HVACopediaGlow Brand · Boiler
Err 105 CH supply over 180 F (82 C)
What the control is telling you
The supply sensor read above 180 F. The burner is blocked until the water cools.
Applies to: B85, B120, B160 (NG and LP)
Likely causes
- Pump not running
- Low flow through the boiler
- Supply or return sensor fault
- System pressure under 10 psi
Test and repair steps
- Check the CH, DHW and primary pumps.
- Confirm adequate flow through the boiler.
- Compare supply and return sensor readings while running.
- Make sure system pressure is above 10 psi.
Settings for these units
Maintenance intervals · Glow B85/B120/B160
| Item | When |
|---|---|
| Annual inspection by a technician | Every year (warranty) |
| Relief valve try-lever test | Annually |
| LWCO test | Annually |
| Condensate trap clean | Annually (14.3) |
| Heat exchanger combustion-side wash | Annually or when combustion drifts (14.4) |
| Burner door silicone gasket | Replace if damaged or after 2 years |
| Service reminder | 2.203 on, interval 2.204 (default 1000 days) |
Operating pressure should sit 5 psi under the relief valve rating (max 25 psig on a 30 psi valve); water never above 180 F.
Models that show this code
3 models in Glow B85/B120/B160
Other codes on the same units
- Err 101 Internal software error (blocking)
- Err 102 Internal software error (blocking)
- Err 103 Internal software error (blocking)
- Err 104 Internal software error (blocking)
- Err 106 Internal software error (blocking)
- Err 107 Internal software error (blocking)
- Err 108 Internal software error (blocking)
- Err 109 Internal software error (blocking)
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Source: Glow Brand B85/B120/B160 Installation & Operation Manual V20231025, Table 12.2 p.64. Summarized in our own words; check the original manual for your model.
Homeowner looking at this code? See what it means for you and when to call a technician.
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.