Reservoir and Pump Unit
The heart of the Koolance PC4-1025 liquid cooling system is the RP-1000 reservoir and pump unit, which also includes a controller and LED display in a 5.25′ bay unit. The latest version of the reservoir and pump unit (RP-1000 Rev.2, July ’06) features a manual pump speed control on the back panel.
- Pump Speed: Manual pump speed adjustment
- Power: DC power supplied from 4-pin Molex
- Fan: 3-pin connectors for radiator fans and optional case fans
- Temp: Three remote temperature sensors
- ATX: Pass-thru lead for computer shutdown feature
- Pump: Power to internal pump
- IN/OUT: Tubing connections
A clear plastic reservoir is built into the 5.25′ bay unit and fitted with a threaded fill port on top. The reservoir contains blue LEDs, which light up during operation and make it easy to check the coolant level as well as adding a KOOL look to the system. Unfortunately, the PC-V1000 does not utilize drive bay rails, which would make sliding the bay unit out to fill or top-off the reservoir a lot easier. As it is, you must remove two screws from both sides to free the bay unit and slide it forward.
The pump used in the PC4-1025 is the latest version of the Delphi DC pump (DDC) co-developed and marketed in
The DDC was specifically designed to provide high reliability, above average head and compatibility with systems incorporating 3/8′ ID tubing. The DDC operates on 12 VDC and is an inline pump, which means it is not designed to be submerged in a reservoir and must not be run dry.
You can read my review of the original Laing DDC pump here: DDC 12V Pump review
DDC – Key Features and Specifications
- Small footprint: 2.4 x 2.4 x 1.5′
- 50,000 hours MTBF (equivalent to 5 year lifetime)
- Convenient 12 VDC operation (ideal for PC applications)
- Superior real world performance (high pressure characteristics)
- Quiet operation (variable speed control)
- Maintenance free operation (when used with DI water and biocide)
- Operating voltage range: 9 to 13.2 VDC
- Nominal power (@ 12V): 18 W
- Nominal speed (@ 12V): 3,600 RPM
- Nominal head (@ 12V): 13′ (5.7 PSI)
- Nominal flow (@ 12V): ~108 GPH (>360 LPH)
- Connection size: 3/8′ OD barb (10mm)
- Maximum working pressure*: 22 PSI (1.5 Bar)
- Operating temperature range: Up to 140Â°F (60Â°C)
- Weight: 7.3 oz (207 g)
- Noise (quiet room): 30~32 dBA @ 2′
- Motor type: Electronically commutated, brushless DC, spherical
*Note: This is the maximum pressure the pump casing can withstand without damage if over pressurized from an external source. This is not the same as the discharge pressure (head pressure), which is approximately 5 PSI.
The Laing DDC pump uses a unique spherical rotor, which contains a small but very strong, two-pole permanent magnet encased in a stainless steel shell. The spherical rotor/impeller sits on top of a ceramic ball and is held in place and by the magnetic attraction between the rotor magnet and stator poles. The rotor/impeller is the only moving part in the pump and since there is no rotating motor shaft there is no shaft seal to potentially leak. The only seal used in the pump is a large O-ring that seals the end casing to the main pump body. The integral closed style impeller contains 9 curved blades, which are enclosed for greater pumping efficiency.
I measured the maximum discharge pressure (also referred to as shut-off head or deadhead) of the original DDC pump with a calibrated digital pressure gauge (accuracy Â± 0.04 PSI). At 5.4 PSI, it was slightly below the manufacturer’s nominal specification of 5.7 PSI (at 12 VDC) but well above most other pumps commonly used in PC water-cooling systems.
Another valuable piece of information regarding a pump’s performance is the relationship between backpressure and flow rate. The only time a pump will deliver its maximum rated flow is when there is zero backpressure or resistance to flow. Each component in a water-cooling system (waterblock, radiator, tubing, fittings, etc.) creates a certain amount of resistance to flow. This resistance results in a backpressure, which can be measured at every point in the system. During operation, the pump must overcome the total backpressure in the system to create flow.
The following P-Q curve was generated by measuring and plotting various pressure and flow rates for the DDC pump.
(click to enlarge)
As you can see the pump generates excellent head pressure even at moderate flow rates. This is particularly well suited to a 3/8′ system like the one used in the Koolance PC4-1025 with multiple waterblocks.
LED Display Panel and Controller
The Koolance PC4-1025 control panel is mounted into the front of the 5.25′ bay unit and consists of a 3-digit LED display and four push buttons. Three remote temperature sensors are included with the PC4-1025, which can be installed to monitor various temperatures inside the PC enclosure (CPU, GPU, internal air temp, etc).
The first digit of the LED display indicates which sensor channel (1, 2, or 3) is currently being displayed. The temperature readings can be set to display in either Â°C or Â°F.
By default, the PC4-1025 audio alarm will sound if any sensor reaches 55Â°C (131Â°F), the LED temperature will flash, and the fans will speed up to 100%. The alarm settings can be changed for all three sensor channels by the end user from 0Â°C (32Â°F) up to 99Â°C (210Â°F).
If the temperature value of sensor #1 (typically monitoring the CPU) reaches 3Â°C (5Â°F) above the alarm set point, the controller will automatically shut down the computer.