Solved: temperature control

I am very pleased. For years, now, I have striven to develop a clean and simple temperature control algorithm for my coffee machine which gets it to a stable temperature in the minimum possible time. This weekend, I cracked it: two minutes to a stable 95°C on my Gaggia Baby Class with no oscillations at all1That’s not quite all that is needed – the brew head needs bringing up to temperature as well. But that’s a different topic and I’m still working on it. Two minutes is also not an absolute minimum because the boiler power can be increased. Also a topic for another day. For the purposes of this post, we’ll use the stock 1350W the machine shipped with..

This is how I did it…

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1. That’s not quite all that is needed – the brew head needs bringing up to temperature as well. But that’s a different topic and I’m still working on it. Two minutes is also not an absolute minimum because the boiler power can be increased. Also a topic for another day. For the purposes of this post, we’ll use the stock 1350W the machine shipped with.

Gaggia boiler specs

So, you’re obsessed with implementing the perfect temperature controller for your Gaggia Baby Class (or Classic or any other derived model)1Oh, you’re not: is it just me then?. You’ve realised that you really need to know the values of some important parameters and the only easy way to get those is to take the boiler apart. And you don’t want to do that2Are you sure you don’t? If you do, you can take the opportunity to improve the brew head temperature.. The good news is I’ve done it for you3Where I also took the opportunity to improve the brew head temperature.. Here is everything you need to know4At least, I hope so: I don’t want to take it apart again.: Continue reading

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1. Oh, you’re not: is it just me then?
2. Are you sure you don’t? If you do, you can take the opportunity to improve the brew head temperature.
3. Where I also took the opportunity to improve the brew head temperature.
4. At least, I hope so: I don’t want to take it apart again.

Improving Gaggia brew head temperature

Over recent weeks, I have wasted invested a lot of time investigating the Gaggia boiler thermodynamics. (All part of my master plan to have the entire machine at a stable temperature inside 2 minutes from power on.) A major obstacle to getting a stable temperature quickly is that the brew head takes for ever to warm up. Whilst thinking about this, I hit on an idea for improving the heat transfer from the aluminium boiler shell to the brew head: put heat-sink compound in the join between the shell and the brew head. Continue reading

Mulled Wine

Ingredients

1-2 sticks of cinnamon
1 nutmeg
15 cloves
5ml coriander seeds
5 cardamom pods
300ml orange juice (from 4-6 oranges)
¼ cup brown sugar
300ml water
750ml red wine
150ml cognac

Directions

Put everything except wine and spirit into a pot. (The cardamom needs shelling).

Float empty orange shells on top. (Assuming you didn’t short-cut it with carton stuff).

Simmer until spicy tasting.

Add wine and spirit and heat to almost boiling.

Don’t drink all at once.