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Neither option is a universal upgrade over the other; each solves a different starting condition, and the right call is decided by the pipework already in the property, not by brand preference.
Braided and rubber flexible hoses do the same basic job, connecting a fixed pipe run to an appliance or outlet with some give in the joint, but they are built very differently underneath, and that difference shows up in how long each type lasts on a job.
Speccing the right option for a job comes down to three questions: how many outlets need hot water, how often do they run together, and what electrical supply is actually available. An instantaneous unit rated for a decent flow rate can pull a serious amount of current, and not every property has the spare capacity on the consumer unit to support it. A cylinder spreads that load differently, drawing steadily rather than in a single high spike, which is often the more practical answer on an older supply.
A mixer shower works the opposite way: it blends hot and cold water drawn from the property's existing supply, whether that is a combination boiler, a vented cylinder, or an unvented cylinder, and its performance rides entirely on what that system can provide. On a property with an unvented cylinder or a combi boiler delivering strong, consistent mains pressure to both hot and cold, a mixer shower can perform very well, often better than an electric shower, because it is not limited by the kW-versus-flow trade-off that constrains instantaneous heating. On a property with a low-pressure vented cylinder fed from a loft tank, the same mixer shower may deliver disappointing pressure unless a pump is added to the system.
For anyone new to the category, the parts worth understanding are the resin tank itself, the brine tank that holds the salt, and the control valve that manages the whole cycle, timing when regeneration happens and how much water and salt it uses. Cheaper units tend to run on a fixed timer regardless of actual usage; better-specified ones meter flow and regenerate only when the resin genuinely needs it, which uses less salt and less water over a year.
Plumb2U stocks water softeners alongside the elements, valves and fittings that hard water damage tends to bring in for replacement, at trade prices with next-day despatch, for trade buyers dealing with the practical, plumbers merchants unglamorous end of hard-water problems on a daily basis.