Fluidzon / Troubleshooting
Banging or Hammering Noise After Flushing
A loud banging or hammering sound occurs in the wall or pipes immediately after flushing
Identify the model first.
The same symptom can have different causes. Confirm the cistern label, installation generation and applicable manufacturer instructions. Use only safely accessible checks; ask technical support when unsure.
Help identify my cistern →Check 01
Understand Water Hammer
Water hammer is a pressure surge when the fill valve closes abruptly at the end of the fill cycle. The column of water moving through the supply pipe has nowhere to go and creates a shockwave that manifests as a loud bang inside the wall. In UAE buildings with high supply pressure and long pipe runs, this is particularly pronounced. A worn fill valve that snaps shut rather than closing gradually is the primary trigger.
Check 02
Try Reducing Supply Pressure
Partially close the isolation valve to reduce supply pressure and observe whether the banging reduces. If it does, the combination of high pressure and abrupt valve closure is causing the hammer. This is a quick test that costs nothing.
Check 03
Replace the Fill Valve
Replacing the fill valve (Part 238 956) with a new Fluidmaster unit provides a fresh diaphragm that closes progressively, dramatically reducing the pressure spike. If a mild hum persists after replacement, keep the isolation valve partially throttled.
Check 04
Check Pipe Securing
Even a small pressure surge generates a loud bang if the supply pipe is not rigidly secured. Inside the wall cavity, the supply pipe should be clipped at intervals of no more than 500 mm. Also check that the cistern frame is firmly anchored — a loose frame amplifies the sound. If reducing pressure and replacing the valve do not eliminate the banging, a pressure reducing valve (PRV) on the main supply, set to 2.5–3.0 bar, is the definitive solution. This should be installed by a qualified plumber.
These checks provide context for a support enquiry. Confirm any replacement article against the exact model drawing and manufacturer instructions.
Find the model parts catalogue →Technical support · UAE
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