Triangle Tube
No Space Heating / DHW Only Operation
Display shows normal operation but radiators or space heating zones remain cold while DHW works correctly.
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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
Zone valves closed or not powered, Faulty heating circulator, Control configured for DHW only, Stuck 3-way valve on combi unit
How to Fix / Troubleshooting
Safety: Turn off power before working on circulators or zone valves.
- 1. Check thermostat calls: Ensure room thermostats are calling for heat and that their indicators (if present) show ON.
- 2. Verify zone valves: Listen and feel for zone valves opening when thermostats call. Manually open valves (if possible) to test flow.
- 3. Heating circulator: Confirm the space heating circulator pump runs during a heat call. If it hums but does not move water, it may be seized.
- 4. Control configuration: In the installer menu, verify that space heating is enabled and that priority settings are not locking out heating indefinitely.
- 5. Combi diverter valve: On combi units, ensure the diverter valve returns to the heating position after DHW calls. A stuck valve may leave the system in DHW mode.
- 6. Professional repair: Replace failed circulators or diverter valves as needed.
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Repair Difficulty
Medium
3/5
Required Part
Heating Circulator Pump
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