The Dirty Portafilter

My corner of the Internet, mostly espresso related but occasionally life will interfere.

Wednesday, December 28, 2005

Isomac Millennium Mods Revisited

I made a few more alterations to my Isomac Millennium. Even with the oil dampened pressure gauge, I was getting way to much flutter. This not only renders the gauge nearly useless, but will lead to a speedy demise of the gauge. The constant pulsing will blow the diaphragm out of the gauge. I also wanted to reinsulate the boiler. The pipe insulation I had original used had a very low R value and does not provide adequate insulation.

I managed to find the adaptors to convert my ΒΌ inch T fitting to a 1/8 inch OD pipe, and from the 1/8 inch OD pipe back to the 1/8 inch NPT fitting on the gauge. I purchased 4 feet of soft copper tube and wrapped it around the handle of a screwdriver to create the coil. The smaller tubing, longer length and coils eliminated the entire pump pulsing. The gauge now operates without any flutter

I pulled the pipe insulation off of the boiler. I used some ceramic foil backed insulation I had left over from a wood burning stove installation. I wrapped the insulation around the boiler and end caps. It does not look pretty, but works very, very, good. With the machine heated and running at 1.3 bar, I can put my hand on the foil backing. It is no hotter than a heating pad.

While I was in there I decided to play with the Pstat setting. I have one of the older pstats with the deadband adjustment screw. I gave it a very small turn to tighten the deadband, and made a very slight increase in boiler pressure. I am getting a .05 deadband now. The boiler cycles from 1.25 to 1.3. I found that to be quite shocking. I did not expect any change.

Unfortunately, with the added insulation, the boiler is now too hot. It steams like a champ, 8 seconds to stretch and about 15 to heat, 15-20 seconds to steam total. I have to run an absurd cooling flush and the HX is overheated in just a few seconds (15-20) so I am constantly pulling 8 oz (or more) flushes to cool the unit before extraction. I am almost afraid to touch the Pstat fearing that my nice tight deadband will go away, but it has to be adjusted down.


  • At 8:22 PM, Anonymous Anonymous said…

    Nice bird, and nice PID espresso maker article too.



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