I am trying to figure out the optimal time in the Classic's boiler temperature cycle to pull a shot. There is really not much sound to go by and I am not sure if the red light on the brew button indicates anything much. How can I figure out the best point to pull my shot, and also the least complicated method of figuring out that moment?

All replies appreciated.

EspressoGirl

HB will post a link to the Gaggia group in 5.4.3.2....

The best time to start the shot will depend on the coffee you are using and your taste preference.

When the brew light goes off, the heating element cycles on and begins to heat the boiler. When the boiler comes up to temp the brew light comes back on indicating the machine is ready. At this point it is as hot as it will get and is starting to cool off. I suggest you start here. Pull the shot immediately after the boiler cycles and the brew light comes back on, and start adjusting from there.

If the shot tastes like the water was too hot you can employ a couple of different things to achieve a lower starting temp for the shot. You can either wait a set amount of time after the boiler cycles off allowing the boiler to naturally loose some heat, or you could use a damp rag to wipe down the shower screen for a few seconds to reduce the initial shot temp. Because the boiler is so small I would not suggest doing any cooling flush as even a small flush will upset the boiler temp and you will likely not be able to reproduce a consistent volume for a cooling flush.

If the shot seems sour because it was too cold at the start, you can flip the steam switch for a set time after the boiler cycles to bring the element back on and increase the boiler temp beyond the brew thermostat.

It will still take some trial and error on your part to get an idea of what works best for you and your coffee, but this is where I would start. Taking notes also helps to get an idea of what is going on.

Thanks Gus,

What did you mean about HB posting something (is that a joke I didn't get?)

Some more questions related to your answer:

1)You said flushing water is a bad idea. I always run some water through the group and into my cup before I go fill my basket with grinds to pull the shot. I do this both to heat the cup and (I thought) to make the grouphead hotter (does it?) At the very least, I need a hot cup to hold espresso while milk is steaming and the passive top heater is a joke. So do you think running that water through the group is bad? Of course, if it is, I guess the same thing happens every time you pull a shot -- so maybe I don't understand what you meant by the cooling flush and maybe what I am doing is fine... I can just wait for the red light to go on again, which happens fast, to indicate top temp is reached, right?

2)Is is ok for me to attach my PF to the machine and then wait for the red light to go on (highest temp)? Or should I not attach it until it is at that temp?

Thanks,
Sarah

No it wasn't a joke. I thought Dan would post a link to the Yahoo Gaggia user group found here http://groups.yahoo.com/group/Gaggia/

There you will find nearly everything you want to know. You have to join the group to access the information they have, but they have a lot of information.

Flushing water is not bad, as in it will not hurt your machine. I try to allow the water to sit in the boiler undisturbed for at least 5 or 6 minutes before pulling a shot. (Two boiler cycles)The reason I do not flush the Gaggia is that it only has a 3.5 oz boiler which is very small, and the thermostat is mounted externally on the boiler wall. What this means is the thermostat is reading the temperature of the boiler wall and not the water inside. This is proven by the very short initial heat up when you first turn the machine on. The side wall of the boiler heats up very quickly because the boiler coils are embedded in the boiler wall. The heat transfers along the boiler wall to the thermostat and cycles the boiler off. The water on the inside however is not actually at brew temp. It will quickly cool the boiler wall and the heating element will cycle again. The longer the water sits in the boiler the more stable the temperature becomes. Keep in mind any water you draw out of it is replaced by room temp water that will upset what is already fairly poor intrashot temp stability. It is so poor that I don't think you can even consider the term when discussing a Gaggia. That does not mean it is a bad machine. I produce very nice strait espresso with my machine I just heat my cups with water from a kettle or with tap water and the microwave.

The group head on your machine is attached to the base of the boiler. It has the entire boiler volume sitting just above it, so it is not really necessary to heat the group prior to pulling a shot. If you fill your cup from the boiler and your cup is larger than 3.5oz you completely empty the boiler and replace the hot water that was inside it with room temperature water. This will ultimately cool the boiler causing the element to cycle again, and it will take 2 or 3 boiler cycles to stabilize again after completely draining the boiler. Sit around with a stopwatch one day and record the boiler cycles after the machine has heated up for 15 minutes. After recording a few cycles pull a full cup of water and record the boiler cycles again. You should find that after heating up for 15 minutes it takes between 4.5 and 5 minutes consistently between boiler cycles. After you pull a cup of water the heating element should begin to cycle before you finish filling the cup, then again in about a minute to a minute and a half, then again in another 2.5 to 3 minutes. I have noticed it can take as many as 4 or 5 boiler cycles of undisturbed water to reach a cycle rate greater than 4 minutes. To me this cycle rate represents the machines peak stability.

