HS3 Off Due to Gas Valve alarm

What does HS3 Off Due to Gas Valve mean?

This alarm means that heating stage 3 (HS3) is deactivated due to an issue with the gas valve. It could be related to the command signal for heating or the gas valve's operational status.

• No 24 VAC power at the W3 input when heat is commanded
• The H3 output is not commanding 24 VAC to the ignition control module
• Problem with the 24 VAC for outputs terminal
• Faulty ignition control module or gas valve
• Voltage leak on the W3 terminal
• Incorrect LV phasing if two transformers are installed

Click steps to track your progress.

1. 1

   If using a 24 VAC input, check for 24 VAC at the W3 input when a heat command is active. If not using a 24 VAC input, verify the space temperature is below the heating set point.

2. 2

   Check if the H3 output is commanding 24 VAC to the ignition control module. If not, check the 24 VAC for outputs terminal.

3. 3

   If power is not present at H3 or the outputs terminal, trace the wiring for power loss. If power is present, check the ignition control module and gas valve.

4. 4

   Verify the ignition control module is completing its sequence correctly. Check for MV feedback.

5. 5

   If using a 24 VAC input to W3, ensure there is no voltage leak (even 0.5 VAC can cause issues).

6. 6

   If two transformers are installed, verify the LV phasing.