Steam Pre-Heating Experiment

The Background

The idea is to get a higher shot temperature out of the Forge than would be otherwise easily possible by pre-heating with just boiling water. First introduced on HB by Peter (beananimal) here:

The Setup

The Forge placed ontop of a Fino 1.2L kettle. My Forge has a small hole drilled in the top plate, which fits an instant-read type of thermometer. To get a more accurate temperature, I also added some Dow 111 to act as a thermal compound. Take note, this reads just the overall metal temperature, not exactly the temperature of the water or steam inside the Forge. Idea was to preheat the “group-head” to around 75C, then lock in the basket and pull using normal 100C boiling water to get a shot temp in an expected 80-90C range.

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The Result


By taste, I can tell that the method definitely works to pull better highlights out of lighter roasts. So far, I don’t feel it’s necessary for most dark roasted coffees. The normal pre-heat method by using boiling water gives me excellent results. But to prove it a possibility I wanted to show my findings. Next step will be to get some Scace readings. If I can’t find a customer who is interested in doing this test that already has a Scace, I’ll be looking to pick one up. Anyone interested in loaning me theirs?

4 thoughts on “Steam Pre-Heating Experiment

    • Andre Vornbrock says:

      The hole is countersunk and doesn’t go all the way through. It’s not threaded, but I did have the idea to thread it so that a thermocouple could be screwed on. Overall in testing I’m not sure accuracy is any greater than just fixing a thermal strip to the top.

  1. Chad says:

    Thanks Andre. I love my new Forge. I have just been preheating with boiling water while I grind. I will look for a thermal strip to put on the top. Keep up the good work.

    • Andre Vornbrock says:

      Thanks! Yeah I would suggest the thermal strip if you’d like it to be more repeatable. Steam heating while a bit fiddly is nice in a couple ways beyond just being able to hit a higher temperature. It’s more self-contained and more water efficient. The “whistling” effect also lets me know when it’s getting ready like a teapot. Downside with this kettle is that sometimes needs to be adjusted as it’s heating up to get a good seal. Also, occasionally some water does come out the spout from the pressure building inside. Not sure why it only does this occasionally right now.

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