White Rodgers 921 User Manual

8

1

An open earth ground cir-
cuit to the ignition system

1. Check that the earth ground conductor is properly 

connected at the fuse box or breaker panel and the 
water heater.

2. Check that the grounding conductors on the water 

heater are properly connected and secure.

2

The self diagnostic test 
detected a wiring error or 
a high resistance to earth 
ground

1. Check for proper connection of the line neutral and 

line hot wires.

2. Check that the appliance is securely connected to 

earth ground.          

3

The pressure switch re-
mained closed longer that 
5 seconds after the call for 
heat began.

1. The pressure switch wiring is incorrect.
2. The pressure switch is defective and must be 

replaced.          

4

The pressure switch re-
mained open longer than 5 
seconds after the combus-
tion blower was energized

1. The pressure switch wiring is incorrect.
2. The pressure switch tubing is not connected cor-

rectly.

3. Obstructions or restrictions in the water heater air 

intake or exhaust flue.          

5

The self diagnostic test has 
detected an error in the Hot 
Surface Ignitor circuit.

1. Check that all wiring is correct and secure.
2. Disconnect the ignitor and measure the ignitor re-

sistance with an accurate ohmmeter between pins 
1 and 2. Resistance should be between 11.5 and 
18.8 ohms. If the reading is incorrect, replace the 
Hot Surface Ignitor.

3. If the above checks are good, replace the INTELLI-

VENT™ control.

6

The maximum number of 
ignition retries or recycle 
has been reached and the 
system is in lockout

1. Check if the gas supply is off or too low to operate.
2. Check that the flame sense rod to see that it is 

located properly and free from contamination. 
Reposition the flame sense rod or lightly clean with 
an abrasive cloth.

3. The Hot Surface Ignitor may not be positioned cor-

rectly. Reposition as necessary.

4. The Hot Surface Ignitor and Flame Sense Rod 

wired correctly and in good working condition. 
Repair as required.

5. Low voltage to the water heater. Check and repair.

The troubleshooting charts cover the error codes that the 
Intelli-Vent™ control can recognize, the potential cause, and 
those actions that may help repair the problem. The water 
heater manufacturer’s troubleshooting procedure should be 
consulted before attempting to repair the appliance. The wa-
ter heater manufacturer’s instructions take priority over the 
instructions here.
If for any reason you question your ability, or feel any doubt 
about your ability to perform any of the troubleshooting pro-
cedures or repairs recommended. 

and qualified service professional to repair the water 
heater.
To troubleshoot the system using the error code indicators:
1.  Check that the system is currently active and calling for a 

request for heat. You can initiate a call for heat by either 
drawing hot water from a nearby faucet or raising the tem-

perature setting (see section “Temperature Regulation”). 
If you have noted an error code from a previous heating 
cycle, this step is not necessary, and you may proceed 
with the next step.

2.  Refer to the troubleshooting charts on below to find the 

error code that is displayed. Check and repair those items 
recommended.

3.  Once the repair is complete, again initiate a call for heat, 

and observe that the ignition sequence complies with that 
shown on page 7.

4.  After the water heater repair is complete, return the water 

heater temperature setting to the original temperature. If 
for any reason you cannot remember the original setting, 
return the setting to the 120

o

F setpoint. See the section 

“Temperature Regulation” for assistance in setting the wa-
ter temperature setting.