McDonnell Miller Series 42

For residential, commercial, and industrial low and medium pressure steam boiler with a separate water column.
Monel bellows provides corrosion resistance.
Single pole, single throw mercury switches.
Optional features - quick hook-up fittings, gauge glass connector, & BSPT threads.
Maximum pressure 50 psi

Replacement Heads

Model Number Part Number Description Weight lbs. Price
42-HD 129500 Replacement Head for 42 7.5 $Call

Ordering Information

Model Number Part Number Description Weight lbs. Price
42
42-A
42-J
42-N
129300
129700
129400
129800
Combination low water cut-off pump controller (Obsolete - Use 42-S)
42 w/ quick hook-up fittings
42 w/ BSPT threads
42 w/ glass connector
15.5
21.3
15.5
21.3
$519.33
$Call
$Call
$Call

Replacement Parts (View parts breakdown here)

Model Number Part Number Description Weight lbs. Price
SA150-125 348300 Switch, 2 wire (Replace with head that has the snap type switch) 0.3 $Call
SA42-125 341300 Switch, 2 wire 0.3 $Call
CO-12 302600 Head gasket (6 pack) 0.1 $19.95
MA-159 328300 Quick hook-up fittings 6.0 $353.11
SA259-24 351800* Upper quick hook-up 1.7 $88.28
SA159-24 349500* Lower quick hook-up 1.7 $91.23
SA159-17 349400* Black "Y" assembly 2.3 $65.73

Electrical Ratings

Pump Curcuit Rating
Voltage Full Load Locked Rotor Pilot duty
120 VAC

240 VAC

7.4

3.7

44.4

22.2

125 VA at 120 or 240 VAC

Alarm Circuit Rating

Voltage Amps
120 VAC

240 VAC

1

1/2

Dimensions

Model A B C D E F G
42 12 1/4 2 9/16 1 8 7/8 3 11/16 3 1/8 1/2
42-A 12 1/4 2 9/16 1 7 1/4 - 16 11/16 2 3/4 3 1/8 1/2
42-N 12 1/4 2 9/16 1 8 7/8 3 11/16 3 1/8 1/2
Model H J K L M N P Q R S T
42-N 2 9/16 2 9/16 1 3/4 3 11/16 1 13/16 1 1/16 1 1/16 1 1/2 3/8 1/4 2 5/8

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