Type the code on your Cala's screen to see what it means and what to do. Your Cala protects itself and retries on its own, so many codes clear without you doing anything.
When something needs attention, your Cala shows a short code on its Home screen in front of a message, like L_24_16: Floor Leak Detected.
Read a code
The first letter tells you which part of your Cala the code is about:
| Letter | About | Shown on the Home screen |
|---|---|---|
H | Heat pump | Yes |
S | Sensors | Yes |
E | Heating elements | Yes |
L | Leaks | Yes |
C | Wi-Fi | No |
O | Software updates | No |
G | Clock | No |
If there is more than one problem at once, the Home screen shows the codes followed by Multiple errors occurred. Look up each code.
What to do first
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Write down the code and the message on the Home screen.
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If the leak alarm is sounding, follow Leak and heat pump alarms now.
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Type the code in Find your code above and follow What to do.
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If the code stays or keeps coming back, contact your installer or [email protected] with the code.
Heat pump codes (H)
Most heat pump codes mean the heat pump paused to protect itself. Your Cala waits, then tries again on its own. The wait starts at 1 minute and gets longer each time the same problem comes back. For most of these codes the electric heating elements take over while the heat pump waits, so you still have hot water.
A heat pump code stays on the Home screen until the heat pump next starts normally, so it can describe something that has already passed.
| Code and message | What it means | What to do | For your Cala Pro |
|---|---|---|---|
|
The water at one of the tank's temperature sensors (upper, lower, top or the hot outlet) is hotter than the tank's maximum temperature limit. Your Cala stops heating until the water cools, then carries on by itself. | Nothing to do if the code goes away. If it stays or keeps coming back, contact your installer or [email protected]. | Check the maximum temperature knob on the unit against the customer's setpoint. Check that the named thermistor is fully seated and reads a sensible temperature. Contact Cala support if the tank really is over the limit. |
|
During its start-up checks (the first time it is powered, or after more than 24 hours without power), your Cala found that the tank may not be full of water. It does not heat until the check passes, which protects the heating elements. | Make sure the cold water shut-off valve to your water heater is open. Open a hot tap until the water runs steadily with no sputtering, then close it. If the code is still there, contact your installer or [email protected]. | Fill the tank completely and bleed the air at a hot tap. Then select RERUN on the diagnostics screen. Check that the tank thermistors are seated in their wells. |
|
Your Cala measured more electrical current than expected while the heat pump was running. It pauses heating, waits and tries again. | Wait for your Cala to try again. If the code keeps coming back, contact your installer or [email protected]. | Measure supply voltage and current at the unit. Inspect the compressor and inverter wiring. Contact Cala support before replacing parts. |
|
Not used by current Cala software. | You should not see this code. If you do, contact [email protected]. | Contact Cala support. |
|
The voltage reaching the heat pump is higher or lower than it can run on. The heat pump waits and tries again. The heating elements keep your water hot in the meantime. | This often passes on its own, for example after a power outage. If lights dim or flicker in your home, call your electric utility or an electrician. If the code keeps coming back, contact your installer or [email protected]. | Measure the supply voltage at the unit's terminal block, at rest and with the unit heating. Check the breaker and supply wiring connections. |
|
The heat pump has started 6 times in the past hour, the most your Cala allows. It waits before the next start. The heating elements still work. | Nothing to do. It clears within the hour. If you see it often, contact your installer or [email protected]. | Look for another code that is stopping the heat pump shortly after each start. |
|
Your Cala's controller and the heat pump's drive stopped talking to each other, or the heat pump stopped when it wasn't asked to. The heat pump can't run until the connection is back. The heating elements still work. | Restart your Cala once. If the code comes back, contact your installer or [email protected]. | With power off at the breaker, check that the communication and power cables between the main board and the compressor inverter are fully seated and undamaged. |
|
The heat pump's drive reported that the compressor did not start, or drew too much current. The heat pump waits and tries again. The heating elements keep your water hot in the meantime. | Wait for your Cala to try again. If the code keeps coming back, contact your installer or [email protected]. | Check supply voltage and the compressor and inverter connections. Contact Cala support before replacing parts. |
|
The electronics that drive the heat pump got too hot. The heat pump waits and tries again. The heating elements keep your water hot in the meantime. | Clean the air filter. Make sure nothing blocks the air going into or out of your Cala and that the room isn't very hot. If the code keeps coming back, contact your installer or [email protected]. | Check that the fan runs and that airflow and any ducting are clear. Check the room temperature. |
|
The pressure inside the heat pump is higher than expected. If it stays high, the heat pump waits and tries again. The heating elements keep your water hot in the meantime. | Clean the air filter and make sure nothing blocks the air going into or out of your Cala. If the code keeps coming back, contact your installer or [email protected]. | Check the fan, airflow and the pressure sensor connectors. Never open the sealed refrigerant circuit. Contact Cala support. |
|
The cold side of the heat pump got colder than it should. This is normal after a very large amount of hot water has been used and the tank is full of cold water, or when the air around your Cala is very cold. Your Cala recovers by itself, using the heating elements if it needs to. | Give the tank several hours to recover. Clean the air filter. If it happens without heavy hot water use, or the tank hasn't recovered after 12 hours, contact your installer or [email protected]. | Check the air filter, fan and airflow. Check the room temperature: the heat pump runs between 37 °F and 120 °F. A space that stays cold may need ducting or a warmer location. Check the suction sensor connectors. Never open the sealed refrigerant circuit. |
|
The heat pump is running hotter than expected. It waits and tries again. The heating elements keep your water hot in the meantime. | Clean the air filter. Make sure nothing blocks the air going into or out of your Cala and that the room isn't very hot. If the code keeps coming back, contact your installer or [email protected]. | Check the fan and airflow. Check that the discharge and suction line thermistors are attached to their pipes. Never open the sealed refrigerant circuit. Contact Cala support. |
|
The heat pump ran for an hour without warming up the way it should. It waits and tries again. The heating elements keep your water hot in the meantime. | If the code keeps coming back, contact your installer or [email protected]. | Check that the discharge line thermistor is attached to its pipe and connected. Never open the sealed refrigerant circuit. Contact Cala support. |
|
Used only when Cala tests each water heater at the factory. | You should not see these codes at home. If you do, contact [email protected]. | Contact Cala support. |
Sensor codes (S)
Your Cala checks its sensors all the time. If a reading is outside the range that makes sense for more than 5 seconds, it pauses heating until the reading is back, then carries on by itself.
