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Thread: variable speed pumps

  1. #21
    MCA
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    You either drop voltage, or change the frequency or both. The both seems to be what is done on the large pool pumps. For some reason the pool equipment folks are determined to hold onto AC motors, mostly likely due to low motor costs. The main alternative to using AC motors is to move to DC motors with permanent magnets. Changing the rpm of a DC motor is easier.

    Koi keepers in the States may see more DC motor pumps this coming year. Lets hope so. They are on the market in Europe. It is always good to have options.
    Koi keeping is not a belief system; it is applied science with a touch of artistry.

  2. #22
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    Yes, I could imagine DC pumps becoming the norm in the not so distant future.

    I'm seeing an increasing amount of DC components in appliances. Lots of DC fans, solenoids and actuators. Variable speed compressors are ever increasing. These are kinda neat as they use an inverter board to convert a standard line voltage of 120v to 240v! They can ramp it up and down according to needs. I find it amazing that they can do that. In the past these boards were known to fail, but in past few years they have become more reliable. Starting to see a lot of DC drive motors on clothes washers. Also drive systems using stator and rotor instead of direct drive.

    Indeed motor efficiencies have taken a leap in the past decade.

  3. #23
    MCA
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    I made sure my garage door opener was a DC direct drive. I did not want a a chain or belt to loosen and come off the track. The motor has an amazing about of torque.

  4. #24
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    Of course, dc motors! I haven’t worked on DC motors since the mid 60s. I was adjusting DC and AC motors for silent running on submarines. Back then they had commutators and brushes but I expect that has been improved. Very simple speed control by adjusting the DC current through the field (stator) winding!


    I don’t know whether they have a similar efficiency curve to our present pumps but we can find that out at manufacturers’ web sites. Don’t know what the efficiencies are either, will look into it.


    There’s no reason I am aware of for the single phase pump inverters, in the hobby, to be a consistent problem! The technology is old! If you know anyone replacing failed variable speed controllers, let me know how to contact them. If I can get into them, I may be able to get some idea of what’s causing the problems. I don’t have any ideas right now but new technologies (to the hobby) often have installer or operator problems, so we should keep an open mind here!



    The single phase sounds like a simple phase gated circuit, not unlike a lamp dimmer! I would expect commutation spikes to be a problem unless they are dealt with! Pumps built for VSC have grounded or shaft/bearing/stator isolation to eliminate the potential for arcing in the bearings. Also, the motor’s windings may see higher voltages or currents; VSC motors deal with that in the size and insulation of the stator windings. Does anyone know of these single phase voltage controls being operated on motors like ours?


    The FF pump looks like a well designed pump and the hobby needs a quality propeller pump. If I needed one and had discretionary (fun) money I would look at it’s potential to serve me in the task I wished to accomplish!

    I think the cost vs. the task doesn’t work for you! I’m not certain what flow you need! If you are simply moving warmer water through the pipes to avoid freezing or sulfur dioxide buildup as the weather warms again, a much lower flow pump would do fine.

    Considering the cost, I would look further!

  5. #25
    MCA
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    My Flowfriend pump is the best bit of kit I have seen for the hobby in many years. Very happy with mine.

  6. #26
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    Quote Originally Posted by MCA View Post
    My Flowfriend pump is the best bit of kit I have seen for the hobby in many years. Very happy with mine.
    Congratulations; It's no surprise you are excited with the physical design, Europeans are much more into hi tech reliable appliances. Here, in the US, we want the cheapest item in the catalog!

    Which is my approach!

    What you did get is access to a part of our technology that people on this board are very interested in. Since you will only need it for the winter season, you can use it in high turnover experiments in the active seasons!

    Talk to Kent Wallace; he may have some designs where airlifts fall a Little short.

    Now I'm jealous!

    I tried but didn't take the time needed to locate info on DC pumps! I did find info that shows brushless DC motors were just as efficient as the motors on our pumps! Does anyone have the name of European manufacturers providing DC pumps? I'll try Grundfos now!

  7. #27
    Oyagoi yerrag's Avatar
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    Quote Originally Posted by Rich L View Post
    Congratulations; It's no surprise you are excited with the physical design, Europeans are much more into hi tech reliable appliances. Here, in the US, we want the cheapest item in the catalog!

    Which is my approach!

    What you did get is access to a part of our technology that people on this board are very interested in. Since you will only need it for the winter season, you can use it in high turnover experiments in the active seasons!

    Talk to Kent Wallace; he may have some designs where airlifts fall a Little short.

    Now I'm jealous!

    I tried but didn't take the time needed to locate info on DC pumps! I did find info that shows brushless DC motors were just as efficient as the motors on our pumps! Does anyone have the name of European manufacturers providing DC pumps? I'll try Grundfos now!
    It sure is nice having a Flow Friend. You can tweak the flow rate to one that is optimized to your pond conditions. But it isn't for everybody. It costs a lot more. Not only that, I'm just wary of electronics that's not off-the-shelf. Think of our modern cars these days. You can't DIY it. You have to take it to the dealershio to get it fixed. And electronics, as high tech as it is, isn't known for longevity, even if it's German. Pumps last long if you don't abuse it. They're mechanical and give you countless years of operation. The less you cycle it, or turn it on and off (some people do to save power) the longer it lasts. Don't let it cavitate. Don't allow water to flow thru the impeller backwards. Etc..

