I have started looking at my EM6900 thermoblock based machine. It is based on the Sunbeam EM6900 stainless-steel lined thermoblock. I have mated it to a Bezzera BZ35/99/02 group and installed a 3-way solenoid valve. This is slightly different to how Sunbeam have used this thermoblock. In the EM6900 machine, the thermoblock forms the top of the group giving rapid heating of the group. It also uses a separate exhaust port, rather than a 3-way valve. While these are excellent design features, they were not practical to implement in my machine. Nevertheless, my machine is useful in exploring the core technology and capability of this thermoblock.
The first thing I noticed is how fast the thermoblock comes to temperature. It only takes a few minutes. In the actual EM6900 machine with the bottom of the thermoblock forming the top of the group, this means the machine will come up to heat far quicker than anything else out there.
I have started using this thermoblock in a mode very similar to the Sunbeam heating mode. That is a K-type thermocouple mounted in a thermowell next to the input to the thermoblock. This means the temperature control will respond rapidly to the cold feed water. In practice the controller is in on/off thermostat mode and it responds instantly to the cold feed water by turning the element full on during the course of the shot.
Here are a series of 3 successive 60 ml shots taken as fast as I could log them. I am using a thermofilter-type device which has a K-type thermocouple probe mounted just under the shower screen and an adjustable flow valve in order to simulate single shots, double shots or anything in between. It is important to measure the brew temperature of a thermoblock at proper brewing flow rates as the thermoblocks ability to heat is very dependent on the flow rate through the block. What I noticed is that the thermoblock responds rapidly to the cold feed water and is capable of bringing the water up to brew temperature at a reasonable brewing flow rate. In fact the temperature actually climbs during the shot, indicating that the element has more grunt than necessary. However this extra grunt results in relatively poor intra-shot stability with a 4 C variation in the shot. In contrast the Silvia is capable of less that 2 C variation, especially when fitted with a PID controller. However, this is at least on par or better than a Gaggia, although the Gaggia profile falls rather than rises.
So the bottom line for the EM6900 brew thermoblock is that it is capable of maintaining proper brew temperatures during a shot. Add to that the ultra-fast heat up time and the separate pressure exhaust port (which keeps the brew circuit clean) and you have a potentially killer technology.

The first thing I noticed is how fast the thermoblock comes to temperature. It only takes a few minutes. In the actual EM6900 machine with the bottom of the thermoblock forming the top of the group, this means the machine will come up to heat far quicker than anything else out there.
I have started using this thermoblock in a mode very similar to the Sunbeam heating mode. That is a K-type thermocouple mounted in a thermowell next to the input to the thermoblock. This means the temperature control will respond rapidly to the cold feed water. In practice the controller is in on/off thermostat mode and it responds instantly to the cold feed water by turning the element full on during the course of the shot.
Here are a series of 3 successive 60 ml shots taken as fast as I could log them. I am using a thermofilter-type device which has a K-type thermocouple probe mounted just under the shower screen and an adjustable flow valve in order to simulate single shots, double shots or anything in between. It is important to measure the brew temperature of a thermoblock at proper brewing flow rates as the thermoblocks ability to heat is very dependent on the flow rate through the block. What I noticed is that the thermoblock responds rapidly to the cold feed water and is capable of bringing the water up to brew temperature at a reasonable brewing flow rate. In fact the temperature actually climbs during the shot, indicating that the element has more grunt than necessary. However this extra grunt results in relatively poor intra-shot stability with a 4 C variation in the shot. In contrast the Silvia is capable of less that 2 C variation, especially when fitted with a PID controller. However, this is at least on par or better than a Gaggia, although the Gaggia profile falls rather than rises.
So the bottom line for the EM6900 brew thermoblock is that it is capable of maintaining proper brew temperatures during a shot. Add to that the ultra-fast heat up time and the separate pressure exhaust port (which keeps the brew circuit clean) and you have a potentially killer technology.





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