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Hot Water Systems
Shower Mixer Not Getting Hot Enough? Common Brisbane Fixes
23 March 2026 5 min read
A shower that never gets truly hot is one of the most common calls we get. Nine times out of ten it's one of these five causes.
1. Tempering Valve Set Too Low or Failing
Required by Australian Standard to limit shower water to 50°C. If it fails it can lock at 35°C — feels lukewarm.
2. Mixer Cartridge Rotation Stop
Many mixers have an adjustable stop that limits how far you can rotate to full-hot. Installers sometimes set this too conservative.
3. Cold Cross-Flow
A faulty non-return valve lets cold water push into the hot line — common in dual-inlet appliances.
4. Undersized HWS
A 125L electric can't feed a 3-head rain shower. Time for a system upgrade.
5. Failing Heating Element
Electric HWS with a partially failed element heats slowly and never reaches setpoint.
Frequently Asked Questions
Can I adjust the tempering valve myself?
No — it's a regulated safety device. A licensed plumber should test and adjust.