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Page 28

Copper Brute B4 Volume Water Heaters

Page 29

The flow switch is a safety device that senses 

water flow through the heater. When the switch senses 

adequate water flow, it closes, allowing the heater to 

fire. If the water flow is too low, the switch remains 

open and prevents the heater from firing regardless of 

the temperature control setting.

The flow switch is factory mounted and wired. 

Never attempt to repair the flow switch. If the flow 

switch is found to be defective, replace the flow 

switch. To test the flow switch:
1.      Remove cap from flow switch.
2.      Touch a voltmeter lead to each terminal of the 

flow switch.

3.      If the voltmeter reads voltage at each of the 

terminals, the switch is good. 

4.      If there is no voltage at one terminal, it indicates 

an open switch. Check flow switch paddles to 

determine if they are broken, missing or frozen. 

Replace the flow switch.

The fusible link is a thermally fusible element 

which shuts down the heater if it detects excessive 

temperatures inside the heater flue collector 

compartment. To test the fusible link (flame roll-out 

switch, if installed):
1.      Touch the voltmeter lead to the lower terminal on 

the terminal block (see Figure 39). 

The electrical components operate with supply 

voltage ranging from 103 to 126VAC at 60 Hertz (Hz). 

To test the electrical power supply:
1.      Measure the voltage at the hot and neutral 

connections inside the heater electrical junction 

box.

2.      Voltage outside of the required range may be due 

to poor wiring connections, to other loads (e.g., 

air conditioners, compressors) on the circuit, 

to high pump load, or to an electrical utility 

company problem.

To test the manual reset hi-limit switch (see 

Figure 38):
1.      Touch the other lead of the voltmeter to both 

terminals of the manual reset hi-limit switch. 

The voltmeter should read 24 to 28VAC at both 

terminals.

2.      If no voltage is detected at one terminal, reset the 

manual reset hi-limit switch by pressing the reset 

button. Check the temperature setting.

3.      If after pressing the reset button there is still no 

voltage indicated at one terminal, replace the 

manual reset hi-limit switch. An open switch 

may indicate excessive water temperatures or 

improper setting.

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