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Glow Brand · Boiler troubleshooting

Display normal but DHW not hot enough

Glow Combi C95 & C140

What is going on

Display normal, hot water runs, but it comes out lukewarm at the tap. Usually a setting, sometimes the mixing valve.

Likely causes

  • DHW setpoint set too low for the DHW mode
  • Faulty or misadjusted thermostatic mixing valve
  • Mixing valve set to blend in too much cold water

Check in this order

  1. Raise the DHW setpoint to the recommended value for the DHW mode (see the DHW setpoint table in this section).
  2. Check the thermostatic mixing valve for proper operation.
  3. Measure tap temperature with a thermometer after a minute of flow.
  4. Any DHW setting above 120°F requires a thermostatic mixing valve, so do not raise it without one because of scald risk.

Applies to: C95 & C140 Glow Combi boilers

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Source: C-300 C95-C140 Installation & Operation Manual, p. 74. Written in our own words; check the manual for your exact model.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.