Lochinvar water heater cycles off on high limit during long hot water draws, then restarts after cooling.

Safety: High limit trips indicate overheating. Allow the unit to cool and use caution around hot piping.

Steps:

• 1. Verify flow: Check that all isolation valves on the primary loop are fully open and that the system pump is running at the correct speed.
• 2. Check for bypass: Ensure there is no unintended bypass around the heater that reduces flow through the heat exchanger.
• 3. Descale heat exchanger: If scale is suspected, have a professional perform a chemical descaling.
• 4. Upgrade pump if needed: If flow is below Lochinvar's minimum requirement, install a properly sized circulator pump.