Installation & Service Manual
5
Electrical connections
Maximum Set Point Determination
The maximum set point for the control is factory set.
Water heaters are set to 190°F max., and specialty state and
local codes to 200°F.
These maximum set points are established by cutting
the OJ1 and OJ2 jumpers located on the right side of
the temperature controller. The maximum set point is
determined as shown below in TABLE-5B.
TABLE 5B
MAXIMUM SET POINT DETERMINATION
OJ1
OJ2
Max. Set Point
Cut
Connected
190°F
Connected
Cut
200°F
Cut
Cut
160°F
NOTICE
Anytime that OJ1 is the only jumper
cut, a new overlay is required under
the Set Point knob on the temperature
controller because the scale has
changed to a maximum of 190°F.
Anytime the OJ2 jumper is cut (with
or without OJ1), a new overlay is
required under the Set Point knob on
the temperature controller because
the scale has changed to a maximum
of 200 °F.
Set Point
The Set Point knob specifies the target water temperature
in degrees, Fahrenheit. After the water temperature reaches
the set point, the temperature control shuts off the burners.
Differential
The Differential specifies the number of degrees below the
set point that the control will allow the water temperature to
drop before it brings the appliance back on again.
High-Fire Offset
The temperature control operates a two-stage firing system.
The two stages are High-Fire and Low-Fire. High-Fire
operates all burners while Low-Fire operates approximately
one-half of the burners.
The High-Fire knob specifies the number of degrees below
set point that the High-Fire stage shuts down. At that point,
the appliance will continue to operate at the Low-Fire stage
until the set point is reached.
They are as follows:
1. Inlet
Water
Temperature
Sensor
2. Multi-Purpose Temperature Sensor
Inlet Water Temperature Sensor
This sensor measures the inlet water temperature coming
into the appliance.
Multi-Purpose Temperature Sensor
Depending upon how your appliance is set up, this sensor
can be used as a system sensor or a tank sensor for water
heater applications. Connect this sensor to the two blue
wires in the upper left-hand corner of the control panel.
Placement of Sensors
Tank Sensor
The tank sensor is used in water heating applications.
Place the sensor in a water storage tank to measure water
temperature. For more information on mounting the sensor,
see
Remote Mounting of Sensors
this page.
Remote Mounting of Sensors
To mount remote sensors, follow the guidelines listed on this
page. Take care to correctly wire sensors to the appliance.
Erratic temperature readings can be caused by poor wiring
practices. Twist the wires between the appliance and the
remote sensor. Turn wires at least three or four turns per
linear foot of wiring. This provides protection against some
types of electrical interferences.
1. Do not route temperature sensor wiring with building
power wiring.
2. Do not locate temperature sensor wiring next to control
contactors.
The High-Fire offset knob has settings between 0°F and
20°F. If set at 0°F, the High-Fire offset is disabled and
the appliance will operate at the High-Fire stage until the
set point is reached and the temperature control shuts the
appliance off.
No matter what the High-Fire offset knob is set to, the
appliance will light at Low Fire and operate for approximately
10 to 120 seconds before the High-Fire stage actuates.
Application
Water heater appliances are shipped with two sensors;
the inlet water temperature sensor and the multi-purpose
temperature sensor to be used as a tank sensor.
Temperature Control Sensors
This is a two-stage temperature control that controls
the burner ignition, pump, and alarm functions. This
temperature controller can measure up to three different
sensor inputs, depending upon how the appliance is set up.
36
Summary of Contents for Efficiency-Pac EW 150 -- 300
Page 47: ...47 Notes ...
