Domakihub Fix an Electric Shower with No Hot Water
Diagnose the five most common causes before you call a licensed electrician.
Reviewed by Domakihub home & decor pros · 2026-06-23 · 5 min read
An electric shower that runs cold is one of the most frustrating problems in a Greek home, holiday rental, or hotel room — especially in shoulder season when the mains water temperature is already low. The video above walks through the five most common hardware faults in visual detail; this guide gives you the ordered diagnostic steps, clear safety boundaries, and the exact moment to stop and call a licensed electrician (ilektrologos). Understanding what is wrong before picking up the phone saves both time and money.
How electric showers work and why they stop heating
An electric shower heats cold mains water on demand as it passes over a heating element rated between 7.5 kW and 10.5 kW. Unlike a combi boiler or solar thermal system, it needs no hot-water tank — it relies entirely on mains pressure, adequate wiring, and an intact heating element. When any one of these fails, the water runs cold or lukewarm even though the unit appears to power on normally.
In Greece, electric showers are common in apartments and older houses where central heating does not supply a hot-water circuit to the bathroom. Holiday rentals and small hotels often use them as a secondary or sole heat source for a shower cubicle.
What you can safely do yourself and where to stop
A homeowner or rental manager can safely: turn off the circuit breaker, remove the unit casing to inspect visible components, test water pressure at the inlet, reset a tripped thermal cutout, and replace the showerhead or hose. None of those actions involve live mains wiring.
Any work on the fixed 10 mm cable feeding the shower, the dedicated MCB or RCD breaker, the terminal block inside the unit, or the heating element itself is mains electrical work. In Greece this must be carried out by a licensed electrician (ilektrologos with a valid GSEE/TEE permit). Attempting it yourself is both dangerous and voids the unit warranty.
Step-by-step: diagnose and fix a cold electric shower
- 1
Turn off the power at the consumer unit
Locate the dedicated MCB for the shower — typically labelled 'shower' or 'dous' and rated 40 A or 45 A on a 10 mm circuit. Switch it off and confirm the shower display or pilot light is completely dark before touching anything. If your property has a combined RCD+MCB (RCBO), flip that instead. Never rely on the pull-cord switch alone; it isolates the unit but the supply cable behind the wall remains live.
- 2
Check mains cold-water pressure at the shower inlet
Remove the shower front cover (usually two screws at the base). Locate the cold-water inlet pipe. Turn the water supply back on briefly — with the power still off — and check for a strong, steady flow. Low mains pressure is common in upper floors of Greek apartment blocks during summer peak hours and prevents the flow switch from activating the heating element, causing the unit to deliver cold water as a built-in safety measure. If pressure is weak across the whole floor, contact your plumber or the local water authority (EYDAP or DEYAB).
- 3
Reset the thermal cutout (TCO)
Electric showers include a small thermal cutout that trips when the unit overheats — often caused by a blockage or limescale build-up on the element. With the power off and the cover removed, look for a small button (usually red or white, approximately 8 to 10 mm in diameter) mounted on the element housing or on the PCB. Press it firmly until you feel a click, replace the cover, restore power, and test. If the TCO trips again within a few minutes, the underlying cause must be diagnosed by a professional. Resetting it repeatedly risks fire.
- 4
Inspect the solenoid valve and flow switch
The solenoid valve opens when you turn the shower on, allowing water into the heating chamber. The flow switch confirms water is actually moving before the element energises. Both can fail mechanically or electronically — the typical symptom is the shower appearing to activate but delivering only cold water. With the power off you can inspect the solenoid coil connector for burn marks or corrosion and check the wire harness for a loose connection. Replacing a solenoid coil is a low-voltage task that some confident DIYers attempt on certain models using the correct part number, but when in doubt hand it to an electrician or a shower repair specialist.
- 5
Call a licensed electrician if the element or wiring is suspect
If the TCO will not reset, if you find scorching around the terminal block, if the MCB trips as soon as the shower is switched on, or if the heating element tests open-circuit or short-circuit, the element or internal wiring has failed. Heating-element replacement requires disconnecting the live supply, draining the unit, and correctly re-terminating the feed cable. This is notifiable electrical work in Greece. Hire a licensed ilektrologos, ask for a receipt (apodeixi), and ensure a new Declaration of Electrical Works (Ypefthyni Dilosi) is issued for the installation. For short-term rental properties, this document is also required by the Greek tax authority (AADE).
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FAQ
- Why does my electric shower run warm for 30 seconds then turn cold?
- This usually means the heating element is partially burned out — one of the two heating stages has failed. The shower heats briefly on the remaining stage, then the thermal cutout trips. It can also point to a failing temperature selector switch. Either way, the element or internal components need professional inspection. Continuing to use the shower in this state risks a full failure or a nuisance MCB trip.
- My shower display lights up but produces only cold water — what is the most likely cause?
- The most common culprits are a tripped thermal cutout (see step 3), a failed solenoid valve that is not opening fully, or a burned-out heating element. Work through the steps in order — TCO reset first, then solenoid inspection — before concluding the element has failed. In summer in Greece, also rule out low mains pressure caused by high network demand before dismantling anything.
- Can I replace an electric shower unit myself in Greece?
- Removing and refitting the shower unit's plumbing connections (the cold-water inlet) is permissible DIY plumbing work. However, disconnecting and reconnecting the 10 mm mains supply cable at the terminal block is mains electrical work and legally requires a licensed electrician in Greece. The electrician must also update the property Ypefthyni Dilosi. For holiday-rental compliance, always keep the electrician receipt and the signed declaration on file.