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2150 N. RULON WHITE BLVD., OGDEN, UT 84404
Phone: 1-800-368-2493 www.chromalox.com
LOW WATER CUT-OFF — Like the pressure control, difficul-
ties can be broken down into the mechanical and electrical
groups.
The mechanical difficulties can be corrected on the high pres-
sure 100 psig motor and pump units in the following manner:
1. Remove the cover and test the free movement of the float
valve. If the float valve is in the off or down position, then the
float is either punctured or dirt and sediment is encrusted in the
float chamber. Both of these problems will involve disassem-
bly of the float chamber.
2. Check the electrical contacts to determine if they are defective.
Defective mercury tube contacts will cause the boiler to fill high-
er than normal. This occurrence will require replacement of the
mercury tube.
On low pressure feed units, the mechanical test is best made
by cleaning the valve seat beneath the float valve linkage to
assure that it is properly seated. If the valve seat is scarred or
defective, the entire valve seat must be replaced. Also, if the float
valve is in the down or “off” position, it may be punctured or
encrusted with dirt and the unit must be disassembled.
On all McDonnell-Miller cut-offs, restrictions in the equalizer
column can cause burnt out elements. The cause will appear to be
a low water condition. Regular blowdown procedures on the
equalizer column as well as the boiler will prevent this occur-
rence. Correction of the problem can be made by both removing
the plug from the side of the column and opening the Low Water
Cut-Off blowdown valves. A snake should be used to clean the
vertical and horizontal columns.
The electrical trouble shooting should be checked by referring
to the Contactors, Elements and Voltages section.
WATER FEED MECHANISMS — A common problem in this
area is boiler flooding, which may be caused by a defective float
or solenoid.
The Low Water Cut-Off must be disassembled to check the
float valve. The solenoid can be isolated by disconnecting the
union after the solenoid and energizing and de-energizing the
solenoid. If water comes out continuously or does not come out
at all, then the solenoid is defective.
A defective check valve can cause the pump motor to run
continuously or cause loss of water pressure. If the pipe between
the check valve and the water supply is hot, boiler water is back-
ing up through the check valve and the check valve must be
replaced. A defective check valve can also prevent water from
entering the boiler.
The coupling between the motor and pump may be loose; the
entire pump must be replaced if the coupling is excessively worn.
Limited Warranty:
Please refer to the Chromalox limited warranty applicable to this product at
http://www.chromalox.com/customer-service/policies/termsofsale.aspx.