On the covered American electric water heater, Green LED , 1 flash means american's service table, as Sears PartsDirect publishes it, lists this code as: power applied before tank is filled with water. Open a hot tap and see whether water comes out freely and without air bursts.
Differential
Likely causes of “American electric water heater code Green LED , 1 flash”, and how to tell them apart
- 1
The heater was switched on before the tank had filled
What separates it One green flash repeats right after an installation, a replacement or a tank drain
How to confirm Open a hot tap and see whether water comes out freely and without air bursts
- 2
Air is still trapped inside the tank
What separates it The hot tap sputters and spits for a long time instead of running smoothly
How to confirm Leave the tap open until the stream is steady for a full minute
- 3
The tank was drained for maintenance and power came back before it was refilled
What separates it Someone flushed sediment or changed an element recently
How to confirm Confirm the tank is full before the breaker goes back on
- 4
The cold-water supply valve to the heater is shut
What separates it No pressure at any hot tap, or only a trickle
How to confirm Look at the valve on the cold inlet pipe above the heater and open it fully
- 5
The control has not registered that the tank is now full
What separates it The tank is full but the single flash carries on
How to confirm Switch the power off at the breaker, wait, and switch it on again
Before you touch a setting
Record this first — changing settings destroys the evidence
- That the LED is green and gives a single flash, not two or three
- Whether the tank was drained, replaced or newly installed in the last day or two
- Whether hot water runs freely at the nearest tap
- The heater's model and serial number from its label
Try in this order
0 of 7 completedCorrect only the documented fault domain
ReversibleOpen the nearest hot water faucet, and fill the water heater until a steady stream of water flows out of the faucet. Once the water heater is completely filled, then shut off the faucet. Reset the heater. Turn the power off, then back on. Press the reset button on the control box. Wait 10 minutes.
Switch the power off at the breaker
ReversibleUse the breaker that feeds the heater, not only the heater's own control, so that nothing can energise the elements while you work on the water side.
Open the nearest hot tap
ReversibleRun it fully open and wait. Air in the tank leaves through the pipes, and the tap will sputter at first and then settle into a smooth stream.
Confirm that the tank is full
ReversibleWater should run steadily for a full minute with no more air bursts. If it stops or trickles, check the cold inlet valve above the heater.
Close the tap
ReversibleTurn the tap off once the flow is steady, so that the tank stays full and under pressure.
Restore the power and reset
ReversibleSwitch the breaker on, then press the reset button on the heater's control box if the manual says to. The LED should stop flashing as the control sees a full tank.
Wait ten minutes and check the water
ReversibleThe elements need time to heat. Warm water at a tap after ten minutes shows the heater is working; an LED that still flashes once means the control is not satisfied.
Model-specific
What is true of this model and not of its siblings
- The code on this page
- Green LED, one flash: power applied before the tank is filled with water.
- Parts involved
- The tank, the cold-water supply valve, the heating elements and the control box with its reset button.
- Safety
- An electric tank must be full before power is applied, because dry elements overheat quickly.
Stop boundary
When this stops being a self-service repair
- !Never leave an electric water heater switched on with an empty or part-empty tank, because the elements overheat and fail within minutes
- !If the single flash persists with a full tank and steady taps, call a plumber or a licensed electrician
- !Switch the power off at the breaker before any access panel is removed
Evidence ledger
Sources behind this answer
Exact questions
Common questions
What does Green LED , 1 flash mean on a American electric water heater?+
American's service table, as Sears PartsDirect publishes it, lists this code as: power applied before tank is filled with water.
Has the heater been damaged?+
Not if you catch it quickly, but an element that runs dry even for a short time can burn out, so fill the tank and watch the heating.
How long should I wait before checking the water temperature?+
About ten minutes after the power is restored, which is the guide the table gives for the heater to settle.
Do I need a plumber for this?+
Only if the flash does not clear once the tank is full and the taps run smoothly, in which case a plumber or an electrician should check the control.
Should I press the reset button on the control box?+
Yes, but only once the tank is completely full and the power is back on, as pressing it on an empty tank defeats its purpose.