Error Code
low
Rational CM – Error E24: CombiMaster Error – Software Update Required
On your CombiMaster unit, error code E24 indicates that a software update…
Rational CM - Error H20: Open water tap
Caution / Monitor Closely
Warning: The information provided here is for educational purposes only.
Working with commercial kitchen equipment involves high voltage, gas, and high temperatures.
We strongly recommend contacting a certified service technician for any repairs.
We are not responsible for any damage or injuries resulting from DIY repair attempts.
This information is provided 'as is' without any guarantees of completeness or accuracy.
TLDR
On your CombiMaster unit, error code H20 indicates an issue with the water supply, specifically that the water tap is either closed or there's insufficient water flow. This prevents the combi oven from filling its steam generator or spray system. Verify the main water tap is fully open and check for adequate water pressure.
Technical Details
Repair Steps:
- Verify Main Water Tap is Open: The most common cause for an H20 error is a closed or partially closed main water supply tap. Ensure the physical tap valve feeding your RATIONAL CombiMaster is fully open.
- Check Incoming Water Pressure: Insufficient water pressure can also trigger this error. RATIONAL units typically require a minimum of 2.5 bar (36 PSI). Verify your building’s water pressure, especially during peak usage times.
- Inspect Water Supply Lines and External Filter: Examine all water supply lines leading to the combi oven for any kinks, blockages, or closed isolation valves. Check the external water filter (e.g., Brita filter system) and scale reduction cartridge; a clogged filter can severely restrict water flow. Replace filters if they are due or appear restricted.
- Test Inlet Solenoid Valve: The CombiMaster uses an electrically controlled inlet solenoid valve to allow water into the unit. If this valve is faulty or not receiving power, water won’t enter. Test for continuity or listen for a click when the machine calls for water.
- Examine Flow Meter or Level Sensor: Some models use a flow meter or a level sensor in the steam generator to monitor water intake. Inspect these components for any blockages, debris, or mineral buildup that could prevent accurate readings or water passage.
- Check Electrical Connections: Loose or corroded wiring connections between the inlet solenoid valve, flow meter (if present), and the main PCB (Printed Circuit Board) can cause intermittent or persistent H20 errors. Power down the unit and inspect all relevant connections.
- Evaluate Main Control PCB: If all external components and connections are confirmed to be functional, the issue may lie with a faulty main control PCB. The PCB might not be sending the correct signal to the inlet valve or misinterpreting feedback from water sensors. This usually requires professional diagnostics.
Common Questions:
Q: What does the RATIONAL CombiMaster H20 error code signify?
A: The H20 error code on your RATIONAL CombiMaster indicates a problem with the water supply to the unit, most commonly that the main water tap is closed or water pressure is insufficient.
Q: What should I check first when H20 appears on my CombiMaster?
A: First, ensure the main water supply tap to the combi oven is fully open. Then, check the water pressure and inspect external water filters for blockages.
Q: Can low water pressure cause the H20 error on a RATIONAL CombiMaster?
A: Yes, absolutely. If the incoming water pressure falls below the operational minimum (typically 2.5 bar), the CombiMaster may register the H20 error due to inadequate water flow.
When to call a technician
Consider calling a certified technician if:
- The error keeps coming back after you've tried the steps above.
- You're not comfortable doing the checks or repairs yourself.
- You notice unusual noise, smell, or behaviour.
- Equipment is under warranty and you want official service.
- You need the unit back in service quickly with minimal downtime.