Mirage Watercoolers provide two types of water coolers, bottle fed and mains fed.
Bottle fed coolers all have gravity based dispensing from a reservoir. Mains fed coolers can have the same as bottle fed but can also have a ‘direct chill’ mechanism which does not involve a reservoir.
The fundamental difference between these two dispensing methods is a matter of capacity. With a reservoir based cooler the literal capacity of chilled water depends on the size of the reservoir. In other words as the reservoir empties of chilled water it then fills with ambient temperature water either from a bottle or the mains. This ambient water then takes a while to chill inside the reservoir.
In times of high demand (large numbers of users/hot weather) a reservoir based cooler can struggle to keep up with the chilling of ambient water, indeed the impression may be given that the cooler is not chilling when in fact it is.
A direct chill, mains fed cooler largely speaking does not have capacity limitation when it comes to chilling.