Nelson 700 Series Maintenance Manual Download Page 3

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not swirl out of bowl when refilling.

Note:

water seeps from top of brass shut-off valve,
tighten packing nut located below valve handle
on valve stem. Tighten no more than
necessary to stop leakage.

TESTING HEATING ELEMENT &
THERMOSTAT

Test heating element and thermostat with

ohm meter.

HEATER

Remove heater from waterer (See

Removing/Replacing Heater & Thermostat).

If the heating element is bent or warped,

replace heater. A bent or warped heater is an
indication that excessive water has been
spilled on heater when heater has been on.
Heating element will likely fail in the near
future. Excessive water spilled on the heating
element likely is an indication that there is
sediment in the valve and dripping and
overflowing is occurring. See section Dripping
& Overflow.

Test heater for continuity using an ohm

meter. Heating element should be replaced if
Ohmmeter is reading either zero or infinity.
Heating element is ok if ohmmeter display
reads 53-63 ohms on 250-watt element
(heater in model 730 waterers) and 41-48
ohms on 325-watt element (heater in model
760 waterers).

THERMOSTAT

Remove thermostat from waterer (See

Removing/Replacing Heater & Thermostat).

Place thermostat in freezer for 30

minutes. The thermostat is basically a switch.
The cold will cause the thermostat to close.

Remove from freezer and test the

thermostat for continuity using ohm meter. If
continuity is noted, thermostat is working
properly. If continuity is zero or infinity,
thermostat has failed.

REPLACING HEATER & THERMOSTAT

Use written instructions below in

conjunction with Heater & Thermostat
Installation Diagrams on page 10.

To eliminate risk of electrocution turn off

electric power supply to waterer.

Turn off water to waterer at brass shut-off

valve.

Remove the pivot beam and cage for

easy access to the junction box.

This is accomplished by first

removing the lead counter weight.

Next remove the cotter key from the

tapered end of the brass pivot shaft and
slide the brass pivot shaft out.

The pivot beam and cage may then

be removed as a unit.

Remove the cover to the junction box and

disconnect all wires in the junction box.

Take out the thermostat by removing the

mounting nut located inside the junction box
from the thermostat housing. The thermostat
is then free to be removed.

With a pair of pliers squeeze the end of the

strain relief and pull it out of the junction box

Next remove the two nuts securing the

heater assembly to the cross beam. This will

allow the heater assembly to be removed from
the waterer. The heater assembly consists of
the heating element, heat deflector, and two
sets of ceramic insulators. There are three
ceramic insulators to a set for a total of six
ceramic insulators. Also included are two
bolts, four nuts and two washers. Now when
you purchase a heater it comes as a heater
assembly.

Locate the heater assembly so that the

tip of the heating element is on the same side
as the reflector shield located at the end of the
cross beam. Snap the strain relief connector
to the end of the power cord at the base of the
stripped wires. The head of the strain relief
connector should be pointed at the heating
element.

Loop the power cord of the heater over

the cross beam along the side of the housing.
Place the stripped wires through the junction
box in the knock out hole located underneath
the thermostat. Snap the strain relief connector
into the hole. Connect the wires within the
junction box and your heater should work fine.

WEIGHT INSTALLATION

Weight Installation:

Remove shipping pads from lead weight

before installation.

Top side of weight is indicated on weight.

Moving weight in toward center lowers

water level. Moving weight out from center
increases water level.

Heater
Assembly

Ohm Meter

Thermostat

Ohm Meter

WARNING! TURN OFF
ELECTRICITY WHEN
SERVICING WATERER.