Watercool HTSF2 3×120 LT 360 Radiator Review

Technical specifications as listed by Watercool:

• Material heat exchanger: Copper (tubes), aluminium (fins)
• Material corpus: powder-coated Steel (black), Stainless steel
• Dimensions (L x W x H): 410 x 130 x 50 mm
• Weight: approx. 1550 g
• Pressure tested: 5 bar
• Threads: 2x G 1/4” (DIN ISO 228-1)

Dimensions Measured on the radiator tested (retail unit):

Radiator Core Dimensions:

At 50mm thick The HTSF2 classifies as a medium thick (35mm – 52mm) rad in the round-up.

The fluid volume was unable to be measured due the to flow path of the tubes.

It has low density core of just 10 FPI. The fins are aluminium but the tubes are copper which have been painted silver to match the fins.

The HTSF2 is the only finned tube style core in group 1 of the round up. The core consists of 3 parallel tubes that run back and forth across the radiator six times. In case that wasn’t clear I decided to dismantle the HTSF2. The ability to dismantle makes the HTSF2 a modder friendly rad, by being able to remove the panels for painting if black is not your thing.

In my tube count I listed 6 – which is the tube count across the face of the core. But the finned tube style core is so much different that it requires further explanation. The tube configuration is actually made up of 3 rows of 3 U shaped copper tubes, effectively creating 18 tubes. These are then soldered together on the port end to create 3 total tubes that join at the ports.  These pictures might help to imagine this:

The non port end is not soldered because these are pieces of copper tube that have been bent on this side.  The port end on the other hand gets the soldered joints:
Now you can start to piece together how it works.  Each of the G ¼ ports has a small “splitter” tube right behind it. So when coolant enters the rad it is immediately split into thirds for it’s journey through the core. As the coolant is traveling through the 3 different flow paths simultaneously, it is known as parallel flow.

So if we again look at the face of the rad we can follow the front “tubes” flow path as it travels right and left six times (Hex Pass) until it exist the outlet port. Now picture the 2 other “tubes” behind it with coolant flowing in the same pattern simultaneously and we have the complete picture of the flow path. Technically we could call this a Parallel Triple Tube, Hex Pass Finned Tube Core, but that might confuse people.

With all those 90° bends, 15 in total, I’m expecting this to be quite a restrictive radiator even though those bends are in parallel. Watercool advise otherwise with this statement “The triple parallel layout of the HTSF2 ensures a low flow-resistance”. I found this hard to believe particularly given the reputation of the Mo-Ra radiators but my restriction testing will provide the answer.

Finish and Features

Watercool have chosen to use stainless steel for the housing enclosure panels. The side panels are powder coated in black for a smooth and durable finish. The two end pieces are mirror polished with the non-port end piece having the model laser engraved for a stylish finishing touch.

The whole unit feels solid despite have only 8 pop-rivets joining the panels to the core. Of the 15 rads in group 1 this is the rad which has the best finish and most appealing style. Hopefully it will perform as well as it looks.

Two things did annoy me though, and both had to do with the brass ports. The brass ports had not been joined to the copper tubing squarely, resulting in the ports sticking out at a weird angle. I did manage to bend them straight with some brute force, but at was done with the risk of weakening the solder joints or worse, breaking the joint.

The other disappointment was how far out the brass G1/4 ports protruded from the radiator housing:

There are just the 2 ports on the HTSF2 III, inlet and outlet. There are no alternative port options or a bleeder/fill port on the return tank. This is of course due to the hex pass nature of the design.

Let’s see how it performs…