A.O. Smith Heat Pump Water Heater Codes: Edr, SF, ECF

By Ray Bennett · Updated 2 October 2026 · 5 min read · Checked against the maker’s manual

A.O. Smith Heat Pump Water Heater Codes: Edr, SF, ECF

Short answer

An A.O. Smith hybrid water heater shows a short code on its display, and three are normal: scrolling dashes during its start-up check, ICE during a defrost and HPO when the air is too cold or hot for the heat pump. SF means clean the air filter, Edr that the tank is not full, ECF that the compressor keeps starting and stopping, and EoF a condensate problem.

An A.O. Smith hybrid water heater, the kind with a heat pump on top of an electric tank, shows short codes on its display. Some are the heater telling you what it is doing, a few you can clear yourself, and the rest need a technician.

Everything on this page comes from A.O. Smith’s own service handbook for its residential hybrid electric heat pump water heaters, models HPTU, FHPT and SHPT. A.O. Smith says its table covers the most common codes, and to contact its technical support about any code not listed.

Before you start

What to carry: a torch, a pen and a vacuum with a hose for the filter. Ten minutes to read the code, twenty for the filter.

Gas or electric? Electric. The heat pump heats the water most of the time, and the upper and lower elements are the backup.

Give it eight minutes after power comes on. A.O. Smith says the heater runs a system check at power on, typically about eight minutes, with repeating dashes on the display.

Silence the beeping. A.O. Smith says some codes come with an audible alarm, and pressing any button on the display cancels it.

Power off before the filter or any cover. Turn the heater off at the breaker first. A.O. Smith’s handbook says to turn the power off before cleaning or replacing the air filter, and before any maintenance work.

This is a service handbook. A.O. Smith says it is for qualified service professionals, and several of its fixes need a meter and the control board. This page keeps to the checks an owner can make.

Displays that are not faults

Scrolling dashes, ICE and HPO are all listed by A.O. Smith as normal operation, no action needed.

Check 1Free, eight minutes

Rule these out first

Scrolling dashes. The start-up system check. A.O. Smith calls it normal operation.

ICE. The heat pump is in a defrost cycle. Normal.

HPO. A.O. Smith lists an air temperature below 45°F or above 120°F, and an average tank temperature of 59°F or less. The heat pump sits out until conditions change, and A.O. Smith lists it as normal operation.

Every code in A.O. Smith’s table

Code	What A.O. Smith says it means	Its corrective action
EUC	Upper element not functioning	Test and replace the element
ELC	Lower element not functioning	Test and replace the element
SF	The air filter is dirty	Clean or replace the filter
ECF	Compressor starting and stopping frequently	Fan, filter, installation space
E20, E21	Upper temperature sensor not functioning	Power cycle, connections, sensor
E30, E31	Lower temperature sensor not functioning	Power cycle, connections, sensor
E50, E51	Heat pump suction temperature sensor	Power cycle, connections, sensor
E10, E11	Heat pump coil temperature sensor	Power cycle, connections, sensor
E40, E41	Heat pump discharge temperature sensor	Power cycle, connections, sensor
E60	Upper and lower temperature sensors both not functioning	Power cycle, connections, sensor
Edr	Not enough water in the tank, the tank not full	Run the hot taps
EPL	Supply voltage too low	Loose electrical connections
EDH	Compressor discharge temperature too high	Call technical support
EoF	Condensate management	The condensate pump and drain
ECL	Heat pump suction pressure too low	The suction line sensor
EEE	Memory (EEPROM) failure	Power cycle, then the board
ECC	Heat pump compressor not functioning	The compressor checks
ECE	Power supply error	Call technical support

The checks that are yours

Four codes point first at the filter, the tank, the space around the heater and the condensate pump.

Check 2Free, twenty minutes

Work A.O. Smith's owner steps

SF, the air filter. Power off first. A.O. Smith says to vacuum the filter in place with a hose attachment, and if that does not clean it, slide it out by its two tabs and wash it with hand dishwashing soap and water, or replace it.

Edr, the tank is not full. Open all the hot water taps in the house and run them at full stream for three minutes, uninterrupted, until water flows from every one.

ECF, the compressor keeps cycling. A.O. Smith’s steps are to clean the air filter and check the heater has the room its Use and Care Guide asks for in a confined space. If the compressor runs but the fan does not, that is a technician’s flow chart.

EoF, the condensate. Check the condensate pump, if one is fitted, is plugged in and has power, including its breaker and any GFCI. Then check its outlet tube is not blocked, and that the heater stands level so the pan drains.

EPL, low voltage. A.O. Smith points at loose electrical connections, which is an electrician’s job to check.

When it needs a technician

Check 3

Know when to stop

The E sensor codes. A.O. Smith’s fix is to power cycle the heater, reseat the sensor connections on the control board, inspect the wire and replace the sensor if the code returns. That is board-level work.

EUC and ELC. An element is not working. Testing and changing one is familiar work: how to test and change a water heater element.

ECC, EDH and ECL. The compressor side. A.O. Smith sends ECC to its compressor check flow chart and EDH to technical support.

EEE and ECE. A memory failure that survives a power cycle means a new control board, and a power supply error goes to technical support.

Water on the floor. A.O. Smith’s own no hot water list includes a leak in the plumbing: where a water heater leak is really coming from.

Questions people ask

What does Edr mean on an A.O. Smith water heater?

Not enough water in the tank. Open all the hot taps in the house and run them at full stream for three minutes, uninterrupted.

What does SF mean?

The air filter is dirty. With the power off, vacuum it in place, or slide it out and wash it with dish soap and water.

What does HPO mean on an A.O. Smith hybrid?

The heat pump is off because the air is below 45°F or above 120°F, or the tank is at 59°F or less. A.O. Smith lists it as normal operation, with no action needed.

What does ICE mean?

The heat pump is defrosting its coil. It is normal and needs nothing from you.

What does ECF mean?

The compressor is starting and stopping too often. Clean the air filter and make sure the heater has the space its guide asks for.

How do I stop the beeping?

Press any button on the display. A.O. Smith says that cancels the audible alarm. It stops the sound, not the fault behind it.

Sources: A.O. Smith service handbook for residential hybrid electric heat pump water heaters, models HPTU, FHPT and SHPT