Hydrolevel 724 Series - Manual (Page 3)

INSTALLATION & OPERATION OF FEEDER
OPERATING INSTRUCTIONS
A feed valve is supplied standard with control
model 724WF. It is recommended that a shut-off
valve and union be installed on either side of the
water feed valve and a by-pass valve and piping
be installed to permit removal of the water feed
valve should service be required. During normal
operation, by-pass valve should be closed and iso-
lation valves should remain open.
NOTE: Hydrolevel recommends that the boiler
manufacturer’s procedures for skimming the boil-
er be performed prior to placing the control into
operation. 1 1 After installation, raise the boiler water level
until water is in contact with the upper probe.
Turn on power and set the thermostat to call for
heat. The burner should fire immediately.
2 2 Using the boiler drain, slowly lower the water
level to a point below the lower probe. The
burner should shut down immediately upon a
low water condition.
NOTE: The water should not be lowered beyond
a visible point on the gauge glass.
IMPORTANT: If the burner does not shut down
in a low water condition, turn off power imme-
diately and refer to troubleshooting instructions
below.
TROUBLESHOOTING
1 1 If the burner does not shut down upon water
falling below the lower probe: Remove power to
the burner and check installation. Check wiring
and make sure that burner is connected to the
fourth terminal from left on terminal (P2). If
wiring is correct, check to make sure the
probes are not falsely grounded. Voltage
between the probes and chassis ground should be 120-140 VAC with water beneath both
probes. A lower reading may indicate a shorted
probe. Remove probes and check for contami-
nation.
2 2 If the burner will not fire with water at the top
probe: With a voltmeter and power applied at
terminals 1 and 2: Check the voltage between
the upper probe and chassis ground. Reading
should be 0-10 VAC with water at the upper
probe. A higher reading may be the result of
poorly conductive water or probe contamina-
tion. Remove probes and check for contamina-
tion. If the burner will still not fire after cleaning
probes, contact factory for assistance.
PRINCIPLE OF OPERATION
Hydrolevel controls are electronically operated.
Water is used as an electrical conductor to com-
plete a circuit from the probe to the control unit.
The control unit provides switching contacts to
operate the burner circuit and optional water feeder.
The 724 Series low water cut-off is designed to
maintain a safe operating water level in the boiler.
When water is in contact with the upper probe, the
control enables the burner to fire (switch contacts
P – P are closed). When the water level falls below
the lower probe, the control will de-energize the
burner circuit. The control will not re-energize the
burner until the water level is restored to the
upper probe level.
The 724WF includes a feed valve designed to
automatically restore the water level in the event
of a low water condition. When water falls below
the lower probe, the 724 will energize the feed
valve (switch contact 2 – V make). When the boil- er water level is restored to the upper probe, the
724 will de-energize the feed valve and restore
burner operation. The 724CF does not include a
feed valve, but does provide contacts for operation
of a steam boiler water feeder.