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Heat & Glo · Gas fireplace troubleshooting

HSI fireplace: hot surface ignitor will not glow

What is going on

Heat-N-Glo hot surface ignition fireplace: the ignitor does not heat up. It will not glow without 24 VAC on the 24 V side of the module.

Likely causes

  • No 110/120 VAC at REM or at transformer terminals 1 and 3
  • Failed transformer (no 24 VAC at terminals 4 and 5)
  • Open high-temperature limit switch
  • Glass microswitch not pressed in (units with one)
  • Failed hot surface ignitor
  • Wiring fault

Check in this order

  1. Turn the On/Off rocker ON. Confirm 110/120 VAC at REM on the junction box and at L1/L2 on the module.
  2. Transformer 110/120 VAC at terminals 1 and 3, 24 VAC at terminals 4 and 5. Primary OK but no 24 VAC = replace the transformer.
  3. Module 24 VAC between 24 V and 24 V GND. Missing = check the high-temperature limit (normally closed on HSI units; no continuity = replace it) and make sure the glass microswitch is pressed in, since it only passes current when depressed.
  4. Check for 110/120 VAC at the ignitor connectors. If voltage is there, replace the ignitor.
  5. Measure ignitor resistance 45-400 ohms is good; outside that range, replace the ignitor.

Applies to: Heat-N-Glo HSI (hot surface ignition) fireplaces, Honeywell valve

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Source: Heat-N-Glo DSI / HSI Troubleshooting Guide (Professional Development), Section 7 HSI, p.47-52. 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.