When does an evaporative wick really need changing?
Updated 2026-09-24
Short answer
When output drops at an unchanged fan speed, or when the wick has gone stiff and chalky white. The calendar interval makers publish — usually one to three months — assumes average water. On hard water a wick can be done in three weeks; on soft water it can run most of a season. Judge it by stiffness and output, not by the date you installed it.
What is actually failing
Every mineral that does not leave with the vapour stays in the wick. Over weeks the pores fill with scale, the wick stops drawing water up, and the wet surface area collapses. The fan is still running at the same speed and the unit looks fine — it is just moving far less water than it did in week one, which is why the humidity reading quietly slides.
The stiffness test
A fresh wick is soft and flexible. A finished one is rigid and pale with crusted edges, and will not compress between your fingers. That transition is unambiguous and takes two seconds to check, which makes it a better trigger than any interval.
Can you clean one instead?
Partly. Soaking in white vinegar or a citric acid solution dissolves some scale and recovers some flow, and plenty of owners get an extra few weeks that way. It does not restore a wick that has gone rigid, it is messy, and most makers decline to endorse it. Treat it as a way to stretch a wick, not to avoid buying them.
Budget for it before you buy
Wicks are the running cost that decides whether an evaporative is cheap. A single-wick unit runs $20 to $30 a year; a two-wick unit doubles that; a console working hard on hard water can go through three at $20 each in one season. Every unit in this catalog carries its own estimate with the arithmetic behind it.
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