Power Shower Not Working (Triton T90xr, Aqualisa Power Showers)
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Post a job — we'll find you an engineer →Power showers contain both high-voltage mains electrics and a pump motor. Always isolate at the consumer unit before opening the unit and confirm dead with a voltage tester. Power showers must only be installed on gravity-fed (tank-fed) systems — they are not suitable for combi boilers.
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
Understand the power shower's architecture. A power shower like the Triton T90xr is a single self-contained unit containing a cold-water inlet, a pump chamber, a heating element, and an outlet — all in one housing. It is not the same as a standard electric shower (which relies entirely on mains pressure). The pump boosts the gravity-fed supply from a header tank, so the unit must be fed from a cold-water storage cistern in the loft — not from a combi boiler or unvented cylinder (which are pressurised systems). If a power shower has been installed on a combi, it will over-pressurise the pump and fail prematurely.
No operation at all — unit does not respond: check the mains supply at the consumer unit (the Triton T90xr requires a 230 V, 30–45 A dedicated circuit). Open the unit cover (Pozidriv screws) and confirm with a voltage tester that the supply terminals are live. If power is confirmed, check the thermal cut-out (TCO) — on the T90xr, the TCO is a red reset button on the main heating element. Press it. If the TCO has tripped, also check the pump inlet filter for blockage (located at the cold inlet on the base of the unit), as a restricted flow causes the element to overheat.
Unit powers on but no water or very low water: this is usually an airlock in the pump chamber. On the Triton T90xr, airlocks occur after supply interruptions or if the cold tank runs low. To bleed the airlock: switch off the unit, connect a hose to the outlet and run it lower than the unit (below the tank feed level), then briefly switch the unit on — the pressure from the tank should push the air out through the hose. Alternatively, the pump chamber can be bled via the small bleed screw on the pump volute (if fitted — check the T90xr installation manual). Repeat two or three times if needed.
Pump runs but shower is cold — heating element fault: isolate at the consumer unit, open the cover, and use a multimeter to measure resistance across the element terminals. A healthy 9 kW element reads approximately 5.8 Ω — open circuit indicates element failure. Replacement elements for the Triton T90xr are available from Triton Showers (tritonshowers.co.uk, 024 7637 2222) — quote your model number and kW rating. Elements are a standard 41 mm thread in most units. In very hard water areas, the element can fail within 3–5 years — annual descaling significantly extends element life.
Pump is noisy but producing water: this indicates worn pump bearings or impeller damage. Power shower pumps are single-impeller units running at mains voltage — they are not the same as the separate twin-impeller gravity-fed shower pumps from manufacturers like Salamander or Stuart Turner. On the Triton T90xr, the pump is integrated into the unit and is not separately serviceable — if the pump bearings are worn, the pump motor assembly must be replaced. Triton sells refurbished pump assemblies via their spares line, and independent shower repair specialists (searchable via the Association of Plumbing and Heating Contractors, aphc.co.uk) may offer bench repair.
Shower trips the RCD or MCB when switched on: this indicates an earth fault — most commonly a failing heating element where the element insulation has broken down, creating a current path to earth. Test the element with a megohmmeter (insulation resistance tester) — resistance between the element terminals and earth should exceed 1 MΩ. Any lower and the element must be replaced. If the element tests clean but the RCD still trips, the pump motor windings may have developed an earth fault — this requires replacement of the pump motor. Always have RCD fault diagnosis confirmed by a qualified electrician before returning the shower to service.
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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.