Author Topic: Temperature routine for 2015 Gaggia Classic with the steel boiler  (Read 14194 times)

Offline tdfg7583

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Hello all.

What's your temperature routine with the 2015 Classic? I'm having trouble keeping a stable temperature from shot to shot. As my second shot is coming out more sour often, it has made me wonder about the wisdom of flushing some hot water through the grouphead to force the boiler back on before pulling my shot. Maybe this is just leading to an influx of cold water and undermining my efforts to keep the temperature up?

I am only using it for espresso so have not been using the steam function.

My routine is:

- Preheat machine for at least 15 minutes with portafilter and basket in place (normally more like half an hour, if I can be bothered to keep turning it off/on every 8 mins to avoid the auto-shutoff for that long!)
- Run a blank shot until the Brew switch light goes out to trigger the boiler
- Remove and portafilter, dry basket, fill and tamp.
- Run a little more water to switch on the boiler again and then start my shot as soon and the Brew switch button comes on again.

What I'm wondering is, does all that running of water before the shot just bring cold water into the system and make things worse? I think that the Brew light comes back on after the heating is at the peak of the cycle but I guess that's the temperature at the boiler wall? Will it take some time for the new water drawn into the boiler to come up to temperature; i.e. should I wait a little after the light comes on to pull my shot?

I know there is a lot of advice around the internet for Gaggia Classics and temperature but most of it is for the old model and so the larger capacity 2015 stainless steel boiler might change things quite a bit, I suppose?

What's you routine for achieving a good brew temperature throughout a shot and ensuring consistent repeatability. 

Offline JojoS

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Re: Temperature routine for 2015 Gaggia Classic with the steel boiler
« Reply #1 on: December 19, 2016, 09:01:43 PM »
I don't have hands on experience with temp surfing the 2015 Classic but I would suggest that you don't run water before pulling a shot. You might benefit from observing the dead band time of the brew tstat and time your start of brewing accordingly. Please keep in mind that I personally found temp surfing super frustrating and very early on did a PID mod on my old Classic.

Offline tdfg7583

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Re: Temperature routine for 2015 Gaggia Classic with the steel boiler
« Reply #2 on: December 20, 2016, 02:20:03 AM »
Thanks. I watched the cycle this morning and waited about 18 mins for the boiler to kick back in again. If the cycle is that long, it's going to be a real pain timing a couple of shots before work!

I would love a PID but have a couple of problems. I'm not technical and have barely changed a plug recently. I would have no confidence in taking the machine apart and modifying it with electronics components. And I've not found anybody local who'd take on the job for me. Secondly, the kits out there are mainly for the old Classic.

Offline jerryseabridge

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Re: Temperature routine for 2015 Gaggia Classic with the steel boiler
« Reply #3 on: December 20, 2016, 06:35:21 AM »
The stainless steel boiler holds around 200ml of water - approx 50% more than the aluminium boiler. Even so running a standard 60ml double shot will mean replacing around 30% of the hot water with cold water. It will take time for the water to thoroughly re-heat (the stainless steel boiler also has an internal heating element which in theory should re-heat the water faster than external elements). On the aluminium model tests show that to reach full water temperature equilibrium requires at least five minutes between shots. There's not been much research on temp stability on the steel version but it will almost certainly still require a few minutes to stabilise.

All the above means it's still best not to draw off water from the boiler just before a shot.

It's also worthwhile remembering that the tstats are always very accurate so it's all about trial and error - I'd try without purging any water first, then try with a short purge if you're not 100% happy with the shot and see if the resulting brew is more sour/bitter and go from there and try different amounts of purging and time delays. FWIW I would guess that no purging will produce the best results (after all these arent HX machines, they arent meant to be purged) but in the end it's your taste buds that count. If you do some trials please report back and let us know your findings/preferences!

Jerry

Offline tdfg7583

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Re: Temperature routine for 2015 Gaggia Classic with the steel boiler
« Reply #4 on: December 20, 2016, 08:27:15 AM »
I did some test of water temperatures into the cup, just to get a rough idea of the potential variation I was looking at.

Testing with a simple digital thermometer and 2oz of water, straight into a cut-down styrofoam cup, the water varied between 90.3 degrees (Celcius), taken straight after the light comes back on, down to 79.8 degrees C at it's worst (before the boiler kicked in again). This was without purging and with at least 10 minutes between test. The brew light was on for all tests, indicating that the machine was ready to make espresso.

That struck me as a surprisingly large band and so it appears to me that timing will be essential (and annoying) to get anything like even very approximate consistency out of my machine.

I know that's nothing like scientifically rigorous, but it does strike me as a bit disappointing that the temperature control is that imprecise. A 10 degrees C seems a lot, considering it's not the cheapest machine out there.