Each sensor has up to three codes. The last number tells you what is wrong with the reading:
0 means Over Range (too high), 1 means
Under Range (too low) and 2 means
NaN (no reading at all).
| Code and message | What it means | What to do | For your Cala Pro |
|---|---|---|---|
|
One of the water temperature sensors (thermistors) in the tank or at the hot outlet is giving a reading that can't be right. Your Cala pauses heating until the reading returns. | Restart your Cala once. If the code stays or comes back, contact your installer or [email protected]. | With power off at the breaker, check the named thermistor's connector at the main board and its cable. Under Range usually means an open or unplugged circuit; Over Range usually means a short. Measure the thermistor and replace it if it is out of spec. |
|
One of the temperature sensors on the heat pump's pipes is giving a reading that can't be right. Your Cala pauses heating until the reading returns. | Restart your Cala once. If the code stays or comes back, contact your installer or [email protected]. | With power off at the breaker, check the named thermistor's connector and cable, and that the thermistor is attached to its pipe. Under Range usually means an open or unplugged circuit; Over Range usually means a short. |
|
The air around your Cala is hotter than 120 °F or colder than 37 °F, outside the range the heat pump runs in. The heat pump rests for 24 hours and the heating elements keep your water hot. | Nothing to do: you still have hot water. Once the room is back to a normal temperature, you can restart your Cala to bring the heat pump back sooner. If the space is often that hot or cold, talk to your installer. | Confirm the room temperature at the unit. A space that is regularly outside 37 °F to 120 °F may need ducting or a different location. |
|
The sensor that measures the air temperature and humidity around your Cala isn't giving a usable reading. Your Cala pauses heating until the reading returns. | Restart your Cala once. If the code stays or comes back, contact your installer or [email protected]. | With power off at the breaker, check the air temperature and humidity sensor's cable and connector. Replace the sensor if the fault stays. |
|
One of the pressure sensors inside the heat pump is giving a reading that can't be right. These measure the heat pump, not your home's water pressure. Your Cala pauses heating until the reading returns. | Restart your Cala once. If the code stays or comes back, contact your installer or [email protected]. | With power off at the breaker, check the pressure sensor connectors and cables. Never open the sealed refrigerant circuit. Contact Cala support. |
|
Your Cala has a second, independent safety system that watches the tank temperature and the heat pump. It has stopped all heating. It releases by itself once the cause is gone. | Contact [email protected] and tell us any other code on the screen. Don't keep switching the power off and on to clear it. If you smell burning or see scorching or water at the unit, turn off its circuit breaker. | Contact Cala support before doing any work. Never bypass or defeat the safety system. |
|
The sensor that measures how much hot water you use is giving a reading that can't be right. Your Cala pauses heating until the reading returns. | Restart your Cala once. If the code stays or comes back, contact your installer or [email protected]. | With power off at the breaker, check the flow meter's cable and connector. |
|
The supply voltage your Cala measures is far too high, far too low or unreadable. Your Cala pauses heating until the reading returns. | This can happen briefly around a power outage. If lights dim or flicker in your home, call your electric utility or an electrician. If the code stays, contact your installer or [email protected]. | Measure the supply voltage at the unit's terminal block and check the supply wiring connections. |
|
During its start-up checks, your Cala measured an electrical current that doesn't make sense with everything switched off. | If the code stays or comes back, contact your installer or [email protected]. | Check for a relay that is stuck closed and check the current sensor. Contact Cala support. |
Heating element codes (E)
Your Cala has two electric heating elements, upper and lower, that back up the heat pump. Codes
with 15 are for the upper element and codes with 16 are for the lower.
