Radiators are only partially warm; the furnace runs continuously, but the home does not reach the set temperature.

Safety first: Allow system to cool slightly before bleeding radiators.

• 1. Bleed radiators: Starting with the highest radiators, bleed air until water flows steadily. Top up system pressure as needed.
• 2. Check valves: Ensure all radiator and isolation valves are open. Verify that bypass valves are correctly set.
• 3. Pump speed: Increase pump speed if adjustable and observe improvement.
• 4. System cleaning: If some radiators remain cold at the bottom, the system may need powerflushing and inhibitor added by a heating professional.