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Error code reference

Bradford White Water Heater Error Code Heartbeat (alternates bright/dim)

Thermostat calling for heat (no fault)

Bradford White codesBradford White water heater codes

Thermostat calling for heat (no fault). Tank temperature below set point of thermostat.

First step from the service manual

Normal operation. Adjust thermostat to desired temperature level.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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  • Wiring diagram references and connector pinouts from the OEM service manual
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What Heartbeat (alternates bright/dim) means on a Bradford White water heater

The Heartbeat indicator on a Bradford White water heater is a normal operational status signal, not a fault code. When the pilot or status light alternates between bright and dim in a steady, rhythmic pattern, it indicates that the thermostat is actively calling for heat because the water temperature in the tank has dropped below the thermostat's set point. The control system is functioning correctly and the burner is either igniting or already running to bring the tank temperature back up to the desired level.

This signal originates from the gas control valve's integrated thermostat, which continuously monitors the stored water temperature via a sensing element. When the sensed temperature falls below the set point, the control sends a call for heat and the Heartbeat pattern begins. Once the water reaches the target temperature, the thermostat closes the call for heat and the light pattern changes to indicate a standby or satisfied condition. This cycling is a routine part of normal water heater operation and occurs multiple times per day depending on hot water usage and heat loss through the tank walls.

If the Heartbeat pattern appears to run for an unusually long time without the unit satisfying, that could indicate a separate underlying issue such as a thermostat set point that is too high for the burner to reach efficiently, excessive hot water demand, or a problem with combustion. However, on its own, the alternating bright and dim light simply confirms the heater is doing its job. No service action is required unless the heating cycle fails to complete.

Source: manufacturer service documentation.

Common causes of Heartbeat (alternates bright/dim)

  1. 01

    Normal hot water usage

    Wiring / connection

    Drawing hot water from the tank replaces it with cold inlet water, dropping the tank temperature below the set point and triggering a heating cycle. This is the most common reason for the Heartbeat pattern and requires no action.

  2. 02

    Thermostat set point recently adjusted

    Wiring / connection

    If the thermostat was recently turned up to a higher temperature, the unit will display the Heartbeat pattern continuously until the water reaches the new, higher set point. This can take 30 to 60 minutes depending on tank size.

  3. 03

    Standby heat loss after a period of inactivity

    Wiring / connection

    Even without hot water use, tanks naturally lose heat through the tank walls over time. After several hours of no use, the thermostat will call for heat to compensate for this standby loss, producing the Heartbeat pattern.

  4. 04

    Cold incoming water supply

    Wiring / connection

    During colder months, cold ground water entering the tank is significantly lower in temperature, requiring longer or more frequent heating cycles. The Heartbeat pattern will appear more often than usual but is still normal operation.

  5. 05

    Thermostat set point too high for conditions

    Wiring / connection

    If the thermostat is set near its maximum range and the Heartbeat pattern runs for extended periods without completing, verify the set point is appropriate. Extremely high settings can result in prolonged heating cycles and increased energy use.

See the test procedure for each cause

Frequently asked questions about Heartbeat (alternates bright/dim)

What does Heartbeat (alternates bright/dim) mean on a Bradford White water_heater?
The Heartbeat pattern, where the status light alternates between bright and dim, means the thermostat is calling for heat because the tank water temperature has fallen below the selected set point. This is a normal operational indicator, not a fault or error. The burner is running or preparing to run to heat the water back up to the desired temperature. No service action is needed.
Do I need to fix anything when I see the Heartbeat light on my Bradford White water heater?
No repair is needed when the Heartbeat pattern is the only indicator showing. It simply means your water heater is actively heating water, which is normal operation. If the pattern continues for an unusually long time, more than an hour or two without any hot water draw, it may be worth investigating whether the burner is completing its cycle properly.
Is it safe to use hot water while the Heartbeat light is flashing?
Yes, it is completely safe to use hot water while the Heartbeat indicator is active. The signal just means the heater is in a heating cycle. Drawing water during this time is normal and the unit will continue heating until it reaches the set temperature.
Will resetting the water heater clear the Heartbeat pattern?
Resetting the unit is not necessary and will not change anything, because the Heartbeat pattern is not a fault code. The pattern will clear on its own once the water temperature reaches the thermostat set point and the call for heat ends. If you want the unit to reach temperature faster, avoid drawing hot water until the heating cycle completes.
How much does it cost to address the Heartbeat indicator on a Bradford White water heater?
There is no cost associated with the Heartbeat indicator because it is not a fault condition. The only adjustment that may be appropriate is turning the thermostat dial to your preferred temperature setting, which requires no parts or service. If you are concerned about high energy usage from frequent heating cycles, a technician inspection typically costs between 75 and 150 dollars depending on your area.

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