Brochure

12
S T E A M B O I L E R C O N T R O L S
Secondary Low Water Cut-Offs – Commercial/Industrial
500 and 700 Series
•
Manual Reset with 30 Second Delay and Power
Outage Protection
•
Burner Circuit Test Button (500 Series only)
•
LED Indicating Lights
•
Meets ASME CSD-1 Requirements for Secondary
Cut-Offs on Commercial Steam Boilers
Specifications Models 500 Models 550
and 700 and 750
Power Consumption 2 VA 4 VA
Switching Capacity 50 VA 5.8 FLA, 34.8 LRA
Switch Contacts SPDT SPDT
Max. Steam Pressure 250 PSI 250 PSI
MODEL VOLTAGE DESCRIPTION/OPERATION
500 24 VAC Interrupts power in a low water condition. Burner circuit locks-out if water
550 120 VAC remains below probe for 30 seconds. Manual reset will not trip due to power
failures. Test button checks burner circuit to ensure proper control operation and
lock-out function without lowering the water level. Note: Can also be used as a
primary cut-off on hot water boilers (see page 8).
700 24 VAC Same as 500 Series above without test button feature.
750 120 VAC
Typical Steam Boiler Installations
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

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 Model 250 or 250WC
 Model 270SV High Water Limit
 Model 550 or 750 Secondary LWCO
 Model 727 Tank Pump Control