McDonnell & Miller
Boiler Controls. McDonnell & Miller Low Water cut-offs are specially designed to protect steam and hot water boilers from the hazards of a low water condition. In operation they will interrupt the electrical current to the firing device, if the water in the system drops below the boiler manufacturer’s minimum safe water level. Our low water cut-offs also provide an additional circuit for a low water alarm, should you desire to install one, for additional protection.
If you have any questions please give us a call at 1-800-781-7405 or email us your request. Sales@NationalPumpSupply.com
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311200 McDonnell & Miller 21-30 Replacement Float for 21
McDonnell & Miller
$404.95311200 - McDonnell & Miller 21-30 Replacement Float for 21. Click here for more info on Mcdonnell Miller Mechanical Level & Boiler Controls For boiler receiver tanks Float operated Proportional feed action Soft seat provides positive...$404.95 -
120150 McDonnell & Miller FS7-4EL - 1-1/4" Flow Switch
McDonnell & Miller
$847.95120150 McDonnell & Miller FS7-4EL - 1-1/4" Flow Switch With NEMA 7 & 9 Enclosure w/Extended Paddle & Paddle Arm 120150. McDonnell & Miller FS7 Overview McDonnell & Miller FS7 Instruction Manual Features: For hazardous...$847.95 -
114763 McDonnell & Miller FS5-D-3/4 - 3/4" Flow Switch
McDonnell & Miller
$359.95McDonnell & Miller FS5-D-3/4 - 3/4 Flow Switch With/2 SPDT Switches 114763. McDonnell & Miller FS5 Instruction Manual Features: In-line configuration eliminates need for a pipe tee Sizes available: 3/4" NPT, 1" NPT Materials of...$359.95 -
181405 McDonnell & Miller Relief Valve 250-3/4-40
McDonnell & Miller
$184.95181405 McDonnell & Miller Relief Valve 250-3/4-40. Features and Benefits: For tanks and hydronic heating systems Protects against over-pressure Minimizes hammering with flash steam Low differential pressure – 3 psi (.21 kg/cm2) between...$184.95 -
163200 McDonnell & Miller 93 LWCO 93-7B-HB
McDonnell & Miller
$2,267.95163200 McDonnell & Miller 93 LWCO 93-7B-HB, comes with standard number 7B switch, for models #93 and #193 controls. Information: McDonnell & Miller LWCO Instruction Manual$2,267.95 -
172812 McDonnell & Miller 157S-M Hi Pressure Level Control
McDonnell & Miller
$1,421.95172812 McDonnell & Miller 157S-M Hi Pressure Level Control. McDonnell & Miller 150S/157S Instruction Manual Specifications For boilers of any steaming capacity Monel bellows provides corrosion resistance Snap action switches for high...$1,421.95 -
354001 McDonnell & Miller E-11M-24V Manual Reset Switch 24V
McDonnell & Miller
$357.95354001 McDonnell & Miller E-11M-24V Manual Reset Switch 24V. Information: McDonnell & Miller LWCO Series 67 Instruction Manual McDonnell & Miller LWCO Series 67 Submittal Sheet Features: For boilers of any steaming...$357.95 -
176802 McDonnell & Miller 157S-RD-MD Hi Pressure Level Control
McDonnell & Miller
$1,492.95176802 McDonnell & Miller 157S-RD-MD Hi Pressure Level Control. Information: McDonnell & Miller 150S/157S Instruction Manual Specifications For boilers of any steaming capacity Monel bellows provides corrosion resistance Snap action...$1,492.95 -
176503 McDonnell & Miller 157S-RBP-MD Hi Pressure Level Control
McDonnell & Miller