As for locking the portafilter and waiting for the boiler to cycle before pulling the shot, I personally would not do this. It could overheat the coffee grounds and leave an ashen taste in the cup. I find that after the boiler cycles the shower screen is hot enough to flash boil the first bit of water that comes out. This would easily be hot enough to affect the taste of the shot. To remedy this I simply wipe the shower screen down for a couple of seconds with a cool damp rag before I pull the shot.

This is what I do with the coffee I am using for my taste. You may find that your coffee tastes better at a hotter or cooler start temperature than what your machine provides with the thermostat. In that case you can either pull a measured cooling flush or flip the steam switch after the boiler cycles for additional heat prior to pulling the shot.

I hope this is helpful in some way.

Gus,

I asked Gaggia Tech People (now located at WLL no matter where you bought it) about the temp cycling on the Gaggia Classic related to the red light on the brew switch. Here is the reply I got (they have it backwards, no?):

The machine is at its hottest when the heating light goes off. The heating elements are on when the indicator light is on. When the light turns off, the boiler has reached its operating temperature.


Please let us know if you need further assistance.

With Regards,
The Technical Support Department

Just want to make sure I understand it. Based on what you said, machine is hottest right after red light comes on, and when light goes off it is really at its lowest and starting to reheat, right?

Thanks for the Yahoo group tip and all the rest!

Sarah, when you first turn the machine on, the heater light goes on, right? If this is the case, when it goes out the boiler is at max temperature.

Sarah -

The following graph probably will not answer your question completely, but should help. I did not record the temperature when the thermostat switched and turned the heater off, i.e., when the light came back on. A good estimate of that switching temperature, however, would be 10F to 15F lower than the peak temperature.

The graph shows that the "rise" time for the Gaggia boiler is ~22 seconds. During this time, the temperature rises ~49F. So, on average, the boiler temp is increasing by 2.2F every second during the heating phase of the cycle. Based on this, I would estimate that the peak temperature occurs 5 to 7 seconds after the heater turns off.

The graph also shows that the cycle time, when everything is fully warmed up, is approximately 285 seconds. From this, you can make a gross estimate of the rate of cooling. On average, the boiler cools by approximately 1F every 5 seconds during the cooling phase of the cycle.

Jim

sweaner wrote:Sarah, when you first turn the machine on, the heater light goes on, right? If this is the case, when it goes out the boiler is at max temperature.

No one I have read agrees with what WLL Tech said and I am convinced it is not true. After a good heatup, the temp appears to be between 195 and 200 degrees right after the red light comes on. Everyone here seems to agree that when the red light comes on, the machine has reached max heat and is starting to cool down.

JimG wrote:Sarah -

The following graph probably will not answer your question completely, but should help. I did not record the temperature when the thermostat switched and turned the heater off, i.e., when the light came back on. A good estimate of that switching temperature, however, would be 10F to 15F lower than the peak temperature.

The graph shows that the "rise" time for the Gaggia boiler is ~22 seconds. During this time, the temperature rises ~49F. So, on average, the boiler temp is increasing by 2.2F every second during the heating phase of the cycle. Based on this, I would estimate that the peak temperature occurs 5 to 7 seconds after the heater turns off.

The graph also shows that the cycle time, when everything is fully warmed up, is approximately 285 seconds. From this, you can make a gross estimate of the rate of cooling. On average, the boiler cools by approximately 1F every 5 seconds during the cooling phase of the cycle.

Jim

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Thanks. Does the machine really get this hot? From some of my measurements, I thought that even after steam the water from grouphead only comes out at about 210....

EspressoGirl wrote:No one I have read agrees with what WLL Tech said and I am convinced it is not true. After a good heatup, the temp appears to be between 195 and 200 degrees right after the red light comes on. Everyone here seems to agree that when the red light comes on, the machine has reached max heat and is starting to cool down.

Then it appears the light comes on when the boiler is fully at temp, and is at Tmax.