Utica DHW Flow Control / Minimum Flow Issue

Boiler cycles on and off when only domestic hot water is used (combi models), with temperature swings at taps

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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

Low flow rate through boiler, Partially blocked DHW filter or inlet screen, Faulty flow sensor, Oversized boiler for small draws

How to Fix / Troubleshooting

Safety first: Turn off power and water supply before removing any DHW components.

  • Increase flow: Open the hot water tap more fully to see if the boiler maintains a steady burn. Very low flows may be below the boiler's minimum.
  • Clean inlet screen: On Utica combi boilers, locate and clean the cold water inlet filter screen to ensure adequate flow.
  • Check flow sensor: Inspect the DHW flow sensor for debris or sticking (follow Utica instructions). Clean or replace if necessary.
  • Professional adjustment: If cycling persists, a technician may need to adjust DHW parameters or confirm proper sizing.
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Repair Difficulty

Medium 3/5

Required Part

DHW Flow Sensor
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