Whirlpool Flow Restriction / Partially Closed Valve

Whistling or high-pitched noise from the water heater when hot water is used.

Possible Causes

Partially closed shutoff valve, restricted inlet nipple, debris in the mixing valve, scale in the hot outlet.

Safety first: Use caution; pipes may be hot.

Steps:

Verify the cold water shutoff valve to the heater is fully open.
Check any installed mixing or tempering valves for restrictions; clean or replace as needed.
Inspect flex connectors for kinks or internal collapse; replace if suspected.

Easy 2/5

Cold Inlet Shutoff Valve / Mixing Valve

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