Err 129 DHW tank temperature sensor shorted

What the control is telling you

The control reads the dhw tank temperature sensor as shorted (10 kohm NTC).

Applies to: B85, B120, B160 (NG and LP)

Likely causes

• Sensor shorted
• Sensor wiring or connector
• Wrong DHW mode setting (DHW sensor only)

Test and repair steps

1. If no tank sensor is used, set DHW Mode (2.035) to 0.
2. If DHW Mode 1 is used, check the sensor wiring to terminals 5 and 6.
3. Measure the sensor it should read about 10,000 ohm at 77 F (25 C); use the resistance table for other temperatures.
4. If the resistance is right, check the wiring between sensor and control.
5. Replace the sensor.

Settings for these units

Maintenance intervals · Glow B85/B120/B160

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 122 DHW tank temperature sensor open
• Err 123 Flue temperature sensor open
• Err 126 CH return temperature sensor shorted
• Err 127 CH supply temperature sensor shorted
• Err 130 Flue temperature sensor shorted
• Err 134 Too many resets in a short time
• Err 156 Blocked flue switch open
• Err 162 Low water pressure under 10 psi (FILL)