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People have been asking how we got to where we are with the Über Boiler from a design perspective. Here it is –

The Über Boiler’s journey to date was a Bauhaus-type trawl. Function first – form second.

Once we established that premise, we went after temperature stability as the primary goal. We had received a pretty picture from Stephen Morrissey with Square Mile’s vision of how it might look. [Sorry the quality is so bad. The original is somewhere?]

Stephen Morrissey's first sketch of Square Mile's vision.
Stephen Morrissey's first sketch of Square Mile's vision.

After initial brainstorming, the engineers played with existing systems – mixing pressure boiler 100ºC water with cold, using atmospheric-pressure water heaters with finer control and so on.

The mixing of the hot and cold had big issues, predominantly with the amount of time needed to set the machine to the right temperature resulting in significant water wastage (not good) and all round unsatisfactory performance. We messed around with our own machines also and found the drop from tank to tap pretty significant – the initial 2 seconds or so was way under temperature and from then on, there was a pretty consistent gap of 2ºC. That initial ‘cold spell’ could be 60ml of water at the wrong temperature – not good. See the chart below.

Example of temperature profiling, charting the tank to tap losses over a 300ml dispense in 7 seconds.
Example of temperature profiling, charting the tank to tap losses over a 300ml dispense in 7 seconds.

More playing and testing ensued and a mix of Mechanical Engineering wizardry by Peter, allied with some smooth hardware/software befuddlement by Maciej, resulted in the joy of a 500ml pour at +/- 0.2 ºC from first drop to last. Yay! I’m sorry but I can’t give away the crown jewels of the actual how-did-they-do-that.

Next up was the job of the aesthetics. Form followed function, but it still had to look nice as the original brief was for a unit to be used in a café environment, not just a back of house roastery. I wanted this thing to be a slick piece of design. For the first prototype, a ripped apart Salter scale and off-the shelf thermometer had to be housed and made fit. I also wanted the unit to be visually substantial. The challenge was to reflect somewhat Square Mile’s requirement with the physical needs of the machine, while suiting our manufacturing processes in our factory in Dublin. Here is a scan of my sketches which were ultimately to become the first iteration of Über boiler.

The Concept Sketch
The Concept Sketch

This first iteration Mk1 as shown in CATEX last month had a few bits I wanted to fix before installing into Square Mile’s Roastery, namely:

  • Temperature – James’ spec’d 90 ºC to 96 ºC as the temp range, with 90 ºC as the base temperature. I wanted a quicker return from max temp to base temp after a 500ml draw-off. I also wanted to minimize the delay between each temperature setting.
  • Drainage – I wanted to integrate a drain into the unit to avoid trips to the sink. What we’ve come up with is, if I say so myself, Se-weee-eeet.
  • Construction – I was a bit unhappy with the rigidity of the countertop unit. It needs to be solid to take the abuse of a catering environment.
  • No batteries included! – That first unit ran the weighing scales from batteries. Not a real-life option. I wanted all the power to be linked to 13a plug-in for ease of install.

So now – we’re at Mk2 with all the above incorporated which we will install tomorrow. Plenty more improvements due, but I want James and Anette to play with the unit and beat it up a bit. Their feedback and the Atlanta feedback will give us Mk3, which will be shown at Caffe Culture in London in May. I’ll post about the install with pics from Square Mile Roastery later in the week.