Alphacool ST30 X-Flow 360mm Radiator Review

Technical Details and Features as listed by Alphacool

Technical specifications:
Material internal: Mostly copper
Material casing: Side panels steel, threads brass, copper chambers
Colour: Black
Dimensions (LxWxH): 413 x 124 x 30mm
Radiator size: 3x120mm
Connection threads: 4×1/4“
Mounting thread size: M3
Pressure tested: 1.5bar
Weight: 686g

The following Technical Drawing is provided courtesy of Alphacool.

Dimensions Measured on the Radiator Tested:

Radiator Core Dimensions:

Our review sample measurements were virtually identical to those listed by Alphacool.

The 16mm thick core arrangement consists of single, finely louvered fins with a 15 FPI count between a single layer of twelve x 1.9mm thick tubes. The tubes are arranged in a single pass (X-Flow) configuration. This means that the coolant enters the radiator at one end, divides evenly to travel through all the tubes simultaneously in a single pass before exiting at the other end.

It is unlikely this thin, medium density core will produce outstanding performance results, it is a slim radiator after all, but we think ST30 X-Flow should do well with medium speed fans.

The 15 FPI count seems a good match for the core thickness and the fins were very evenly spread between the tubes on our review sample. We note here that the 15 FPI of the review sample is very slightly less than the 16 FPI stated in the specifications.

X-Flow radiators are usually less restrictive than their single layer dual-pass counterparts, but sometimes tube thickness is adjusted to keep the flow turbulent through the radiator. We’ll just have to wait until we get this sample on the bench to see how restrictive the ST30 X-Flow actually is.

Finish and Features

With the current revision of NexXxos radiators (blue logos), Alphacool really have stepped up on the quality control. The satin black finish on our review sample was flawless and external joints all look to be well done.I am admittedly a fan of a matte black finish on radiators, but the deep black, satin finish of the ST30 X-Flow really impressed.

Company logos in conspicuous places is not something we favor, especially when they are placed so that there is a 50/50 chance that the logo will be upside down when the component is installed.

The ST30 X-Flow has the “acool” logo painted / printed on both side panels and being blue, it really stands out. Depending on your installation orientation the logo may end being upside down.

The ST30 end tanks are identical, but are installed with the ports on opposite sides at each end. The main (if not only) advantage of a X-Flow radiator is the ability in many installation scenarios to make tubing runs shorter which almost always equates to a neater looking system. This in our opinion is the ST30 X-Flow’s main draw while also taking up very little space (thickness only 30mm).

The tapered shape of the end tanks will greatly assist to eliminate dead flow spots and avoid trapped air pockets.

Each end tank is fitted with 2 x G1/4 ports which are opposite each other on the tank.

We think multi-port rads are the awesome, so we’re happy to see the The ST-30 X-Flow has not missed out on this feature. The extra ports can be used for a drain tap or temperature sensors and is often the easiest way to fill or bleed a loop when roof or floor mounted.

Note that when mounting the radiator directly to the chassis (no fan in between) some case modding may be required to accommodate the stop plug or other fitting which protrude past the radiator mounting points.

One thing we constantly complain about on Alphacool radiators is that the port threads are painted.

We see no valid reason for painting the threads and in fact makes it more likely that the end user will introduce paint chips into the system when installing their fittings.

If you have a G1/4 tap, you might as well run it through the threads and clean out before flushing as I usually do.

Alphacool’s deep black fittings are a perfect match to the ST30 X-Flow finish.

Shiny Nickel fittings look pretty good too!

The large 26mm OD Bitspower 1/2 x 3/4 compression fittings probably wouldn’t fit if the G1/4 port was installed straight on our review sample. We guesstimate that a 24mm OD fitting would be the maximum size compatible with the ST30 X-Flow.

Screw protection plates are fitted under the M3 threaded mounting holes. Protection Plates are a feature we wish all manufacturers would incorporate. Even though screws are provided that can not puncture the core (short threads & thick shanks), Alphacool continue to provide the extra insurance by installing plates on all of the NexXxos series radiators.

We are glad the ST30 has the protection plates as a back-stop because the outside tubes are located directly under the screw holes.

The inbuilt shroud depth is ~7mm to the fins (~6mm to protection plates) on both faces of the ST30 X-Flow.

When a standard 25mm thick fan is fitted using the supplied 30mm length screws, the bottom of the screws are still well clear (~2mm) of the protection plates.

The 15mm fan spacing is perfect.

As we have seen a few of radiators with poorly located fan mounting holes, we also take these measurements to check that specs are being adhered to during manufacturing.

105mm spacing for the fan mounts were perfect also, both length-ways and across the ST30 X-Flow.

Given all the fan hole measurements were good, we had no dramas attaching 120mm fans to the ST30 X-Flow.

The ST30 X-Flow is a slim 360mm radiator with a single pass, X-Flow coolant path and has 2 ports on each end tank. The medium density fin array between reasonably thick 1.9mm tubes should equate to very low restriction levels and we expect it to perform quite well with medium speed fans. The tank design is good and overall the radiator feels solidly built. The paint finish and build quality is great, however painting the port threads is a practice which annoys us. So far so good.

Let’s see how it performs…