Er01 to Er19: the alarm codes on the Eliwell-based SMP55 digital thermostat, fitted to process chillers from several manufacturers.
What each code means, what causes it on site, and how to reset the flow alarm yourself.
Quick answer
On an SMP55 controller, Er01 is the flow alarm, Er02 high pressure, Er03 low refrigerant pressure, Er04 a compressor fault, Er06 a pump fault and Er09 the antifreeze alarm. Err on its own is a global alarm. The flow alarm Er01 is reset on the unit by holding the esc key for 5 seconds, once you have found and fixed the cause of the loss of flow.
What the SMP55 Is, and Where You Find It
The SMP55 is an Eliwell-based digital thermostat used as the main controller on process chillers from several manufacturers. If your display uses the Eliwell key layout, with Prg, esc, set and up and down arrows, and the parameter menus are labelled PAr and COnF, you are looking at this family.
Which controller sits behind a given chiller badge is a minefield. Manufacturers change controller between model years, between sizes in a range, and sometimes between batches, so two chillers of the same make bought two years apart can show completely different codes. That is why this library is organised by controller rather than by manufacturer.
Not sure what you have? Photograph the controller display and the data plate and send them to info@evolution-cooling.com, or call 0121 820 8946, and we will identify it and tell you what the code means. No charge.
Note that some alarms only appear if the relevant option is fitted to your machine, for example the tank level, filter and heater alarms.
Alarm Codes
| Code | Meaning | What usually causes it, and how it resets | Who can deal with it |
|---|---|---|---|
| Err | Global alarm | A general alarm indication. What has actually tripped depends on the machine, so check the alarm list on the controller. | Site team can check, engineer if unclear |
| Er01 | Flow alarm | No flow or insufficient flow through the circuit: blocked strainer, closed valve, airlocked or failing pump. The pump stops. On some configurations it clears automatically when flow returns; on others it is a manual reset, by holding the esc key for 5 seconds. Find the cause before resetting. | Site team can check the strainer, valves and pump |
| Er02 | High pressure | Dirty or blocked condenser coil, failed condenser fan, high ambient, or restricted airflow. Compressor stops. | Site team can check the coil, fans and airflow. Engineer for the rest |
| Er03 | Refrigerant low pressure | Usually refrigerant loss through a leak. Also a failing expansion device or ice on the evaporator. Resets automatically from the low pressure switch, which means a slow leak can trip and clear repeatedly before anyone notices. | F-Gas engineer needed |
| Er04 | Compressor fault | The compressor’s circuit breaker or protection has tripped. Manual reset at the breaker, and the cause needs finding first. | Engineer needed |
| Er05 | Fan fault | Condenser fan protection tripped: seized bearing, damaged blade, debris in the guard or an electrical fault. Reset is manual at the breaker, or automatic if the protection is inside the fan itself. | Engineer needed |
| Er06 | Pump fault | Pump circuit breaker tripped. Often flow set too high, a blocked cooling grille on the motor, or a failing pump. Manual reset at the breaker. | Engineer needed |
| Er07 | Water temperature probe fault | Damaged probe or cable. The machine stops. Clears automatically once the probe is replaced or repaired. | Engineer needed |
| Er08 | External temperature probe fault | As above, on the external or ambient probe where fitted. | Engineer needed |
| Er09 | Antifreeze alarm | Fluid temperature has fallen to the antifreeze setpoint. Low flow, weak or missing glycol, or a setpoint too close to freezing. Clears automatically once the temperature rises above the setpoint. Worth knowing: on a first start with ambient below 5°C this alarm can appear simply because the machine is cold. | Site team can check flow and glycol. Engineer if it repeats |
| Er10 | Antifreeze probe fault | Damaged antifreeze probe or cable. | Engineer needed |
| Er11 | Fluid minimum temperature alarm | Process fluid colder than the minimum allowed. Clears automatically once temperature rises above 5°C, or 15°C on oil-cooled versions. | Site team can check setpoint and load |
| Er12 | Fluid maximum temperature alarm | Process fluid hotter than the maximum allowed. Clears automatically below 40°C. Usually load above design, a hot fill after shutdown, or the chiller struggling. | Site team can check load, engineer if it persists |
| Er13 / Er14 | Tank minimum level alarm and pre-alarm | Water level in the tank has dropped. Er14 warns; Er13 acts. Nearly always a leak somewhere in the system, or evaporation losses never topped up. Clears when the tank is refilled, but find the leak. | Site team can refill and look for leaks |
| Er15 | Heater fault | The heater circuit breaker has tripped, on units fitted with heaters. | Engineer needed |
| Er16 | Air filter clogged | The condenser air filter needs cleaning. Clears automatically once cleaned. One of the few alarms that is genuinely a five-minute job for the site team, and one of the most preventable. | Site team can clean the filter |
| Er17 | Fluid filter clogged | The fluid or oil filter has blocked. Clears when the filter is replaced. | Site team can replace the filter |
| Er18 | Hydraulic low pressure | Water pressure in the circuit below the minimum. Usually a leak or loss of system pressure. | Site team can check pressure and top up |
| Er19 | Refrigerant pressure sensor fault | The pressure transducer is faulty or disconnected. | Engineer needed |
Not sure whether it is safe to reset? Send us a photo of the display and the data plate and we will tell you what it needs before anyone travels. Call 0121 820 8946.
How to Reset the Flow Alarm (Er01)
This is the one a site team can usually deal with, and it stops a call-out for something simple.
- The display shows Er01 and the pump has stopped.
- Find the cause first. Check the inlet strainer for debris, check isolation valves are open, check the pump is running and not airlocked, and check the system has water in it.
- Once flow can return, press and hold the esc key for 5 seconds. The alarm clears and the pump restarts.
- If Er01 comes straight back, stop. Something is still restricting flow, and repeatedly resetting will not fix it.
Viewing Alarms and Parameters
Active alarms are listed on the controller. Parameters sit behind the PAr menu, opened by pressing esc and set together, with folders including COnF for configuration.
Installation-level parameters are password protected, and changing them alters how the machine runs, including safety thresholds. That is engineer territory: a setpoint changed to “stop the alarm” is a common cause of frozen evaporators and failed compressors.
After any configuration change, the unit should be switched off and on again, or timings and configuration can misbehave.
Which SMP55 Alarms Are Safe to Reset?
- Site team can usually handle: Er01 flow after checking the cause, Er16 and Er17 filters, Er13 and Er14 tank level after refilling and checking for leaks, Er18 system pressure.
- Reset once, then stop: Er02 high pressure, Er09 antifreeze.
- Do not simply reset: Er04 compressor, Er05 fan and Er06 pump faults. These are circuit breakers that have tripped for a reason.
- Not a reset job: Er03 low refrigerant pressure, and any probe or sensor fault.
Behaviour varies with the options fitted and how the machine builder configured it, so treat this as a guide alongside the manual for your unit.
Chiller in Alarm?
Send us a photo of the controller display and the data plate. Our engineers work on process chillers from all major manufacturers, with a 4-hour response target across the West and East Midlands.
