- Boilers
- Electric water heater
Edr
A. O. Smith Edr on a hybrid heat pump water heater: not enough water in the tank
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
On an A. O. Smith hybrid water heater, Edr means there is not enough water in the tank, which the manufacturer calls Dry Fire. Open the hot taps until water flows without interruption and check that the cold water supply is fully open.
Safety first
Stop and check this first
- Do not turn power on until the tank is full and free of air. A. O. Smith says that on a new heater a burned out element is almost always caused by powering it before it was full.
- A. O. Smith warns that this heater can make water hot enough to cause severe burns instantly; it is factory set to about 140 °F (60 °C), where a serious burn takes less than 5 seconds. It recommends thermostatic mixing valves.
Safe checks you can perform
- Filling and purging the tank
- Leaks at the connections
- Measuring the upper element
Leave these tasks to a qualified professional
- Do not attempt this professional task: Element check after an Edr
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Element check after an Edr
What they doThe technician measures the upper element with an ohmmeter and compares it with the 5 to 25 ohm range A. O. Smith gives.
They must show youthe measured value in ohms.
In writingthe value, whether the element was replaced and that the tank was filled and purged before power was restored.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Filling and purging the tank
- Who:
- you.
- How:
- fully open the heater's cold water supply valve; open all the hot taps in the home and let them run until water flows without interruption, as A. O. Smith says. In its fill procedure, water runs at full stream for three minutes.
- Result that matters:
- that every hot tap gives a steady flow, without air.
- If air or weak flow came out:
- the tank was not full; close the taps once the flow is steady and watch whether Edr clears.
- If water flowed steadily from the start and Edr remains:
- move on to the technician check.
- Evidence to keep:
- a note of how long the taps ran and whether there was a water cut.
Evidence: A. O. Smith Hybrid Electric Heat Pump Water Heater installation instructions and use and care guide
Leaks at the connections
- Who:
- you.
- How:
- dry the heater's inlet and outlet pipes with a cloth and watch them for a few minutes without touching anything electrical.
- Result that matters:
- A. O. Smith notes that almost all leaks occur at connections and are not a tank leak.
- If a connection drips:
- close the cold water valve and call the installer.
- If everything stays dry:
- the lack of water does not come from a visible leak.
- Evidence to keep:
- a photo of the connections.
Evidence: A. O. Smith Hybrid Electric Heat Pump Water Heater installation instructions and use and care guide
Measuring the upper element
- Who:
- a qualified technician.
- How:
- with power off and confirmed with a non-contact tester, disconnects the upper element wires and measures its resistance with an ohmmeter.
- Result that matters:
- A. O. Smith gives 5 to 25 ohms for a good element.
- If it reads outside that range:
- the element is damaged and is replaced.
- If it reads within range:
- the wires are reconnected tightly and the rest is checked as the manual describes.
- Evidence to keep:
- a job sheet with the measured value in ohms.
Work next to 240 V wiring. Qualified technician only, with power off and verified.
Evidence: A. O. Smith Hybrid Electric Heat Pump Water Heater installation instructions and use and care guide
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Boilers
- Brand
- A. O. Smith
- Product type
- Electric water heater
Known code variants
- A. O. Smith Edr
- A.O. Smith Edr error
- AO Smith Edr
- E dr
- EDR
- Error Edr A.O. Smith
What it means
A. O. Smith links Edr to not enough water in the tank, meaning the tank is not full, and calls it Dry Fire. The heater has dry fire protection, but the manufacturer insists that power must not be turned on until all the air is out and the tank is full. On a new heater, a burned out element is almost always caused by turning the power on before the tank was full. The code warns about the lack of water, not whether the element is already damaged.
Warnings and stop conditions
- Highsource verified
Do not turn power on until the tank is full and free of air. A. O. Smith says that on a new heater a burned out element is almost always caused by powering it before it was full.
Evidence: A. O. Smith Hybrid Electric Heat Pump Water Heater installation instructions and use and care guide
- Highsource verified
A. O. Smith warns that this heater can make water hot enough to cause severe burns instantly; it is factory set to about 140 °F (60 °C), where a serious burn takes less than 5 seconds. It recommends thermostatic mixing valves.
Evidence: A. O. Smith Hybrid Electric Heat Pump Water Heater installation instructions and use and care guide
Symptoms and causes
Probable causes · in order
- Tank not filled or holding airCommon
This is the cause A. O. Smith gives. It usually happens after installation, a drain-down or a water cut.
Evidence: A. O. Smith Hybrid Electric Heat Pump Water Heater installation instructions and use and care guide
- Cold water valve closed or partly openPossible
A. O. Smith asks for the cold water supply valve to be fully opened to fill the tank. It shows when you check the flow at the taps.
Evidence: A. O. Smith Hybrid Electric Heat Pump Water Heater installation instructions and use and care guide
Virtual technician
Does Edr still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
A. O. Smith Hybrid Electric Heat Pump Water Heater installation instructions and use and care guide
A. O. Smith · 2015 · manual
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