Offline SusanJoM

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Re: Temperature routine for 2015 Gaggia Classic with the steel boiler
« Reply #5 on: December 20, 2016, 11:13:53 AM »
That struck me as a surprisingly large band and so it appears to me that timing will be essential (and annoying) to get anything like even very approximate consistency out of my machine.

This has always been the case with Gaggias.  Searching for the sweet spot in the 'dead band' has proved futile for most of us, which is why Gaggia owners are often motivated to add PIDs to their machines.  It takes the guess work out of what was temp surfing misery.
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Offline jerryseabridge

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Re: Temperature routine for 2015 Gaggia Classic with the steel boiler
« Reply #6 on: December 20, 2016, 11:37:15 AM »
I second what Susan wrote - I have a feeling that the quality control on tstats isnt great, some seem to have a greater deadband than others - I've seen worse than 10C tbh.

You could keep trying testing the temperature of the water as the ready light comes on - it's likely the machine may also over-shoot 90C - tstats are like trying to drive a car at a given speed x by pressing the accelerator fully until x is reached then removing the foot from the accelerator entirely until the speed drops below x (and in many cases "x-a" where "a" is the deadband) then fully pressing the accelerator again.

It's not just Gaggia SBDUs that suffer from this, similar machines, eg Rancilio Silvia, also use the same type of tstat technology.

Jerry

Offline tdfg7583

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Re: Temperature routine for 2015 Gaggia Classic with the steel boiler
« Reply #7 on: December 20, 2016, 11:52:20 AM »
That's a real shame then. Thanks for the opinions though. Are there any resources out there for adding a PID to a European 2015 model? Has anyone on here done it already?

Offline tdfg7583

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Re: Temperature routine for 2015 Gaggia Classic with the steel boiler
« Reply #8 on: December 20, 2016, 12:06:52 PM »
Even without a PID, I just wish there were some way to kick the boiler into life, to get it to the top of the cycle on demand, without pulling a blank shot.

Offline SusanJoM

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Re: Temperature routine for 2015 Gaggia Classic with the steel boiler
« Reply #9 on: December 20, 2016, 12:41:48 PM »
Pulling a blank shot is just going to bring cold water into the boiler....at which point you have to start all over warming that water...It is definitely not the way to get the boiler water to the right temperature.

The 'ready' light will indicate when the temperature has hit the 'correct' temp for brewing.  That will turn the heaters off, but the temperature will keep rising until it peaks and then will start coming back down.  At some point it will get low enough that the machine will no longer be ready.  The heaters will kick back in, as the lights indicate, but the temperature will still decline further until it starts back up again. 
Temp surfing means trying to find the place within that 30-40 degree deadband to pull the perfect shot.

Pulling a blank shot just cools the hot water you just heated up in the boiler....Shooting yourself in the foot as it were.





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Offline tdfg7583

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Re: Temperature routine for 2015 Gaggia Classic with the steel boiler
« Reply #10 on: December 20, 2016, 12:58:29 PM »
Exactly, that's why I was dreaming of a way to start the boiler *without* pulling a blank shot. i.e. to get to the top of the heating cycle without sitting watching it and waiting for the best part of 20 minutes. Pulling a blank shot does give me near enough consistency  on demand (to within a degree or two), it's just a shame that it's consistently bad ;)

Offline JojoS

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Re: Temperature routine for 2015 Gaggia Classic with the steel boiler
« Reply #11 on: December 20, 2016, 05:38:25 PM »
Not sure if the steam switch blip will be effective on a stock 2015 Classic but that will be worth a try.

Offline tdfg7583

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Re: Temperature routine for 2015 Gaggia Classic with the steel boiler
« Reply #12 on: December 20, 2016, 06:11:00 PM »
I thought about that to raise the temperature but, not knowing the starting point in the 18-odd minute cycle, I don't know if I'd be boosting it to a similar temperature each time?

Offline JojoS

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Re: Temperature routine for 2015 Gaggia Classic with the steel boiler
« Reply #13 on: December 20, 2016, 07:56:19 PM »
Ahh yes the starting brew temp only a PID setup can regularly provide. Since you are in the UK, the go to guy is MrShades. He might be able to put a PID on your rig.
« Last Edit: December 20, 2016, 10:22:50 PM by JojoS »

Offline tdfg7583

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Re: Temperature routine for 2015 Gaggia Classic with the steel boiler
« Reply #14 on: December 21, 2016, 12:44:52 AM »
Thanks for the suggestion, but I did try MrShades soon after getting the machine. Apparently his kits only work on the older Classic, not the 2015 Euro version, there's not a new version of the kit coming any time soon and he couldn't help me with it, unfortunately.

 

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