Electric shower temperature won’t adjust or is stuck at one setting (Triton & Mira)
⚠️ This needs a qualified professional
This fault involves gas or mains electrical work. Don't attempt a DIY repair — UK law requires gas work to be carried out by a Gas Safe registered engineer. Below is what to check and describe to them, not step-by-step repair instructions.
A temperature dial or control that’s stuck, won’t turn, or has no effect on actual water temperature usually points to the internal thermostatic cartridge or control mechanism rather than anything you can safely address yourself.
What’s safe to check yourself
- Check the dial or lever isn’t simply jammed by a build-up of limescale or soap residue around its housing — a gentle clean of the external control area (with the shower off) is safe and sometimes resolves a stiff dial.
- Check you’re not confusing a flow control with a temperature control — some models have separate dials for each, and it’s easy to assume the wrong one is stuck.
- Check incoming water flow (see our weak-pressure guide) — very low flow can sometimes affect how consistently an electric shower can regulate temperature, though this is different from the dial itself being physically stuck.
⚠️ This needs a qualified electrician
If the external dial genuinely turns freely but has no effect on water temperature, or is physically jammed beyond a simple external clean, the internal thermostatic cartridge or control mechanism has likely failed. This sits behind the shower’s mains electrical enclosure and must be assessed and repaired by a qualified electrician — not opened or adjusted yourself.