| Code and message | What it means | What to do | For your Cala Pro |
|---|---|---|---|
|
A heating element was switched on 10 times within 5 minutes. Your Cala pauses heating for 5 minutes, then carries on by itself. | Nothing to do. If you see it often, contact your installer or [email protected]. | Contact Cala support if it repeats. |
|
A heating element is drawing more electrical current than it should. Your Cala pauses heating, waits and tries again. | Contact your installer or [email protected]. | With power off at the breaker, measure the element's resistance and inspect its wiring. Check the supply voltage. Replace the element if it is out of spec, then select CLEAR LOCKOUTS. |
|
A heating element is drawing less electrical current than it should, which usually means the element or its wiring has failed. Your Cala pauses heating, waits and tries again. | Contact your installer or [email protected]. | With power off at the breaker, measure the element's resistance and check its wiring and connections. Check the supply voltage on both legs. Replace the element if it is open, then select CLEAR LOCKOUTS. |
Leak codes (L)
Leak codes come with the leak alarm. The code and the alarm clear by themselves as soon as the sensors are dry. For the full steps, see Leak and heat pump alarms.
| Code and message | What it means | What to do | For your Cala Pro |
|---|---|---|---|
|
The drip tray under the heat pump is full of water. The heat pump stays off until the tray is dry, and the heating elements keep your water hot. | Follow the steps in Leak and heat pump alarms, then check the condensate line. | Clear a condensate drain line that is clogged, kinked or frozen, and check the condensate pump if one is fitted. Re-route the line if it can't drain. |
|
The leak detector on the floor under your Cala is wet. This is an alert only: your Cala keeps heating and does not shut off the water. | Follow the steps in Leak and heat pump alarms to turn off the power and water and find the source. | Check the plumbing fittings, the temperature and pressure relief valve discharge, and the condensate drain. Contact Cala support if the water is coming from the unit itself. |
|
Both the floor leak detector and the drip tray are wet. The heat pump stays off until the tray is dry, and the heating elements keep your water hot. | Follow the steps in Leak and heat pump alarms straight away. | Check everything listed for the two codes above. Contact Cala support if the water is coming from the unit itself or the codes return with a clear drain. |
Wi-Fi codes (C)
Wi-Fi codes don't appear on the Home screen. The Wi-Fi icon there shows Not Connected instead.
| Code and message | What it means | What to do | For your Cala Pro |
|---|---|---|---|
|
Your Cala has been offline for more than a minute. It keeps heating normally. The Cala app, energy-saving features that need the internet and software updates wait until it is back online. | Reconnect your Cala to Wi-Fi. | Check the Wi-Fi signal where the unit is installed and that the router's 2.4 GHz band is on. |
|
Not used by current Cala software. | You should not see this code. If you do, contact [email protected]. | Contact Cala support. |
Software update codes (O)
Software update codes never affect your hot water and don't appear on the Home screen. If an update can't finish, your Cala keeps running the version it has and tries again later. Each code clears by itself after 30 minutes. See Firmware updates.
| Code and message | What it means | What to do | For your Cala Pro |
|---|---|---|---|
|
Your Cala couldn't reach the update service, or the download was interrupted. | Check that your Cala is online. If its Wi-Fi drops often, reconnect it to Wi-Fi. Your Cala tries the update again by itself. | Check the Wi-Fi signal where the unit is installed. |
|
The update file couldn't be read or didn't finish installing. | Nothing to do. Your Cala tries the update again by itself. | Nothing to service. |
|
Your Cala checks that every update really comes from Cala before installing it. This update didn't pass that check, so it was not installed. | Nothing to do. If your Cala stays on an old version, contact [email protected]. | Nothing to service. Contact Cala support if it repeats. |
|
A new version didn't run properly after it installed, so your Cala went back to the version it was running before. | Nothing to do. Your Cala keeps working on its earlier version and gets the next update by itself. | Nothing to service. |
|
The update on offer isn't newer than the version your Cala already has. | Nothing to do. | Nothing to service. |
Clock codes (G)
Your Cala has a built-in clock with a backup battery. Clock codes never affect your hot water and don't appear on the Home screen. They are checked when your Cala starts and clear by themselves after 30 minutes.
| Code and message | What it means | What to do | For your Cala Pro |
|---|---|---|---|
|
The built-in clock lost its time while your Cala was without power. Your Cala sets its clock again from the internet. | Keep your Cala connected to Wi-Fi. Nothing else to do. | Contact Cala support if it appears after every power loss. |
|
The built-in clock isn't working properly. Your Cala sets its clock from the internet instead. | Keep your Cala connected to Wi-Fi. If the times on your Cala look wrong, contact [email protected]. | Contact Cala support. |
Clear a lockout
If the same problem happens many times in a row, your Cala stops retrying (a lockout). Once the cause is fixed, select CLEAR LOCKOUTS on the ADVANCED screen. See Restart or factory reset your water heater for the steps.