$2,431.95176503 McDonnell & Miller 157S-RBP-MD Hi Pressure Level Control. Information: 176503 McDonnell & Miller 150S/157S Instruction Manual Specifications For boilers of any steaming capacity Monel bellows provides corrosion resistance Snap...$2,431.95 -
176223 McDonnell & Miller 157S-P-MD Hi Pressure Level Control
McDonnell & Miller
$1,455.95176223 McDonnell & Miller 157S-P-MD Hi Pressure Level Control. McDonnell & Miller 150S/157S Instruction Manual Features For boilers of any steaming capacity Model 175802 - 157S-P Monel bellows provides corrosion resistance Snap action...$1,455.95 -
175802 McDonnell & Miller 157S-P Hi Pressure Level Control
McDonnell & Miller
$1,418.95175802 McDonnell & Miller 157S-P Hi Pressure Level Control. McDonnell & Miller 150S/157S Instruction Manual Features For boilers of any steaming capacity Model 175802 - 157S-P Monel bellows provides corrosion resistance Snap action...$1,418.95 -
172811 McDonnell & Miller Hi Pressure Level Control 157S-A-M
McDonnell & Miller
$1,628.95172811 McDonnell & Miller Hi Pressure Level Control 157S-A-M. McDonnell & Miller 150S/157S Instruction Manual Specifications For boilers of any steaming capacity Model 173702 - 157S-A-M Monel bellows provides corrosion...$1,628.95 -
172807 McDonnell & Miller Hi Pressure Level Control 150S-M-MD
McDonnell & Miller
$1,038.95172807 McDonnell & Miller Hi Pressure Level Control 150S-M-MD. McDonnell & Miller 150S Instruction Manual Specifications For boilers of any steaming capacity Monel bellows provides corrosion resistance Snap action switches for high...$1,038.95 -
137100 McDonnell & Miller 53-2 Mechanical Water Feeder
McDonnell & Miller
$1,758.95137100 McDonnell & Miller 53-2 Mechanical Water Feeder. Features: For low pressure steam and hot water boilers larger than 5,000 sq. ft. (465m2 ) with hot or cold water feed Optional features No. 2 switch Manual reset Float...$1,758.95 -
135200 McDonnell & Miller LWCO 51-2-M Mechanical Water Feeder
McDonnell & Miller
$1,558.95135200 McDonnell & Miller Mechanical Water Feeder LWCO 51-2-M. Mcdonnell & Miller 135200 Instruction Manual Features: For low pressure steam and hot water boilers larger than 5,000 sq. ft. (465m2) capacity with cold water...$1,558.95 -
153603 LWCO McDonnell & Miller PSE-801-M-U-120 Probe Control
McDonnell & Miller
$394.95The Series 153603-LWCO - McDonnell & Miller PSE-801-M-U-120 Probe Control type LWCO uses patented technology to monitor changes in water conductivity. When defined parameters are exceeded the new PSE-800 makes a decision to shut the burner off...$394.95 -
135300 McDonnell & Miller 51-2-M-HD Head Mechanism
McDonnell & Miller
$1,414.95135300 McDonnell & Miller 51-2-M-HD Head Mechanism for Mechanical Water Feeder. *Please note image is generic. This Item Usually Ships The Same Day!$1,414.95 -
165500 McDonnell & Miller LWCO 94A
McDonnell & Miller
$1,957.95165500 McDonnell & Miller High Pressure Level Control 94A. Mcdonnell & Miller Submittal Sheet Features For commercial and industrial low or high pressure steam boilers Maintains consistent water level regardless of pressure For...$1,957.95 -
132700 McDonnell & Miller Water Feeder 47
McDonnell & Miller
$1,015.95132700 McDonnell & Miller Water Feeder 47. Features: For steam and hot water boilers with cold water feed Continuous maintenance of minimum safe water level, independent of electrical service Proportional feed action Quick hook-up fittings...$1,015.95 -
