High Limit (Eco) Testing (Contactor Models); Mce-Vi - Bradford White MII Series Service Manual

High Limit Control (ECO) Testing for
Contactor Models
Switch Contacts:
Normally closed.
Open on rise @ 196°F ±4°F
Manual Reset.
1. Determine if Hi-Limit has actuated. This can be done by simply
depressing the reset buttons. If you hear and/or feel
a small click, the switch has actuated.
2. Use caution and turn power on to water heater and observe
heating cycle following the Hi-Limit Heating Cycle flow chart.
High Limit Control Continuity Testing for
Contactor Models
1. STOP, DANGER! Turn power "OFF" to water heater.
2. Water temperature must be below 196°F ±4°F
3. Remove Hi-Limit switch from control panel. It is not necessary
to remove immersion bulb from tank at this time. See
general controls layout on page 4 for location.
4. Disconnect wire leads to Hi-Limit Control during this test.
5. Depress reset buttons to insure switch contacts are closed.
6. Set multi-meter to Ohms setting, Check continuity Thru circuit A & B as shown in the illustrations below.
- Continuity IS present, Switch is okay.
- Continuity NOT present, Replace switch.
Circuit "A" Continuity Testing
20
Observe heating cycle.
Does switch open?
High voltage exposure. To avoid
hazard to Life or property, be sure
power is turned OFF to water heater
while performing this procedure.
NOTE
Disconnect
Wire Leads to Control
Circuit "B" Continuity Testing
Page 20
SERVICE PROCEDURE MCE-VI
High Limit (ECO) Testing
N Is water temp
over 196°F
Y
Is water temp Y
Switch OK
over 196°F
N
Replace switch
High Limit Heating Cycle Flow Chart
DANGER
Y
N