Lochinvar Zone Control / Distribution Problem

Boiler cycles on and off but some zones or radiators remain cold

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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

Stuck zone valve, airlocked loop, incorrect zone control wiring, failed circulator for specific zone

How to Fix / Troubleshooting

Safety first: Turn off power before opening zone control panels or wiring compartments.

  • Check thermostats: Confirm thermostats in cold zones are calling for heat and set above room temperature.
  • Inspect zone valves: Feel the piping on both sides of each zone valve. If one side is hot and the other is cold during a call, the valve may be stuck closed. Manually open if the valve has a lever, and replace if defective.
  • Bleed air from cold zones: Use purge valves or hose connections to flush air from loops that are not heating.
  • Verify zone circulators: For systems with multiple pumps, ensure each zone pump runs when its thermostat calls.

Professional help: Persistent distribution issues may require a hydronic technician to balance and purge the system.

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Repair Difficulty

Medium 3/5

Required Part

Zone Valve
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