Power shower has stopped working
Check the steps below first — if you're not confident, get it fixed safely today.
Post a job — we'll find you an engineer →⚠️ Always isolate the electricity supply before opening any electrical shower unit. Power showers are fed from both a cold water tank and a pump — confirm the pump is off before working on it.
Power showers are brilliant when they work — they deliver a proper hot, pressurised shower from a gravity-fed system without needing a combi boiler. But when one stops working, it's frustrating because these units combine electrics, heating, and a pump all in one sealed box. The most common culprits are airlocks after a supply interruption, a tripped thermal cut-out from a blocked inlet filter, a failed heating element, or worn pump bearings. This guide walks you through the diagnosis step-by-step, from checking the electrics to bleeding the pump and testing the element. Most faults can be narrowed down in under an hour with basic tools — though if you're uncomfortable working with mains electrics or the unit is still under warranty, it's worth calling a Gas Safe registered engineer or the manufacturer's helpline rather than risking a costly mistake.
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Most likely cause & what to check
First check whether you have a power shower (pump fed from a cold water storage tank) or an electric shower (heated on demand from the mains). Power showers require a header tank in the loft and a separate pump — usually in the airing cupboard. Electric showers have a single cable and cold water supply into the unit on the wall.
Check the isolator switch — a dedicated double-pole switch outside the bathroom. Confirm it is on. Also check the consumer unit for a tripped circuit breaker on the shower or pump circuit.
In the airing cupboard, locate the shower pump (usually a grey or white box with two pipes entering and two leaving). Listen for humming — if the pump hums but produces no flow, the impeller may be air-locked. Turn the pump off and briefly open the bleed screw (if present) to release trapped air, then restart.
Check the cold water header tank in the loft — it should be at least half full. If the ball valve has stuck and the tank is empty, the pump has been running dry, which can damage the impeller seals.
If the pump runs but pressure is still poor, check the inline strainers on the pump inlet pipes — these are small mesh filters that block with debris. Unscrew and rinse them clean.
If the pump will not start at all and the electrics check out, the pump motor may have failed. A replacement pump (Stuart Turner, Grundfos, or Salamander) costs £120–£250 and is a straightforward like-for-like swap for a competent DIYer, or £300–£400 fitted by a plumber.
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Frequently asked questions
Can I fit a power shower to my combi boiler system?
No — power showers must only be installed on gravity-fed systems with a cold-water storage tank in the loft. Fitting one to a combi boiler will over-pressurise the pump and cause early failure. If you have a combi, you need a standard electric shower or a separate shower pump feeding a mixer valve instead.
My power shower has lost pressure after the water tank ran low — is it broken?
Almost certainly not — you have an airlock in the pump chamber, which is common after low-pressure events. Switch off the unit, connect a hose to the outlet, run it downhill below tank level, and briefly switch on to let the trapped air escape. You may need to repeat this two or three times before water flows normally again.
How do I know if the heating element has failed?
If the pump runs and water comes out but it's cold, the element is likely dead. You can confirm this by isolating the power at the consumer unit, opening the unit cover, and using a multimeter to test resistance across the element terminals — a working 9 kW element reads about 5.8 Ω. Open circuit means replacement is needed.
Why does my power shower trip the RCD or MCB every time I switch it on?
This indicates an earth fault, usually a failing heating element where the insulation has broken down. Test the element with an insulation resistance tester — it should read above 1 MΩ to earth. If it's lower, replace the element; if it tests clean but tripping continues, the pump motor may have developed a fault and you should call an electrician to confirm before proceeding.
How long should a power shower heating element last?
In soft water areas, 7–10 years is typical; in hard water areas, expect 3–5 years because limescale damages the element faster. Annual descaling significantly extends element life and is worth doing even if the shower is working fine — it's much cheaper than a replacement element.
My power shower pump is very noisy but still produces water — what's wrong?
The pump bearings or impeller are worn. On integrated units like the Triton T90xr, the pump cannot be serviced separately — the entire pump motor assembly must be replaced. Check with the manufacturer's spares line or contact a specialist shower repair company via the APHC for refurbished alternatives.