Boiler displays E19, supply/return temperature difference too high

Safety: Turn off power and let the boiler cool before bleeding or opening any piping.

• Step 1 – Check all valves: Ensure all isolation and zone valves near the Triangle Tube boiler are open for the active heating zones.
• Step 2 – Verify pump operation: Confirm the system circulator is running when there is a call for heat. If not, check its power supply and controls.
• Step 3 – Bleed air: Use air vents and bleeders to remove trapped air from high points and radiators. Refill to proper pressure.
• Step 4 – Clean strainers and filters: If present, clean any system strainers or magnetic filters to restore flow.
• Step 5 – Reset boiler: After restoring flow, reset the boiler and monitor supply and return temperatures.
• Technician tasks: If the delta-T remains high, a professional should evaluate pump sizing, inspect the heat exchanger for scaling, and adjust system hydraulics.