Schaerer Coffee Machine Message: Hot Water or Steam Boiler Too Cold

What does Schaerer Hot water temperature too low mean?

This message on the Schaerer Coffee Soul means the hot water or the steam boiler has not reached its temperature. The table in chapter 14.4 lists three causes: the excess temperature switch has triggered, the heating phase is still running, or there was an error when heating up. The listed actions are to wait until the machine has heated up, and to disconnect it from the power supply, reconnect it and switch it on. The control compares the boiler temperature with what a drink needs, and refuses hot water or steam while the boiler is too cold. After a cold start this is normal and clears as the machine heats. The excess temperature switch is a safety cut-out that switches the heater off if the boiler gets too hot, and once it has triggered, the boiler stays cold until it is reset. The table does not give temperatures or a heat-up time, and it does not say which of the three causes applies, so a persistent message needs a technician to tell them apart.

Affected models and control systems

Schaerer Coffee Soul with the 10-inch or 12-inch display. The message is listed in the Soul operating instructions, chapter 14.4, and the manual gives no board revision or model limit for it.

Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.

What you may notice

• The display shows "Hot water temperature too low, steam boiler temperature too low"
• Hot water or steam drinks cannot be made
• The machine was just switched on or has been heating for a long time

Possible causes

Likely causes — what usually sits behind Hot water temperature too low on this control. A technician confirms which one it is before any part is replaced.

• Excess temperature switch has triggered
• Heating phase is still running
• Error when heating up
• Scale on the heating element slows heat-up or causes overheating
• A temperature sensor reads wrongly, so the heater is switched off early
• The machine is supplied with the wrong voltage or a weak phase, so the heater cannot reach temperature

Safe checks before calling for service

How a technician diagnoses Hot water temperature too low

1. Read the message and ask how long the machine has been on.
2. Check whether the excess temperature switch has tripped and why.
3. Measure heater supply and element resistance.
4. Check the boiler temperature sensor against a reference.
5. Check descaling history and the water hardness before replacing parts.

Technical reference

Document

SOUL Operating Instructions (Schaerer, Original en)

Maker documentation

Schaerer owner support

Edition

Version 04-2026 (Doc. No. Shown as '-')

Models / control

Schaerer Coffee Soul (10-inch and 12-inch display)

Section

14 Troubleshooting - 14.4 Faults with display messages: 14.4.1 Fault tables pp. 223-226, 14.4.2 Error pp. 227-228, instruction messages p. 229 (PDF pages equal printed pages)

Checked

October 2026

We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.