Glow Brand Error Code Loc 21: Flame detected before ignition (Boiler)
Glow Brand error code Loc 21 on a boiler means: Flame detected before ignition. It is also called Glow Brand diagnostic code Loc 21.
Homeowner? What Glow Brand code Loc 21 means for you
Call a technician Your boiler is reporting: Flame detected before ignition. The boiler has locked out or cannot run properly. One reset is fine; if the code comes back, it needs a licensed technician to find the cause.
Safe things you can check yourself
- Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
- Make sure the unit has power: its on/off switch (often looks like a light switch near the unit) is ON and the breaker in the electrical panel is not tripped.
- Look at the pressure gauge on the boiler. If it reads much lower than usual or near zero, or water is leaking, call a technician.
- Outside, make sure the intake and exhaust pipes or vent cap are not blocked by snow, ice, leaves or a nest.
- Check that the boiler gas valve is open (handle in line with the pipe).
- Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.
Call (647) 657-2977Book a service call
Licensed technicians serving Vaughan, Toronto and the GTA.
What does Glow Brand error code Loc 21 mean?
A flame signal was present before the ignition sequence started.
Applies to: B85, B120, B160 (NG and LP)
Common causes of Glow Brand code Loc 21
- Ionization electrode shorted to ground
- Ignition electrode shorted to ground
- Blocked condensate drain or trap
Glow Brand models that use code Loc 21
Other Glow Brand Boiler codes
All Glow Brand Boiler error codes →
Glow Brand code Loc 21: homeowner questions
What does Glow Brand code Loc 21 mean?
Flame detected before ignition. A flame signal was present before the ignition sequence started.
Is it safe to keep using my boiler with code Loc 21?
It depends on the cause. The boiler has locked out or cannot run properly. One reset is fine; if the code comes back, it needs a licensed technician to find the cause.
Can I reset Glow Brand code Loc 21 myself?
You can try one reset (power off for 30 seconds, then on). If Glow Brand code Loc 21 comes back, the cause is still there and a licensed technician should check it.
Who can fix Glow Brand code Loc 21 near me?
Aurora Star Tech Inc. repairs Glow Brand boilers in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.
Homeowner help: Boiler Not Heating: What to Check
Troubleshooting guides
- Condensing/corrosion of conventional boiler All brands · Boiler
- No heat or some zones cold All brands · Boiler
- Noise All brands · Boiler
- Poor heat / circulation All brands · Boiler
- Relief valve weeps every cycle / pressure climbs All brands · Boiler
- Short cycling / wasted fuel All brands · Boiler
- Symptoms of air in system All brands · Boiler
- Uneven heating All brands · Boiler
- Won't fire All brands · Boiler
- Boiler pressure keeps dropping / FILL shows Glow Brand · Boiler
- Cancel the 14-minute de-air sequence Glow Brand · Boiler
- Change display units and run the display test Glow Brand · Boiler
- Cleaning the combustion side of the heat exchanger Glow Brand · Boiler
- Clear a lockout Glow Brand · Boiler
- Display is blank Glow Brand · Boiler
- Display normal but no domestic hot water (indirect tank) Glow Brand · Boiler
- Display normal but no heat to the space Glow Brand · Boiler
- Navigate the menus Glow Brand · Boiler
- Open the Installer Menu (CodE, password 0300) Glow Brand · Boiler
- Read error history and live data (Information Menu 1.000) Glow Brand · Boiler
- Reset the service reminder (wrench icon) Glow Brand · Boiler
- Run the system test (fixed fan / low / ignition / high fire) Glow Brand · Boiler
- Set the appliance type for CPVC / high temperature venting Glow Brand · Boiler
Source: Glow Brand B85/B120/B160 Installation & Operation Manual V20231025, Table 12.1 p.63. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.