Triangle Tube No Space Heating Circulation

No heat to radiators or underfloor loops, but boiler appears to run

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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

Failed system circulator pump, Air-locked system, Closed zone valves, Mixing valve stuck closed

How to Fix / Troubleshooting

Safety: Turn off power before opening electrical boxes or pump housings. Water may be hot.

  • Step 1 – Check boiler status: Confirm the Triangle Tube boiler is firing and reaching temperature on the display.
  • Step 2 – Feel piping: Carefully touch (briefly) the supply and return pipes leaving the boiler. If supply is hot but downstream piping is cold, flow is not reaching the system.
  • Step 3 – Verify pump operation: Listen and feel the system circulator. If silent, check its power switch, fuses, or relay. Replace the pump if it is powered but not turning.
  • Step 4 – Check zone valves: Ensure motorized zone valves are opening when thermostats call for heat. Manually open for testing if possible.
  • Step 5 – Bleed air: Bleed air from high points and manifolds to restore circulation.
  • Call a technician: For persistent no-heat issues, a professional should test pumps, valves, and system design.
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Repair Difficulty

Medium 3/5

Required Part

System Circulator Pump
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