CTC Temperature Fluctuation / Short Cycling

CTC tankless water heater cycles between hot and cold water during a shower

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Flow rate below minimum, Inconsistent inlet pressure, Dirty flow sensor, Oversized unit for low-flow fixtures

Safety first: Water temperature may change suddenly; warn users before testing.

Steps to check:

Ensure the hot water flow rate meets the CTC tankless minimum (see manual); avoid using very low-flow showerheads.
Clean the flow sensor assembly and inlet filter.
Check for pressure-balancing shower valves that may be interacting poorly with the tankless heater; adjust or replace the valve.
If the unit is significantly oversized for the low-flow application, consult CTC or a plumber about flow restrictors or alternative configurations.

Medium 3/5

Flow Sensor Assembly

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