This is an old revision of the document!
Length matters just as much, and not only for reach. A flexi hose that is too long for the gap it is bridging tends to kink or sit under unnecessary strain, both of which shorten its working life. Too short, and it is either fitted under tension or simply does not reach, forcing a compromise on the install that causes problems later. The right length sits with a gentle curve, not a tight bend, and not stretched taut.
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.
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, trade plumbing supplies 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.
A braided hose is built around an inner core, usually rubber or PTFE, with an outer layer of woven stainless steel strands wrapped tightly around it. That braid does not stop the core from ageing, but it does two useful things: it takes on most of the mechanical load and abrasion resistance, protecting the inner core from damage, and it gives a visible early-warning sign if something is wrong, since a failing braided hose often bulges or shows a strand starting to fray before it lets go completely. Rubber hoses tend to fail with far less warning.
The kilowatt rating printed on an electric shower's box is the single number most buyers look at first, and it is also the most misunderstood. A higher kW rating does not mean a more powerful shower in every sense; it means the unit can heat a given flow of water through a larger temperature rise. Those two things, flow rate and temperature rise, are locked together by the electrical supply available, and pushing one up necessarily limits the other.
This is a common issue on properties that have had a cylinder swapped out at some point without the heater or immersion being reassessed against the new capacity, or where a replacement part has been fitted on availability rather than on matching the original specification. The parts most often involved in correcting it are the immersion element itself, sized correctly in kW for the cylinder's litre capacity, the thermostat controlling it, and occasionally the cylinder's internal coil where a heater draws on indirect heating rather than a direct element.