E05
Termet
Low System Pressure / Water Pressure Fault (for hydronic furnace/boiler variants)
Furnace shows E05 and will not start, or stops shortly after starting. Often associated with low system water pressure on hydronic Termet units.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Insufficient water in system, Faulty system pressure sensor, Leaking radiator or piping, Faulty automatic fill valve
How to Fix / Troubleshooting
Safety: Turn off power. Hydronic systems can be hot and under pressure.
- Check system pressure gauge: On Termet hydronic furnaces/boilers, verify that the pressure is within the recommended range (typically 1.0–1.5 bar when cold). If low, top up via the filling loop according to the Termet manual.
- Bleed air from radiators: After topping up, bleed air from the highest radiators and recheck pressure.
- Inspect for leaks: Look for visible water around the furnace, radiators, and piping. Repair leaks before refilling repeatedly.
- Check pressure sensor connection: Locate the water pressure sensor on the hydraulic block. Ensure its connector is firmly seated and free of corrosion.
Call a technician if: Pressure drops repeatedly or the E05 persists despite correct pressure. The pressure sensor or expansion vessel may need replacement.
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Repair Difficulty
Medium
3/5
Required Part
Water Pressure Sensor
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