Boiler display shows H1 and the unit runs at reduced capacity.

Safety first: Use caution around hot piping.

Steps:

• Verify setpoint: Check the Peerless control setpoint and reset curve. Reduce the maximum supply temperature if set excessively high.
• Check valves: Ensure all zone valves and isolation valves are open.
• Confirm pump sizing: Ensure the circulator is appropriate for the system and operating correctly.
• Bleed air: Remove air from radiators and high points to improve flow.