Radiators heat unevenly, some are hot while others remain cool

Safety first: Use caution when bleeding radiators; water may be hot.

• 1. Bleed cool radiators: Starting with the coolest radiators, open the air vent until water flows steadily, then close. Have a container and towel ready.
• 2. Check radiator valves: Ensure supply and return valves on each radiator are fully open unless intentionally throttled for balancing.
• 3. Inspect for sludge: If certain loops never heat and bleeding does not help, there may be sludge or blockage requiring professional power flushing.
• 4. Circulator sizing: If the system has been modified or extended, a technician may need to verify that the circulator can handle the added load.