We have seen many people mentioning that they had PWM fan controllers, and that they were planning to use it to control the speed of our PWM compatible pumps. There is a potential issue with this, which needs clarification as follows. The issue essentially comes from a confusing naming convention of the various fan controllers.
Having what’s called a PWM speed controller does not mean that you will be able to control our pump. There is an excellent reference article written by Dave at overclockers.com that explains how PWM works.
Excerpt from the article:
There are PWM controllers and there are PWM fans, but the way in which PWM is implemented in each differs greatly: a standard PWM controller modulates the 12 V supply line of an “ordinary” 12 VDC motor. Conversely a PWM controller for PWM fans – such as the one featured in this article – doesn’t modulate the 12V supply line but instead sends a PWM signal along a different supply line (the magic “fourth wire”) to a more advanced 12 VDC motor, leaving the 12 V supply line uninterrupted. Designated PWM fans not only have internal circuitry which differs from that of standard fans, but because they are designed with speed control in mind the motors themselves are usually more advanced (and expensive). So, PWM speed control of a standard fan is indeed very different from PWM speed control of a PWM fan… Nidec even goes so far as to say that modulating the main supply voltage is not advisable:
Pulse-width modulation of DC operating voltage to modify fan speed [edit: in PWM devices] is not recommended. Transients generated by that approach can irreversibly damage motor commutation and control electronics and dramatically shorten the life of a fan.
End of excerpt.
As we can see above, it is critically important to distinguish between PWM fan controllers designed to manage regular 3 pin fan, and PWM fan controllers specifically designed to manage 4 pin PWM fans. In the first type, the 12v supply line is modulated by the fan controller and in the second type the controller sends a signal thru the 4th wire to the fan, and the fan motor modulates its speed according to this signal by using its onboard controller.
What is important to understand above is that PWM fans, and the Swiftech PWM pump, are designed to receive a fixed 12 v supply. While the voltage may vary somewhat, the range is usually limited; we’ll publish the safe operating range for our pump upon release.
Therefore, if you have a PWM fan controllers it does not necessarily mean that you will be able to control our pump. You need to make sure first that your controller is designed to manage 4-pin PWM devices.
Lets’ look at some examples and head over to Frozen CPU to look at some of the available PWM fan controllers:
The key word above is 3-pin. This controller may use the motherboard PWM signal to manage the fans, but it still manages them thru voltage modulation, therefore this would not work for our pump.
Status: Not compatible
Sunbeam 30W Rheosmart 3 Channel Smart Fan Controller - Black (PL-RS-3)
Status: Not compatible
Sunbeam 30W Rheosmart 6 Channel Smart Fan Controller - Black (PL-RS-6)
Status: Not compatible
Zalman PWM Mate - Automatic / Manual PWM Fan Controller - Black
Status: Compatible, not validated
Zalman ZM-MFC1 Combo 5-Channel PWM / 3-Pin Fan Controller - Black
Status: Pending validation
Zalman ZM-MFC3 Multi-Fan Speed Controller / Temp Monitor
Status: Compatible, validated as below:
Pump min= 1500rpm max=3000rpm
Helix PWM fans min= 1120rpm max=1800rpm