Install Instructions

ManualsBrandsMcdonnell & Miller ManualsHeating Supplies2, Cutoff switch for 47-2, 51-2, 51S2, 63, and 247-2

No. 2 Switch

• 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 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.

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

WARNING

OPERATION

Electrical Ratings

Motor Switch Rating (Amperes)

Voltage Full Load Locked Rotor Pilot Duty

120 VAC 10.2 61.2

125 VA at

240 VAC 5.1 30.6

120 or 240 VAC

No. 2 Switch

Applications:

For series 47, 247, 63, 51, and 53 water

feeders to add the low water cut-off

function.

McDonnell & Miller

Installation & Maintenance

Instructions

MM-704(A)

Summary of content (4 pages)

PAGE 1
McDonnell & Miller No. 2 Switch Installation & Maintenance Instructions MM-704(A) ® Applications: For series 47, 247, 63, 51, and 53 water feeders to add the low water cut-off function. No. 2 Switch OPERATION Electrical Ratings Voltage 120 VAC 240 VAC Motor Switch Rating (Amperes) Full Load Locked Rotor 10.2 61.2 5.1 30.6 Pilot Duty 125 VA at 120 or 240 VAC ! WARNING CAUT WARN ION ING • Before using this product read and understand instructions. • Save these instructions for future reference.
PAGE 2
The No. 2 Switch will help to maintain a minimum water level in the boiler during normal operation. The switch will shut off the burner in the event the boiler water level falls. Once the water level is restored to its normal level, the switch will allow the burner to operate. SCHEMATIC OF SWITCH OPERATION Low Water Alarm Terminals C. N. O. N.C. Low Water Cut-Off Terminals C. C. N.O. N.C. N.O. N.C.
PAGE 3
STEP 2 - Electrical Wiring a. Using the flathead screwdriver, remove the two (2) screws that secure the switch housing (E). b. Using copper wire only, follow the wiring diagrams in Figure 1 to wire the No. 2 Switch. Terminals C and NC are the low water cut-off switch. Terminals C and NO are the alarm switch. If the electrical load exceeds the rating of the switch, use an auxiliary relay or motor starter. E FIGURE 1 Used as a Mainline Switch and/or Low Water Alarm Neutral 120 V.A.C.
PAGE 4
McDonnell & Miller STEP 4 - Switch Adjustment The control and switch have been factory adjusted and should not need any further adjustment in the field. Observe the devices being activated by the control and switch and, should adjustment be needed, follow the following steps. a. Using a flat head screwdriver and 5/16” nut driver, loosen adjusting screw (M) until cam is set in lowest position. b.