114785 McDonnell & Miller FS5-J-1 Flow Switch 1 BSTB
McDonnell & Miller
$274.95114785 McDonnell & Miller FS5-J-1 Flow Switch 1 BSTB. McDonnell & Miller FS5 Instruction Manual Features: In-line configuration eliminates need for a pipe tee Sizes available: 3/4" NPT, 1" NPT Materials of construction: Brass, carbon...$274.95 -
120174 McDonnell & Miller FS7-4SDJ Flow Switch 1-1 4 BST
McDonnell & Miller
$874.95120174 McDonnell & Miller FS7-4SDJ Flow Switch 1-1 4 BST. *Please note image is generic. Mcdonnell & Miller 120160 Instruction Manual Features: Universal design serves the widest variety of large pipe applications, including heating and...$874.95 -
120171 McDonnell & Miller FS7-4SJ Flow Switch 1-1 4 BSTP
McDonnell & Miller
$958.95120171 McDonnell & Miller FS7-4SJ Flow Switch 1-1 4 BSTP. *Please note image is generic. Mcdonnell & Miller 120160 Instruction Manual Features: Universal design serves the widest variety of large pipe applications, including heating and...$958.95 -
120158 McDonnell & Miller FS7-4ELJ Flow Switch 1-1 4 BST
McDonnell & Miller
$664.95120158 McDonnell & Miller FS7-4ELJ Flow Switch 1-1 4 BST. McDonnell & Miller FS7 Overview McDonnell & Miller FS7 Instruction Manual Features: For hazardous environment applications requiring a NEMA 7 (Class I, Group C or D) or...$664.95 -
120135 McDonnell & Miller FS7-4EJ Flow Switch 1-1 4 BSTP
McDonnell & Miller
$644.95120135 McDonnell & Miller FS7-4EJ Flow Switch 1-1 4 BSTP. *Please note image is generic. McDonnell & Miller FS7 Overview McDonnell & Miller FS7 Instruction Manual Features: For hazardous environment applications requiring a NEMA 7...$644.95 -
115654 McDonnell & Miller FS6-WJ-1 Flow Switch 1 BSTP
McDonnell & Miller
$484.95115654 McDonnell & Miller FS6-WJ-1 Flow Switch 1 BSTP. *Please note image is generic. McDonnell & Miller FS6 Instruction Manual This McDonnell & Miller flow switch is for heavy duty applications where high sensitivity is required,...$484.95 -
115653 McDonnell & Miller FS6-WJ-3 4 Flow Switch 3 4 BSTP
McDonnell & Miller
$584.95115653 McDonnell & Miller FS6-WJ-3 4 Flow Switch 3 4 BSTP *Please note image is generic. McDonnell & Miller FS6 Instruction Manual This McDonnell & Miller flow switch is for heavy duty applications where high sensitivity is required,...$584.95 -
122920 McDonnell Miller AF1-J Air Flow Switch
McDonnell & Miller
$214.95122920 McDonnell Miller AF1-J Air Flow Switch. *Please note image is generic. McDonnell & Miller AF1 Flow Switch Instruction Manual For general purpose applications with medium and high velocity requirements: Paddle fits 8" (203mm) minimum...$214.95 -
120602 McDonnell & Miller FS8-WJ Flow Switch 1 BSTP
McDonnell & Miller
$284.95120602 McDonnell & Miller FS8-WJ Flow Switch 1 BSTP. *Please note image is generic. Information: Mcdonnell & Miller 120601 Instruction Manual Features: For general purpose applications with environmental exposure, or those...$284.95 -
120361 McDonnell & Miller FS7-4WLJ Flow Switch 1-1 4BSTP
McDonnell & Miller
$574.95120361 McDonnell & Miller FS7-4WLJ Flow Switch 1-1 4BSTP. *Please note image is generic. McDonnell & Miller FS7 Overview McDonnell & Miller FS7 Instruction Manual Features: Universal design serves the widest variety of large pipe...$574.95 -
119980 McDonnell & Miller FS7-4LJ Flow Switch 1-1 4 BSTP
McDonnell & Miller
