Install Instructions

ManualsBrandsMcdonnell & Miller ManualsHeating Supplies767, Float Type Low Water Cut-off w/ Built-in Blow-Down Valve (Steam)

Series 67 and 767

Low Water Cut-Offs

For Steam Boilers

• 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 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

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 cutoffs should be

dismantled, inspected, cleaned, and checked for proper calibration and performance.

• To prevent serious personal injury from steam and hot water make sure there is a discharge

line from the blow down valve to a proper place of disposal.

• 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.

WARNING

CAUTION

WARNING

Series 67

Series 767

Applications:

For residential and commercial boilers of

any steaming capacity.

McDonnell & Miller

Installation & Maintenance

Instructions

MM-201(E)

Summary of content (12 pages)

PAGE 1
McDonnell & Miller Installation & Maintenance Instructions MM-201(E) Series 67 and 767 Low Water Cut-Offs For Steam Boilers ® Series 67 Applications: For residential and commercial boilers of any steaming capacity. Series 767 ! WARNING ION CAUT ING WARN • Before using this product read and understand instructions. • Save these instructions for future reference.
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OPERATION Maximum Steam Pressure: 20 psi (1.4 kg/cm2) Electrical Ratings Voltage 120 VAC 240 VAC Pump Circuit Rating (Amperes) Full Load Locked Rotor 7.2 43.2 3.6 21.6 Pilot Duty 125 VA at 120 or 240 VAC Note: 11 MV is rated at 24 VA @ 24 VAC to 120 VAC The Series 67 and Series 767 low water cut-offs are float-type boiler controls designed to interrupt current to the burner whenever the water drops to the cut-off level. a 2-1/2" (63.
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STEP 2 - Preparation a. Turn the boiler off. ON OFF b. Drain the water in the boiler to a level which is below the lower gauge glass tapping (B) of the control body (A). Allow the boiler to cool to 80˚F (27˚C) and allow the pressure to release to 0 psi (0 bar). ! A B CAUTION When using the tape sealant on the external threads of pipes or fittings, follow the manufacturers instructions. Use sparingly and do not place on the first thread. STEP 3 - Installing the New Low Water Cut-Off a.
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c. Using an adjustable wrench, install a a" (9.5mm) NPT compression fitting base (K) to the upper tapping (L) in the control (A). Tighten to 31 ft•lb (42 N•m). K L A d. Using a pipe wrench, install a 2" (13mm) nipple (M) into the upper tapping (N). Tighten to 31 ft•lb (42 N•m). e. Using a pipe wrench, install the pipe tee (P) (provided) onto the nipple (M) in the upper tapping (N). Tighten to 31 ft•lb (42 N•m). f.
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g. Position the tubing (Q) next to the compression fitting (K) and, using a pencil, mark the tubing (Q) for proper insertion into the compression fitting (K). Q K Remove the tubing (Q), and, using the tube cutter, cut the tubing to its proper length. h. Insert the tubing (Q) into the upper compression fitting (U) and tighten the fitting to 31 ft•lb (42 N•m). Q U i. Using two (2) pipe wrenches, rotate the upper tee (P) counterclockwise and the lower tee (J) clockwise. P J j.
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k. Using two (2) pipe wrenches, rotate the upper tee (P) clockwise and the lower tee (J) counterclockwise so that the end of the tube can be inserted into the lower compression fitting (K). NOTE: Make sure that the control is in a horizontal position. Using an adjustable wrench, tighten the lower compression fitting (K) to 31 ft•lb (42 N•m). P K J l. Using a pipe wrench, install a w" (19mm) NPT pipe (T) into the opening of the blow down valve (U) and tighten to 47 ft•lb (64 N•m).
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b. Install the control (A) by rotating it onto the 22" (63.5mm) nipple (X, as shown in Step a on previous page). Tighten to 109 ft•lb (148 N•m). A c. Using a pipe wrench, install a w" (19mm) NPT pipe (T) into the opening of the blow down valve (U) and tighten to 47 ft•lb (64 N•m). ! CAUTION To prevent burning or scalding, pipe blow-off discharge from blow-down valve to floor – allowing enough height for a pail under discharge pipe to collect blow down discharge.
PAGE 8
STEP 4 - Electrical Wiring Directory: 67 Low Water Cut-Off and Uni-Match Water Feeder page 8 - 9 67 Low Water Cut-Off and 101 Water Feeder page 10 - 11 For 67 Low Water Cut-Off Installed with ITT McDonnell & Miller Uni-Match Water-Feeder ! 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.
PAGE 9
NOTE: To connect wires to the terminals on the water feeder, burner, or low water cut-off, place the bare end of the wire under the terminal screw and tighten the screw with a flathead screwdriver. For the 120V Burner/120V Feeder or the 24V Burner/24V Feeder setups. d. Connect a wire from the "hot" side of the power supply to the water feeder terminal #3, and low water cut-off terminal #2.
PAGE 10
For 67 Low Water Cut-Off Installed with ITT McDonnell & Miller Series 101-A Water-Feeder Y a. Using a flathead screwdriver, remove the one (1) screw that secures the low water cut-offs switch housing (Y). b. Using a flathead screwdriver, remove the two (2) screws that secure the feeder cover (BB). BB NOTE: To connect wires to the terminals on the burner, or low water cut-off, place the bare end of the wire under the terminal screw and tighten the screw with a flathead screwdriver.
PAGE 11
For the 24V Burner/24V Feeder setups. c. Connect the "hot" wire from the boiler transformer to terminal #2 of the low water cut-off. Connect the "hot" side of the water feeder transformer to terminal #3 of the low water cut-off. Connect the neutral side of the boiler transformer to the burner. Using a wire nut, connect the neutral side of the water feeder transformer to the water feeder. d. Connect the wire from the burner to terminal #1 of the low water cut-off.
PAGE 12
McDonnell & Miller For All Installations The BX outlet (GG) on the control is movable into any of the four positions by simply removing the two black-headed screws and rotating the housing. BOTTOM TOP LEFT RIGHT INSTALLATION COMPLETE MAINTENANCE SCHEDULE: • Blow down weekly (at least once) when the boiler is in operation. • Disassemble and inspect annually. Replace the low water cut-off if it is worn, corroded, or if components no longer operate properly.