Fluid O Tech TMFR pump wiring issue

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#1: Post by EthanL »


I recently acquired a TMFR pump from ebay, it came without the original controller, and I have a VFD to pair it with. The problem is I don't know which wire goes to which port.


There are four wires coming out from the pump motor, the yellow+ green one is the ground wire I know, and there are one blue, one pink and one brown/dark wires. Which should be connected to the U, V, W ports on the VFD?

Thanks in advance for any advice!

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#2: Post by Chert »

For this ignorant one who doesn't wish to google just now, can you please define 'TMFR' and 'VFD'?

LMWDP #198

now more than ever


#3: Post by EthanL »

Hi Flint,

The TMFR is just a name that Fluid O Tech gave to this pump model, VFD does stand for Variable Frequency Drive.

The motor on this pump is a three-phase one, so is in need of an inverter. The original pack includes a fluid o tech controller, basically converting ~110 VAC to 90V three phase for the pump motor. A VFD does the same thing.

TMFR pump has an advantage over normal single phase pump motor is that it allows to adjust the rotation speed of pump to a certain degree, and this is the part I'm interested and currently looking into.

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#4: Post by AssafL »

If it is a three phase motor (synchronous or asynchronous) the 3 phases matter not which way they are wired. If it rotates in the other direction (check with pump disconnected) flip 2 of the 3 wires.

The speed will depend on the number of poles in the motor and the frequency of the drive.
Scraping away (slowly) at the tyranny of biases and dogma.


#5: Post by EthanL » replying to AssafL »

Will running the opposite direction do damage to the pump? Not sure whether synchronous or not...

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#6: Post by AssafL »

I am not sure. Running it dry won't do it good. I think rotating it backwards with water will push against one way valves. Etc.
Scraping away (slowly) at the tyranny of biases and dogma.

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#7: Post by Peppersass »

You might try PMing H-B member shadowfax. About 10 years ago he retrofitted a TMFR pump into a GS/3 for pressure profiling. He may have a diagram or may remember the wiring.

Lots of information on his TMFR project and other attempts using gear pumps in this thread. I quickly scanned it and didn't see a wiring diagram, but it could be in one of the links.

I'm sure you've found the manual, but if not it's here.

Personally, I went with a Fluid-O-Tech gear pump for my GS/3. Much simpler to control and no issues with the bypass valve.


#8: Post by EthanL » replying to Peppersass »

Thanks Dick for all the info, that thread is the most exhaust on the net about this pump, and it went from rotary pump to gear pump eventually for better electronic control.

I remember the Vesuvius has a gear pump as well if correct, is gear pump better in regard of electronic control? If I want to control the pump on the fly(more like a mechanical control), with a TMFR pump, that might be easier, with help from a VFD and potentiometer. I may take the risk and run a trial with a guess of the wiring, with minimum power input, and switch to the right wiring if the pump runs ccw.

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#9: Post by Peppersass »

Having no personal experience with the TMFR, I can't say that electronic control of a gear pump is better, per se, but I believe it's simpler in terms of components required. For manual profiling, all you need is the gear pump, a 24 VDC power supply, a couple of resistors and a potentiometer. I got a little fancier and substituted a voltage regulator for the resistor divider and a touch-sensitive knob for the pot. Later I added an Arduino, pressure transducer and interface to the machine's electronics for more automation.

The concern I have with the TMFR is what shadowfax found with the bypass valve. Don't have that problem with the gear pump. In fact, my gear pump doesn't have a bypass valve.


#10: Post by EthanL »

Went through that thread again, gear pump is quieter and doesn't need a bypass valve compared to 3 phase rotary pump.

I will continue with what I have at the moment, get the rotary pump running and output pressure controlled. The bypass valve can be added along the flow path, without drilling the giclur, as Andy mentioned in that thread.

Currently I'm living with a Breville dual boiler, and I don't see I will put a rotary pump on it, as I'm quite happy with stock performance. It will be interesting to see how a controllable rotary pump works on a SBDU machine, or in best case an espresso-only machine. Many thanks for the help from everyone!