TC-4

AVAILABLE OPENING IN TOP BOILER

AIR VENT

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

HOT WATER BOILER

MODEL

HOT WATER BOILER

MODEL

no opening is available in the side of the boiler, connect the lower equalizing pipe into the drain connection.

TC-4

Figure 2. If there is a tapping available on the top of the boiler connect the upper equalizing pipe to

Figure 1

Figure 2

it. NOTE: During initial filling or after blow down the upper equalizing pipe and possibly the 64 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

compression tank. IMPORTANT: The horizontal

the equalizing run going to the radiation. If it is, an air pocket will be

pipe should not be above the horizontal

Figure 3

created and a vent or bleed will have to be installed.

Test the Model 64 Before Leaving the Site

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. NOTE: If no Test-N-Checks (TC-4) valves were used, do this test before filling the system completely.

IMPORTANT: Instruct boiler attendant to blow down the float chamber at least once a week during the heating

season, if operating pressure is below 15 psi (1 kg/cm

). If above 15 psi blow down once a day.

NOTE: On a new boiler installation, leaky system, or where the quality of the water is poor, blow down the control more frequently.

CAUTION

Protect yourself when blowing down controls, hot water will flow out of the drain pipe attached to the blow-down valve. Failure to follow this caution may result in serious burns.

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