Reservoir vs Direct Chill in Plumbed Water Coolers

Wednesday, 4 January 2017  |  Admin

Mains water coolers come in two variants: direct chill and reservoir. So what's the difference?

Reservoir Water Coolers

With a reservoir-type water cooler an insulated tank contains the water, and the water in this tank is chilled.

Consequently, the temperature of the water dispensed will depend on the hourly volume and the turnover at peak times.

For example, if you have a large number of people who are all accessing the water in a short time period. The first batch of people will all get nice ice-cold water. However, if they half-empty the tank, then the system may not have had the opportunity to fully chill the water before the next batch of people take water, and therefore their water won't be quite as cold.

With a reservoir water cooler the tank is constantly being partially emptied and refilled, so the only way to fully guarantee that some of the water hasn't been in there for some time is to totally empty it. Consequently, if your company is closed for periods of more than a few days then your water will have been sitting in the tank for this period of time.

Direct Chill Water Coolers

There is no industry-standard name for this type of cooler, with different manufacturers calling it by different names (Ice Bank, Direct Chill, etc.). We just call it Direct Chill throughout our site to make it easy for you to find a water cooler using this type of technology.

With a Direct Chill Water Cooler there is no reservoir.

Instead the pipe running from your mains water supply to the dispensing tap is coiled within a bank of ice and is chilled that way.

What this means in practice is that the temperature of the water is always guaranteed. There will always be a small variance because of the temperature of the mains water supply. The Direct Chill system will cool on average 20 Litres of chilled water per hour at times of high turnover.

Another important reason people like direct chill water coolers is that of hygiene.

With a direct chill water cooler there is no reservoir for the water to lie in, so if your company closes for more than a few days a direct chill water cooler will actually pay for its additional cost very quickly, in terms of sanitizing fluid and staff time.

Schools, in particular, are highly recommended to use a direct chill water cooler to allow for closures at half-term etc., and direct chill water coolers are the only ones approved within the NHS for hygiene reasons - neither bottled water nor reservoir water coolers are permitted particularly on surgical wards.

Summary of Reservoir vs Direct Chill

Reservoir Direct Chill
Water temperature can vary at times of peak turnover Water temperature is constant
Not suitable for premises that close for more than a few days: Will require sanitizing after non-use for an extended period, e.g. school summer holidays Because there is no reservoir for water to stagnate in direct chill water coolers are perfect for schools and hospitals.

Direct Chill Technical Video

This brilliant Borg and Overstrom video explains - far better than we ever could - how a direct chill water cooler works:

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