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Heat & Glo · Gas fireplace troubleshooting

DSI fireplace: burner lights but will not stay lit

What is going on

The burner lights and then goes out because the module does not prove flame (flame rectification).

Likely causes

  • Reversed polarity at the junction box
  • Junction box, module or burner not grounded
  • Ignitor / flame sensor not in the flame
  • Loose ignitor cable or flame sensor wire
  • Flame too close to the ceramic insulator
  • Open high-temperature limit (Fenwal units with one)
  • Grate not installed (CFX-DA)

Check in this order

  1. Warning: Disconnect 110/120 VAC before changing wiring.
  2. Check polarity meter from 120 VAC HOT on the module to ground should read 110/120 VAC; from 120 VAC RTN to ground should read 0 V. If reversed, shut off power and swap hot and neutral at the junction box.
  3. The junction box must be grounded, and the module/burner ground must be secure; ground leads must have no paint, oil or other insulation under them. The system works by flame rectification, which needs a good ground.
  4. Adjust the bracket so the probe stays in the flame whenever the burner is lit. Flame too close to the ceramic insulator causes nuisance lockouts and electrode failure.
  5. Check the ignitor cable connection. Fenwal: the yellow flame sensor wire must be on S1 at the module.
  6. CFX-DA the grate must be installed for the unit to work correctly.
  7. RAM-1-RS if polarity, grounding and probe position are all correct, replace the module.

Applies to: Heat-N-Glo DSI fireplaces: RAM 1MC1-01/-05, RAM-1-RS, Fenwal 24 VAC, CFX-DA, Grand-50-C

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Source: Heat-N-Glo DSI / HSI Troubleshooting Guide (Professional Development), p.11, 18, 24, 30, 37-38, 45. 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.