Tankless Water Heater Not Getting Hot Water — Descaling & High-Temp Shutdown Reset (Tampa, FL)

Tankless Water Heater Not Getting Hot Water — Descaling & Reset Service (Tampa, FL)

This service call in Tampa, Florida was for a tankless water heater not getting hot water. After diagnostics, the unit was found in a high-temperature safety shutdown, typically caused by mineral scale restricting water flow and heat transfer inside the heat exchanger.

I began by safely resetting the tankless system and confirming the unit could operate normally. When tankless heaters overheat, it’s often due to calcium and sediment buildup creating hot spots that trigger sensors and interrupt hot water delivery.

To correct the issue, I completed a professional tankless descaling service using a circulation pump and a specialized descaling solution. This process removes internal scale, restores proper flow, and allows the heater to function efficiently again.

After flushing the system with clean water, final testing confirmed consistent hot water with no error codes. Routine descaling is critical for reliable performance, efficiency, and extending the lifespan of a tankless water heater.

Tankless water heater opened for diagnostics showing internal components and temperature display during troubleshooting, Tampa, FL, January 29, 2026

Diagnostic Check & High-Temp Shutdown Reset

This image shows the initial diagnostic stage where I inspected the tankless water heater after a high-temperature shutdown. I verified sensor readings, internal components, and confirmed the unit was safe to reset before addressing the underlying cause.

Descaling setup bucket with hoses recirculating cleaning solution through tankless water heater using a circulation pump, Tampa, FL, January 29, 2026

Descaling Solution Circulation

Here the descaling flush is actively circulating a cleaning solution through the heat exchanger. This process breaks down mineral buildup, improves water flow, and prevents repeat overheating issues common with tankless systems.

Exterior tankless water heater with service valves and hoses connected for descaling and flushing maintenance, Tampa, FL, January 29, 2026

Service Valve Connections & Final Flush

This photo captures the full tankless descaling connection at the unit using isolation valves and hoses. Proper setup allows a controlled flush and thorough rinse, helping the heater operate efficiently and deliver reliable hot water.