Install Instructions

ManualsBrandsMcdonnell & Miller ManualsHeating Supplies64-A-M, Float Type LWCO w/ Quick Hook Up, w/ Manual Reset

Series 64

Low Water Cut-Off

CUT-OFF

LEVEL

• 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.

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

ARNING

CAUTION

WARNING

Model 64

CUT-OFF

LEVEL

Model 64-CB

CUT-OFF

LEVEL

Model 64-A

Model 764

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/cm

)

Electrical Ratings

Motor Switch Rating (Amperes)

Voltage Full Load Locked Rotor Pilot Duty

120 VAC 7.2 43.2

120 VA at

240 VAC 3.6 21.6

120 or 240 VAC

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

McDonnell & Miller

Installation & Maintenance

Instructions

MM-200(E)

Summary of content (8 pages)

PAGE 1
McDonnell & Miller Installation & Maintenance Instructions MM-200(E) Series 64 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 CUT-OFF LEVEL Model 64 CUT-OFF LEVEL Model 64-A OPERATION Maximum Boiler Pressure: 50 psi (3.5 kg/cm2) Electrical Ratings Voltage 120 VAC 240 VAC Motor Switch Rating (Amperes) Full Load Locked Rotor Pilot Duty 7.2 43.2 120 VA at 120 or 240 VAC 3.6 21.
PAGE 2
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.
PAGE 3
INSTALLATION – 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.
PAGE 4
INSTALLATION – Model 764 – For Steam or Hot Water Boilers TOOLS NEEDED: One (1) flathead screwdriver and two (2) pipe wrenches. STEP 1 - For Steam or Hot Water Boilers where 2 1/2” (65mm) Tapping is Provided a. See figure 1. The 2 1/2” (65mm) tapping on the boiler has to be above the minimum safe operating level, as determined by the boiler manufacturer. On steam boilers, make sure the line on the casting is above the lower gauge glass nut.
PAGE 5
INSTALLATION – Model 64-A – For Steam Boilers Using Quick Hook-up Fittings TOOLS NEEDED: One (1) flathead screwdriver, two (2) pipe wrenches, and an adjustable wrench. STEP 1 - Preparing the Boiler a. Remove gauge glass and its trim from the boiler. STEP 2 - Installation of the Model 64-A a. See figures 1 and 2. Install both brass Y fittings (A) into the boiler gauge glass tappings. NOTE: If gauge glass tappings are spaced more than 10 1/8” (270mm) apart, invert the Black Y (B). See figure 2.
PAGE 6
Wiring Instructions ! WARNING • 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.
PAGE 7
Diagram 1 Diagram 2 SCHEMATIC OF TWIN SWITCH INTERNAL OPERATION 10 30 USED AS MAIN LINE SWITCH 02 04 NORMAL WATER LEVEL NEUTRAL WIRE TO BURNER HOT WIRE 10 30 02 10 30 02 04 FEEDER OR ALARM OPERATING LEVEL 10 30 SAFETY SWITCH 02 04 HOT WIRE 04 TO ALARM LOW WATER CUT-OFF OPERATING LEVEL NEUTRAL WIRE Diagram 3 Diagram 4 USED AS PILOT SWITCH IN SERIES WITH HOLDING COIL OF AUTOMATIC STARTER TO LINE USED WITH MODEL 101 ELECTRIC WATER VALVE OR IN ALARM CIRCUIT L1 L2 L3 NEUTRAL WIRE TO BURN
PAGE 8
McDonnell & Miller MAINTENANCE SCHEDULE: • Blow down weekly during heating season. • Open up float chamber and clean annually. More frequent cleaning may be necessary if there are high make-up water requirements or poor local water quality. • Replace control every 10 years. TROUBLESHOOTING 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 1 and 2 are open.