nVentiv (also known as Chip-Con) released their first phase change unit back in 2002, called the Prometeia. It offered subzero cooling unlike any other solution on the market back then; When competition raised its head (asetek) they released new units and changed their company name and product line. The Mach II was born, followed by the Mach II GT and Mach II ST. The old Prometeia unit was renamed to Mach I and it is this piece of hardware I’m going to give a power boost today. Webmaster Alex from the Belgian overclocking website Overclex send me his unit for a complete overhaul. [A French version of this article is online at Overclex]

This is how you average run-of-the-mill nVentiv freezer looks like:



All the different Mach revisions used similar hardware, like the Danfoss NL11F compressor:



And the freezing head (a.k.a. evaporator), which consisted of a black plastic box with the evaporator insulted inside with PU foam. The different revisions of the Mach improved performance and while the mounting system was certainly not the best, it got the job done.

Here’s an overview of the different evaporator heads used by the Mach 1 and Mach 2 from nVentiv.



Now I’m not going to talk you through the history of retail phase change units, I’m here to show you how I’ll upgrade nVentiv’s first Subzero machine so it can easily match the Mach II GT and asetek Vapochill LighSpeed performance wise!

Let’s get started ->

So here the Mach I as it was originally sold by nVentiv:



Let’s start by removing all the parts we no longer need, like the old evaporator which I can now decommission. The preinstalled insulation is about 3cm thick – since we’ll upgrade the performance of the unit it might not be enough so I decided to remove it and replace it with thicker insulation to prevent condensation.



I removed all the insulation and removed the standard flexible hose too.



Then the search for the temperature sensor begins, the sensor is deeply buried in the PU foam and glued with some sort of thermal compound to the evaporator.



Digging deeper I found the heatingwire and the thermalpad in the housing.



The search is over, the temperature sensor can now safely be removed




With the temperature sensor tucked away the unit is ready to be serviced ->

For a modification like this one I always take apart the whole unit and braze everything back together afterwards; there are a few things you need to watch out for when you do this, otherwise you might have a hard time putting things back together.

For one, make you spot the thermal sensor which is placed on the inlet of the condenser, this sensor protects the unit from overheating if the cooling fan would fail.




Here’s picture of all the goodies laid out on top of the case



This particular unit has a small leak in the suction hose, this is a weak point of the prometeia unit's.
I started by removing the oil from the compressor. A leak will cause air to be sucked in and form moisture inside the compressor which will eventually lead to a malfunction.



Now let’s put some new Fresh POE oil in.



With the compressor refilled I can start to braze already a few things. Because the stock condenser can’t remove all the heat output generated by the upgraded unit, I am installing a coiled piece of 1/4” copper tube right after the condenser (also named desuperheater).

Without it, when the unit is fully stressed and running inside a warm room, pressure in the unit can get higher than normal. This leads to lower performance and that’s not what we want, now do we?



The condenser is now brazed onto the desuperheater and a piece of copper for the liquid line to the filter/drier is also done.



I moved the filter because it wasn’t placed optimally, in its new place the unit will cool down faster because liquid can easily travel to the filter now.



Next I’ll start working on a new evaporator ->

Getting good performance from your phase-change unit is also determined by the evaporator, so a new one will be connected to it with a nice piece of flexible suction hose.

The design of the evaporator will help performance; this particular model was made by a fellow phase-change fanatic from Germany called Jan.





Here it is after I drilled some holes for the capillary tube and the exit for the vaporized refrigerant.



Next I need to heat it up so I can braze the different parts together



Cherry red means brazing time! So this is what I am going to do now.





To keep the inside clean I purged it so no oxidation can occur.



After some cleaning I ended up with this.

Let’s connect the flexible suction hose to the evaporator; it will be insulated afterwards with 13mm Armaflex closed cell foam. This new suction hose a 10mm internal diameter and 18mm on the outside including the braid.



The end is near; I still need to braze the suction port of the compressor, so here’s an overview of the remaining steps I took:





Reconnected the thermal overheat protection of the unit:



And insulated everything:



Time to find out how it performs ->

The compressor was charged with R507 and ready to be tested, using a dummy load device which allows me to generate up to 200 Watts of heat (4x 50w 1Kohm)

I installed a K-type thermocouple about 1cm into the bottom of the evaporator to get the an idea of the performance, since I ran out of the thermal grease these results are not 100% accurate.

Without load I got -56°C



With 150W heat load : -31°C



At 200W the display came to life and showed -41°C, the thermal probe at the evaporator read -26°C.



Here at Madshrimps Petervandamned did a review of the ECT Mach 2 GT; he also used a dummy load for testing and at ~200Watt load he got -13°C from the evaporator head; The tuned Mach I got -26°C, although my test setup is not the same, to prospects are positive. There are still a few additional tricks which can be pulled of to increase the performance of the Mach I; but that's for a next article.

This particular modification is finished and the unit is ready to be send back to the owner:




How did it work on his P4, check the next page ->

Alex from Overclex shared his findings when he received his refreshed Mach I:

Alex's System
CPU	Intel P4 630 – 3.0Ghz default
Cooling	Jortified Mach I
Mainboard	Asus P5WD2-E Premium
Memory	2 * OCZ DDR2 5400 EL GT XTC
Other	XFX 7800GTX Windows XP Pro SP2

I hoped you enjoyed this write-up, if you have any questions or comments please don’t hesitate to let me know at the forums.

If you live in Belgium, or are willing to pay freight costs (which can be quite high unfortunately), and you are interesting in having your phase-change cooling tuned/upgraded/refilled/fixed, please don’t hesitate to drop me a line and we’ll see what we can work out.