Koolance CTR-SPD24 10-24 Volt Speed Controller

Posted: February 28, 2011 in Control-Monitor, Fans, Pumps
Tags: , , , , , , ,

The Koolance CTR-SPD24 is a new 24 Volt speed controller which will take your ordinary 12V power supply and allow you feed and control a pump or fan from 10 volts to 24 Volts.  This is really exciting because previous to this, 24V or higher voltage was typically only possible with a separate dedicated power supply.  In addition, the controller is ideal in controller the new stronger PMP-450S pumps.  So unlike your typical fan controller which is either PWM or resistance based (Can only reduce voltage), this one can got both directions.

Before going too far, I would like to thank Tim from Koolance.com for supplying two of these units that I have been using for my PMP-450S performance and noise testing.  Thanks!


Here are some pictures showing the box, packaging, and size of the controller:


Minimum and maximum voltage settings

For testing I am including both the minimum and maximum photos of the PMP-450S pump under load using the controller.  I fed the controller precisely 12.0V using my test power supply, and then measure the pump voltage at the pump plug for the actual voltage provided.

Minimum Voltage = 10.14V (Note: I would suggest 11V as the minimum for the PMP-450S)

Maximum Voltage (Note: I would suggest 20V as the PMP-450S maximum)


To determine the efficiency of the controller I measure the amperage and voltage fed to the combined pump plus controller, then did the same for just the pump.  Using these two sets of data I was able to determine the energy lost through the controller.  Here are those results:

Efficiency Calculation

It turns out the controller is very efficient at over 89%, so the heat-sink and controller is wasting up to about 5 watts at a 48 watt consumption level.  I did also measure the heat-sink with a laser thermometer and it does get warm/hot to the touch.  I measured roughly 45C in a 25C ambient which is warm, but not that hot.  I have actually measured some pumps measuring upwards of 60C, so 45C seems to be relatively good.

What good is 24V you might ask?

It’s what the “STRONG” or PMP-450S NEEDS for full out pumping performance.  The PMP-450S with this controller will easily outperform the most powerfull PMP-450/DDC pump.  It also serves as a “Vario” feature for the PMP-450S because that pump does not come with a variable speed knob.  Basically, the PMP450S and this speed controller should go as a pair for full pump performance.  Here is how the “STRONG” compares to the PMP-400 with top, and I haven’t even completed testing with a top on it.  It is simply one of the most powerful pumps you can buy at that price point.

24Volts gives the PMP-450S it's "STRONG" performance

I also know of a few people that have 24V fans and there are other needs I’m sure.  I would not suggest the controller for the regular PMP-450 pump though as the performance gain on that pump model is fairly minimal.  The pump that needs this is the PMP-450S, she likes the extra volts!!..

I really like this controller, particularly for it’s compact size, simple analog control, and extra legs it gives to the PMP-450S model pumps.  I could see this controller also coming in handy for other 24V needs, no more need to have a  separate dedicated power supply for high voltage, this fits that need nicely at a good price.  I really could not find any faults in this controller, it’s a nice compact unit and has plenty of power for one PMP-450S.  It would even have enough power to feed two PMP-450S pumps at lower voltages/lower flow rates.  I will be using these for a variety of 24V testing needs in the future, extremely nice!!

 Update 7/27/11 Connector Photo

This is how you connect up a molex connector type pump like the PMP-450S:


    • Ralph says:

      Martin can I use this controller for Koolance PMP-500 pump? I like this smaller controller than the recommended controller for the Koolance pump.

      • Martinm210 says:

        No, 500 is not designed for more than 12v and that controller only goes down to 10v. Feeding it 24v could damage the pump so You really want the spd10 or other 12v and under type controller.

  1. al360ex says:


    I am planning on buying two PMP-450s with 2 CTR-SPD24 controllers. However, I would like to if it is possible to control these two things with a fan controller ?

    Here is what I had in mind :
    12v from PSU ->Fan controller power input->CTR-SPD24 conected to the FC 3-pin output->24v to PMP-450s
    I would use 1 channel per pump. There would be only a single loop, with the 2 pumps in a serial connection.

    Now, my questions :
    #1 Would this setup work ?
    #2 Do you know how many RPMs the fan controller should indicate if running this at 12v ?
    #3 If I keep the knob of the CTR-SPD24 at the maximum, but use my FC to feed it only 6v, would the pump receive 12v ? What I mean is if this is a linear curve, or if it is exponential.
    #4 Could I run the two pumps at different voltages, or would it make everything explode ? 🙂

    Thanks, and great website !

