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A

D

2

INSTALLATION –

TOOLS NEEDED:

One (1) tube cutter, one (1) pencil, one (1) flathead
screwdriver, one (1) adjustable wrench and two (2)
pipe wrenches.

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.

The Series 767 is identical to Series 67 in all
respects except one. The Series 767 is equipped with

a 2-1/2" (63.5mm) pipe tap opening in the body, and
does not require the quick hook-up fittings supplied
with the Series 67. The pipe tapping allows for a
direct connection to the side of the boiler.

Electrical Ratings

Pump Circuit Rating (Amperes)

Voltage

Full Load

Locked Rotor

Pilot Duty

125 VA at

120 or 240 VAC

For Series 67 -

The elevation of the control (A)

is already determined by the location of the
gauge glass tappings (B,C) on the boiler. The
horizontal cast line (D) should be located at or
above the boiler manufacturer's minimum safe
water level (E).

For Series 767 -

The elevation of the control (A)

is already determined by the location of the 2-
1/2 (63.5mm) pipe tapping on the boiler. The
horizontal cast line (D) of the body (A) should
be located at or above the boiler manufacturer's
minimum safe water level.

STEP 1 - Determine the Elevation at Which the
Low Water Cut-Off Controller Must be Installed

C

A

E

B

D

IMPORTANT:

Follow the boiler manufacturer's

instructions along with all applicable codes and
ordinances for piping, blow down valve and water
gauge glass installation.

OPERATION

Maximum Steam Pressure:

20 psi (1.4 kg/cm

2

)

Series 67

Series 767

Note: 11 MV is rated at 24 VA @ 24 VAC to 120 VAC

120 VAC

7.4

44.4

240 VAC

3.7

22.2

Summary of Contents for McDonnell & Miller 67 Series

Page 1: ...INSTRUCTION MANUAL MM 201H Series 67 and 767 Low Water Cut Offs For Steam Boilers...

Page 2: ...C For Series 67 The elevation of the control A is already determined by the location of the gauge glass tappings B C on the boiler The horizontal cast line D should be located at or above the boiler m...

Page 3: ...ntrol and tighten a 2 13mm NPT pipe plug G provided into the tapping on the bottom of the control body A Tighten the pipe plug to 31 ft lb 42 N m A F G When using the tape sealant on the external thre...

Page 4: ...install the pipe tee P provided onto the nipple M in the upper tapping N Tighten to 31 ft lb 42 N m N M P f Using an adjustable wrench install 1 2 13mm NPT compression fitting base U into the upper te...

Page 5: ...sing a pencil mark the tubing Q for proper insertion into the compression fitting K Remove the tubing Q and using the tube cutter cut the tubing to its proper length Q K 5 i Using two 2 pipe wrenches...

Page 6: ...down valve U and tighten to 47 ft lb 64 N m A W m Hang the blow down card W enclosed as close to the control A as possible or remove the protective backing and affix the card on the boiler jacket clo...

Page 7: ...lb 148 N m d Hang a blow down card W enclosed as close to the control A as possible or remove the protective backing and affix the card on the boiler jacket close to the control To prevent burning or...

Page 8: ...peration of all of the limit and operating controls before leaving the site Failure to follow this warning could cause electrical shock an explosion and or a fire which could result in property damage...

Page 9: ......

Page 10: ...der For the 120V Burner 120V Feeder setups BURNER 120 VAC SUPPLY 1 2 3 4 N H 101A 69 c Using a wire nut connect a wire from the neutral side of the power supply to one of the wires inside the feeders...

Page 11: ...nal 1 of the low water cut off Connect a wire from terminal 4 of the low water cut off to the remaining wire in the water feeder Wire nut together BURNER 101A 120 VAC SUPPLY N H 24V 1 2 3 4 69 Wiring...

Page 12: ...ment chemicals PROCEDURE 1 Blow down the low water cut off when the water level is at its normal level and the burner is on Fully open the blow down valve and observe the water level fall in the gauge...

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