January 28, 2015

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Kit Review: Rocket Giotto Premium Plus V3

So this is the updated Premium Plus model from Rocket Espresso Milano. The PP has always been an easy to use, solid machine which utilises the traditional HX design, and as with all Rockets, features the iconic E61 group & lever mechanism.

The Rocket range is known for being sleek & stylish whilst producing great quality coffee, and this machine is no exception. In fact, aesthetically the V3 is identical to the V2. What is the difference then? What have Rocket included in the update? That would be this:
That's right, Rocket have added a PID Controller to their HX Premium Plus. We know from experience that HX machines need cooling flushes. This machine is no different in that regard, but the PID offers much more precise control over boiler temperature (and in turn, boiler pressure) than a standard Pressurestat could ever offer. The reason for this is that a PID controller uses a series of parts that can read temperature in a more accurate way. These parts are; thermocouple, a solid state relay and the PID controller unit itself.

"A thermocouple is a temperature-measuring device consisting of two dissimilar conductors that contact each other at one or more spots. It produces a voltage when the temperature of one of the spots differs from the reference temperature at other parts of the circuit."

HX machines without PID controllers use Pressurestats to control boiler temp. 

This is a mechanical part which relies on the boiler pressure physically opening and closing a set of contactors to complete or break the heating circuit. These parts are much less accurate and always have what's known as a 'dead band' or 'swing' where the boiler temperature falls too much before the heater is told to heat. Similarly when the boiler is approaching the target temperature, the heater is not switched off early enough and so the temperature is overshot. PID's aim to eliminate this swing, by sending power to the heater in short pulses so as not to overshoot target temp and keep the temperature as stable as possible.
The V3 uses all the same parts as the V2 with the exception of the PID set up, so you can expect the same build quality and reliability, with improved temperature stability and no 'swing'. A short cooling flush is still recommended, but these are never required to be very big. 
The PID displays 120 degrees celcius - this is the actual water temperature within the boiler, not the temperature of the water at the group. We know that this is too high to brew coffee, but the heat exchanger and thermosiphon work to bring the temperature down to around 94 degrees at the group. You are now able to adjust this temperature in 1 degree increments, giving you more control over water temperature.

All in all, this is a fantastic value machine. Beautiful Italian styling; accurate temp control and above all great coffee.
Contact us to arrange a demo or for more information: info@machina-espresso.co.uk / 0131 229 3495

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