    • Martinm210 says:

      #1,#2, I’ll have to do more testing to see if you can do what you’re asking as I never really thought about that sort of setup and simply fed the controller 12V.

      #3, Not sure about the first part, but you can see the RPM levels in my strong testing here:

      It varies depending on how restrictive the loop is, rpm reduces as restriction reduces.
      #4, Yes, I have yet to see how that could hurt anything if they are both the same pump. Each pump simply adds more differential pressure. You might want to take some extra care with the hose clamps though, these pumps are really strong.

      Hope that helps some. I’ll see if I can squeeze in some additional testing to check on the questions I couldn’t answer.

    • Martinm210 says:

      FYI, I just checked that idea you had and unfortunately varying voltage to the controller does not work. It pretty much holds voltage constant regardless of the supplied voltage until you reach a certain limit (around 9V) where it starts to shut down.

      I guess that’s good for maintaining a constant voltage, but you won’t be able to use another fan controller to feed the control unit. Besides, there is probably not much on the market that could feed 50 Watts in a single channel anyhow.

      • the finisher says:

        Martin, he wants to feed 2 controllers and 2 pumps from 1 fan controller channel +100 watts= blown fan controller for sure!

        I now have the 3-140L 24v fans on one of these gems, works great! Thanks for the test:D

      • Martinm210 says:

        Good point!

        Glad it’s working well for the 140Ls..:)

  2. the finisher says:

    Oops, only one pump per channel, still sounds like a “no way” to me.

  3. Wes Shull says:

    I just purchased the CTR-SPD24X2 controller for my 452X setup (twin 450 pumps). Works solid but I cannot tell if I’m getting more than 12V per side…I have the RPM sensor hooked to my TMS200 board and that only reports 12V/about 4800rpm. I do have a very restrictive loop and with both pumps in serial I’m getting slightly more than 1GPM. What’s interesting is if I move the speed controllers back and forth a bit I get these instant speed-ups (can see my flow meter spin up) but everything settles back down in a few seconds. Would be nice to see you review the product…maybe I have it setup wrong.

    • Martinm210 says:

      I’m guessing you have 450 pumps and not 450S pumps?

      PMP450 pump can operate at 24V, but the RPM will dial itself back down to the same as 12V. You can see the performance difference here between 12 and 24V on the PMP450:

      There is only some very minor RPM increases at very low restriction levels and in general…the PMP450 doesn’t gain much of anything with higher voltage. The PMP450S or Strong is the pump model that gains from higher voltage, but I wouldn’t recommend using aftermarket tops on that one. With 24V it will see upwards of 5900RPM which can cause vibration problems with aftermarket tops.

      Anyhow, I’m guessing you are feeding the pumps 24V (Could be checked with a multimeter in DCV), but you are running PMP450 pumps which don’t really get any benefit from doing that. Sorry, but the 450″S” or strong model is the one that gains from voltage.

      • Wes Shull says:

        Well…there you go. I did get a 12-13% bump from .88 to 1.04GPM so it was worth it…if I decide to buy a few 450S pumps in the future I’ll be ready for it. Might remove the RAM cooler…that’s really just for show…should get a nice bump up there as well.

  4. Hey Martin, I was just wondering, have you tested the CTR-SPD24X2 controller at all? I picked one up like Wes, but I’ve got the 450S pumps, and I ran into a MAJOR problem when the controller almost caught fire. It might be simple human error, but what’s the proper connection method for a pump controller like this one in the review, or the CTR-SPD24X2? I can’t seem to find a diagram anywhere online, and I just went with a general assumption based on how the cables were set up.

    • Martinm210 says:

      No, I have not tested the newer X2, only the ones I’ve posted here. You do need to be very careful that it’s hooked up right.

      The female 4 pin molex on the PCB = PSU input power
      The male 3 pin header on the PCB = output power

      The adapter cable is meant to be used on the output power connector so you can feed a 4pin pump such as the 450S. You do not want to connect your PSU to this and accidentally feed power the wrong way. I guess I never thought of doing that because I started with the other controller and didn’t need the adapter for feeding the PMP-400 pump which has a female 3 pin connector, but I can see how it’s possible to mix that up now.

      I’ll see about adding a diagram of sorts to help with this.

    • Martinm210 says:

      FYI, added a connection type photo that should explain the setup pretty well.