Hi.
Just noticed this thread although its old.
Its interesting as I have been working on a design of my ideal machine.

I have established brew water temperature variation affects taste greatly, I can definitely taste 2 deg. C difference and think I can taste 1 deg.
With the thermal analysis posted here can the poster advise the heat loss (radiant?) used.

Thanks,
steve

I lost the model in a hard drive crash, so I cannot give you much detail. The heat loss from the model is about 15 watts, which did not include radiation loss. I have some information on a spreadsheet, if you are interested.

-Bruce

Thanks.
I am contemplating using a couple of 40w ceramic soldering iron elements inserted into holes drilled through the group head to control temperature. Obviously more than adequate to cover the 15W heat loss. Could probably drop it to 2x 20W.

This is such an educational original post by Lino that I thought it needed to be brought to the forefront again. If anyone is working on a thermal model and needs some temperatures to corroborate what you read, just drop a line.



Any correction on the part names is welcome and, obviously, not all gicleurs are 0.70 mm but hey, what's a few tenths among friends?

Eric S.
erics@erols.com

Lino and I have been talking on and off about an article featuring these diagrams for the last couple years. We're still talking about outlines and diagrams. To be honest, I'll be pleased if it's finished in 2007. In the meantime, below is a test video of the E61 in action.

«missing video»

bruce wrote:lino,

I created a crude thermal model using your pictures. I am sure someone has done this, but I thought it would be fun to try. The results show a 10 degree (F) drop to the tip of the group head.
<image>

I wonder why we construct the grouphead with a highly thermally conductive material that constantly leaches heat energy away from the brew path. What would happen if we used a ceramic material to provide greater temperature stability in the brew group.

I've been wondering for a year or two whether it would be possible to create a temperature probe that screwed into the Closure Plug and measure the temperature that feeds into the top of the group head. It seems to be the nearest point of entry to the puck that could be measured and would show the least amount of external influence by the actual puck etc.

I imagine if it could be made to work in this method, it would be very cheap to produce and give a secondary measurement technique for debugging heat issues along with the Scace device.

Thoughts?

jamver wrote:I've been wondering for a year or two whether it would be possible to create a temperature probe that screwed into the Closure Plug and measure the temperature that feeds into the top of the group head.

See Monitoring Brew Temperature - E61 & Silvia.

Or if you are feeling particularly handy and have lots of time and patience, No More Guesswork! Naked Truth of E61 Temperature Revealed. Eric's adapter is far easier and the thermocouple version is much more accurate. I use one of his adapters when testing.

Question for Bruce please,
are the thermal reading from your drawing taken during extraction or idling?
thanks
S