The boiler shows A11; the unit may not respond to a thermostat or BMS call for heat.

Safety: Turn OFF power before working on low-voltage wiring.

Steps:

• 1. Verify call for heat: Check that the thermostat or building management system is actually calling for heat and is set above room temperature.
• 2. Inspect low-voltage wiring: Open the Raypak control panel and locate the thermostat or call-for-heat terminals. Ensure wires are firmly attached and not corroded or broken.
• 3. Bypass test (for diagnosis only): With power OFF, temporarily install a jumper wire across the call-for-heat terminals. Restore power. If the boiler now responds and A11 clears, the issue is in the external control or its wiring. Remove the jumper after testing.
• 4. Check control settings: Review the Raypak control menu to ensure the correct operating mode is selected (e.g., local thermostat vs. remote control). Refer to the installation manual.

If A11 persists with a confirmed call for heat and proper wiring, the control board input circuit may be defective and should be evaluated by a technician.