Talking Hot Water

Variable temperature hot water dispensers.

This has been promised for a while. For any of you who have had the misfortune of meeting me, the topic will come as no surprise.

Just a quick intro. Some teas are brewed at near boiling point. Others are brewed at around 60oC. The ability to brew different teas, quickly, in a café environment, is the subject of this post.

At the teahouse we have two different boilers, one set at 98oC, the other set at 78oC. These effectively deliver 95oC and 75oC onto the leaves when we dispense. For our Japanese greens we add filtered cold water to hot water. To achieve 80, 85 and 90oC we measure, mix and pour. As we have been operating for over three years this process has become streamlined and fast. Although new members of staff have to be given full training on the techniques involved.

Other teahouses employ three boilers – 75, 85 and 95. The practice of always adding cold water to hot water in a busy environment is impractical. It can be done in slow paced cafes, but it is certainly not laying foundations for success.

I have been researching into variable temperature hot water dispensers for a number of years. The ideal solution would deal with

a)      Footprint – although having three of four boilers set at different temperatures provides a solution, it is not viable in many café settings. The preferred piece of equipment would reduce the space required to deliver the variable temperatures.

b)      Temperature accuracy – an accuracy of plus or minus 1oC is a good benchmark to aim for. This would mean than teas would be brewed within a margin of 2oC. This is perfectly acceptable for tea. Obviously, even more accurate would be welcomed.

c)       Output time– the required temperature should ideally be available at the touch of a button. Waiting while the font is primed for a set temperature is acceptable, only if it is less than a 10 second wait. If there is a wait of a minute or so, then procedures could be adopted where temperature is set, tea is weighed out, and the boiler returned to when ready. This is do-able, but not ideal.

d)      Output temperature and volume – Most teas you will find are brewed at the higher end of the scale, closer to 95oC. However, it may be the case that a place specialises in green tea, which would be using temperatures in the range of 65-85oC. The ideal solution would allow users to specify what range they would be mostly using, and for the equipment to be created with that in mind. This is of note if the solution comprises of different temperature boilers linked to the output font. The most commonly used temperature could be held in a larger tank than less commonly used temperatures.

e)      Water loss – there are some delivery systems available which allow users to set the temperature. These are often useful when increasing temperature, but when reducing temperature it necessitates the hot water from the tank being drained to allow an influx of cold water from the mains – cooling the overall water temperature. This flushing of water is not acceptable from an environmental viewpoint.


Possible Solutions

The obvious solution would seem to have one hot water tank, with a cold water inlet from the mains. This could mix and merge with the hot water, creating the temperature desired. One point that needs to be considered is the temperature of the inlet water. This needs to be monitored, and perhaps heated to a certain temperature – allowing the software used further down the line to mix known entities. Alternatively, this temperature could be monitored and adjusted further down the process, with a priming technique.

Having a 95oC boiler and a 65oC boiler, which can be mixed by the machinery and dispensed would be another option. Although perhaps more of a footprint involved, it would still take the manual mixing out of the equation.


Commercial Aspect

A variable temperature system would change the face of the tea world. Excellent teas could be brewed to perfection, at the touch of a button. No longer would you think twice about ordering a Japanese Sencha. Tea is potentially the biggest growth sector in the café world, and an already established feature of many fine hotels. By having a such a system, tea could be delivered consistently, and the ‘human error’ aspect of the brew process eradicated, to a certain degree.

In the coffee world it is perfectly acceptable to spend £4k-£9k on an espresso machine, and in excess of £1k for a grinder. If a new hot water delivery was available, and marketed as an essential component of an effective tea service then sales for manufacturers would justify the investment.

How much should it cost? To achieve accuracy, the cost will be high. Having the obvious ability to double up for brewing coffee, then we would expect to pay between £1.5k-£3k.




Feel free to add , or disagree. I have purposefully not mentioned any manufacturers.



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