How to Troubleshoot a Honeywell Aquastat

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Tip

Contact Honeywell for assistance if troubleshooting does not resolve the problem.

The Honeywell Aquastat is a controller designed for boiler water control in heating systems that are either oil or gas fired. The Aquastat uses an immersion system that has two switches controlling the high and low temperature limits on the heater. There are separate adjustments and a calibrated dial for each switch. In addition, the Aquastat has an access panel to reach all controls for the unit. If problems arise with the controller, some troubleshooting can be useful in fixing the situation.

Step 1

Reset or replace the circuit breaker or fuse if the Aquastat has completely lost power and the hot water heater is without power as well.

Step 2

Check the high limit set point if the water heater seems to turn off when the water is not very hot. The recommended set point is 140 degrees Fahrenheit. If the water temperature falls past the set point by at least 10 degrees Fahrenheit, the high limit switch resets automatically. Open the front access panel on the Aquastat and turn the "High Limit" adjustment knob to the desired set point, then replace the setting stop arm on the knob.

Step 3

Alter the low limit set point if the water heater turns off when the high limit point is set to 140 degrees and the water temperature on the water heater is below 140 degrees. The recommended low set point is 130 degrees Fahrenheit. Open the access panel and turn the "Low Limit" adjustment knob to the desired set point and replace the setting stop arm on the knob.

Step 4

Close the access panel cover.

references & resources

Meredith Jameson

Meredith Jameson writes early childhood parenting and family health articles for various online publications. She holds a Bachelor of Arts in history from San Francisco State University.