Sunday, May 07, 2006
I am tired... This mod job has taken way more time than I have imagined. In general, I took my time and double/triple check my works. Some mistakes were made, but none are deal breakers. Upon powe up, only 3 leaks were discovered. One at an elbow that I decided to JB-weld it. One at the pressure gauge, which I have re-fitted with some extra teflon tapes. The last leak is at the compression fitting going in the heat exchanger. The tip was cut and a new "bead" was used. Lesson learned - never teflon tape any compression fittings... and make sure you tighten the crap out of it...
The pre-heater loop was a major pain the butt to put in. Bending "soft" copper tubes are not as easy as it seems. I mean, it bends; but if you are not careful, you will "flatten" the tubes. Also, short length and small loops are difficult. The broiler loops are not as tight as I had hope, and only very small parts of each loop is in contact w/ the broiler. This made me worry about it's performance. I put as much insulation as I can all around the broiler/loop. Hopefully this will help its performance a bit. Anyway, what's done is done. I will have to do some measurements to see its performance later this week.
Anyway, I think this finally concludes "Phase 1" of the Rituale Transformation Project, which consists of re-routing all the wires, relocating the controller box, relocating the pump/solenoid assembly, and adding the pre-heating loop (top picture). An machined aluminum braket replaced the orginal internal frame to make room for the relocated pump, which occupied an space alloted for future rotary pump conversion.
Phase 2 of the project will be replacing the current pressurestat with a PID control system. All the parts have been ordered and they should be arriving in the next 2 weeks. Adding these parts should be much easier than phase 1 as all the accomidations for wiring/mounting has been made. It should not take more than an evening worth of work.
If the pre-heater loop + PID works well, I will be looking into replacing the current vibe pump with a rotary pump (phase 3). During my research for the modification project, I have learned that vibe pump is very sensitive to voltage drop. If the heating element comes on while the pump is operating, the output pressure could drop as much as 0.25 bars. This causes the pressure profile to be really jagged and reported to reduce the overall clarity in the cup. Since the PID system will make the heating elements goes on much frequently than the pressurestat, this problem is worsen. However, I hesitate to purchase the pump right away as the miniature version I have spec out is quite expansive (~ $260). If anyone knows another (cheaper) source for the 1/4 HP motor that espresso parts sells, PLEASE contact me and help me save some money!