$484.95119980 McDonnell & Miller FS7-4LJ Flow Switch 1-1 4 BSTP. *Please note image is generic. McDonnell & Miller FS7 Overview McDonnell & Miller FS7 Instruction Manual Features: Universal design serves the widest variety of large pipe...$484.95 -
115650 McDonnell & Miller FS6-J-1 Flow Switch 1 BSTP
McDonnell & Miller
$424.95115650 McDonnell & Miller FS6-J-1 Flow Switch 1 BSTP. *Please note image is generic. McDonnell & Miller FS6 Instruction Manual Features: In-line configuration eliminates need for a pipe tee Very high flow capacity Actuates at extremely...$424.95 -
115550 McDonnell & Miller FS6-J-3 4 Flow Switch 3 4 BSTP
McDonnell & Miller
$424.95115550 McDonnell & Miller FS6-J-3 4 Flow Switch 3 4 BSTP. *Please note image is generic. McDonnell & Miller FS6 Instruction Manual This McDonnell & Miller flow switch is for heavy duty applications where high sensitivity is required,...$424.95 -
178402 McDonnell & Miller 158S LWCO & Pump Controller
McDonnell & Miller
$1,258.95178402 McDonnell & Miller 158S LWCO & Pump Controller. McDonnell & Miller 158S Instruction Manual Features and Benefits For commercial and industrial low or high pressure Boiler applications For boilers of any steaming...$1,258.95 -
153605 McDonnell & Miller RBT-3000 LWCO & Fuel Economizer
McDonnell & Miller
$264.95153605 McDonnell & Miller RBT-3000 LWCO & Fuel Economizer. Technical Brochure The RBT-3000 is a combination Low-Water Safety Cut-Off and Fuel-Saving controller for residential heating systems. The Low Water Cut-Off is specifically designed...$264.95 -
144693 McDonnell & Miller RB-24E-S Low Water Cut Off
McDonnell & Miller
$184.95144693 McDonnell & Miller RB-24E-S Low Water Cut Off. This Item Usually Ships The Same Day!$184.95 -
178001 McDonnell & Miller 157R158S-HD Hi Pressure Level Control
McDonnell & Miller
$1,784.95178001 McDonnell & Miller 157R158S-HD Hi Pressure Level Control. Information: McDonnell & Miller 150S/157S Instruction Manual Specifications For boilers of any steaming capacity Monel bellows provides corrosion resistance Snap action...$1,784.95 -
176222 McDonnell & Miller 157S-R-MD Hi Pressure Level Control
McDonnell & Miller
$1,537.95176222 McDonnell & Miller 157S-R-MD Hi Pressure Level Control. McDonnell & Miller 150S/157S Instruction Manual Specifications For boilers of any steaming capacity Monel bellows provides corrosion resistance Snap action switches for...$1,537.95 -
172817 McDonnell & Miller 157S-M Hi Pressure Level Control
McDonnell & Miller
$1,558.95172817 McDonnell & Miller 157S-M Hi Pressure Level Control. Information: McDonnell & Miller 150S/157S Instruction Manual Specifications For boilers of any steaming capacity Monel bellows provides corrosion resistance Snap action...$1,558.95 -
176601 McDonnell & Miller 157S-RB-MD Hi Pressure Level Control
McDonnell & Miller
$1,711.95176601 McDonnell & Miller 157S-RB-MD Hi Pressure Level Control. McDonnell & Miller 150S/157S Instruction Manual Specifications For boilers of any steaming capacity Monel bellows provides corrosion resistance Snap action switches for...$1,711.95 -
172814 McDonnell & Miller 157S-RB-M Hi Pressure Level Control
McDonnell & Miller
$1,392.95172814 McDonnell & Miller 157S-RB-M Hi Pressure Level Control. Information: McDonnell & Miller 150S/157S Instruction Manual Features For boilers of any steaming capacity Model 175802 - 157S-P Monel bellows provides corrosion...$1,392.95