    But if you already know the flow rates you need for winter and for the rest of the year, you could also install two pumps and you can run one for winter and another for the rest of the year. You can a y pipe where the flow going in can be from either of the two forks, each fork connected to one of the two pumps. This design also gives you redundancy, so that if one fails, the other could be used, if only temporarily.

  8. #28
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    Quote Originally Posted by yerrag View Post
    It sure is nice having a Flow Friend. You can tweak the flow rate to one that is optimized to your pond conditions. But it isn't for everybody. It costs a lot more. Not only that, I'm just wary of electronics that's not off-the-shelf. Think of our modern cars these days. You can't DIY it. You have to take it to the dealershio to get it fixed. And electronics, as high tech as it is, isn't known for longevity, even if it's German. Pumps last long if you don't abuse it. They're mechanical and give you countless years of operation. The less you cycle it, or turn it on and off (some people do to save power) the longer it lasts. Don't let it cavitate. Don't allow water to flow thru the impeller backwards. Etc..

    But if you already know the flow rates you need for winter and for the rest of the year, you could also install two pumps and you can run one for winter and another for the rest of the year. You can a y pipe where the flow going in can be from either of the two forks, each fork connected to one of the two pumps. This design also gives you redundancy, so that if one fails, the other could be used, if only temporarily.
    Quote Originally Posted by Appliance Guy View Post
    Great report.

    A couple questions- If there was significant heat on the controller, wouldn't that indicate phantom electrical usage? Seems to me that heat is energy, and wasted energy in this case. What other methods are there for controling rpm's other than dropping voltage??? I have little knowledge of the matter and you sound like you've researched this.
    Pump speed is determined by the # of poles in the driving motor and the frequency (60 cycles) that is supplied to the motor! VSC controllers simply change the frequency to change the speed.

    The VSC normally uses 60Hz to power it and changes the frequency to 400Hz to drive a 400Hz motor.

    When electronics fail consistently there's a problem in the design, installation or method of operation. Year's ago Sequence pumps were failing regularly. As it turns out the design engineers had done what they always do. They designed the pumps to be installed in systems designed by engineers! Our folks were trying to get as much water out of their pumps and were operating them at as low a head as they could, even lower then the pump was designed for. At a lower head than they were designed for, the pumps couldn't make it through a hot period at some locations. If you look on the motor, you will see a spec listed as SF, that's for 'service factor'! SF of one means a 1/4 hp pump is meant to be at it's maximum design flow and no more. Sequence swapped to motors with a SF of 1.25 and they stopped failing.

    So running pumps at full power with improper cooling were installation problems, not the pump's fault!

    Engineers select a pump that will operate at the 'best efficiency point' (BEP), which is at around 70% head.

    Anything that has an electrical current heats up! Mostly not enough to tell. But some components have enough voltage across them times enough current they generate heat, measured in watts. (EI=W{also called power! The components that generate the higher frequency have that condition voltage across them and current through them. They are normally mounted on heat sinks and are located to dump the heat to atmosphere.

    Ball valves are fine for regulating flow. Balanced aperture, valves are controlling the vortexes in the pipe for one reason or another that don't concern us.
    Knife valves only give support when the valve in fully closed and there is a support slot all the way around the knife and move's the knife entirely when fully open. When knife valves are partially open, the water velocity can bend the knife!

    Using valves to restrict flow consumes power. (Pressure times Flow = power) It's always better to lower flow with a device that doesn't need to develop head to slow the flow.

    VSP pumps have a best efficiency points too and the pump should be selected so the pressure/flow point falls near the pump's.

  9. #29
    Oyagoi yerrag's Avatar
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    When electronics fail consistently there's a problem in the design, installation or method of operation. Year's ago Sequence pumps were failing regularly. As it turns out the design engineers had done what they always do. They designed the pumps to be installed in systems designed by engineers! Our folks were trying to get as much water out of their pumps and were operating them at as low a head as they could, even lower then the pump was designed for. At a lower head than they were designed for, the pumps couldn't make it through a hot period at some locations. If you look on the motor, you will see a spec listed as SF, that's for 'service factor'! SF of one means a 1/4 hp pump is meant to be at it's maximum design flow and no more. Sequence swapped to motors with a SF of 1.25 and they stopped failing.
    That's very interesting Rich. That could only mean the people installing the pump weren't really looking at the pump curve chart, right? It would have told them that running at a lower head is a no-no. But of course, Sequence had to "upgrade" the motor because many engineers (if you still call them engineers) simply can't RTFM. And everyone else had to put up with a motor that costs more or uses up more power to accommodate the imperfect world. Which is one good reason pump manufacturers don't like to personally recommend pumps to users as users will just as easily mess up on designing and installing their pump systems and come around and blame the pump manufacturer for it. Pump dealers will just let you browse their pumps, and when you ask, provide you with literature, and let you decide which pump to use.

    Engineers select a pump that will operate at the 'best efficiency point' (BEP), which is at around 70% head.
    Thanks for sharing this. It's so hard to find charts that give you the BEP. Why is that?

    Rich, what exactly are VSC and VSP pumps? Would appreciate a bit of 101 on this topic.

    I'm not quite in agreement with using ball valves for regulating flow. Their use is more for on/off operation, as with gate valves. They can do the job, but not do it very well. Eventually, they will not fully close because some deposits/sediments block the closure. And with ball valves, they can't regulate in small increments. But they will do for the time being. I read about globe and diaphragm valves doing flow regulation well, but they are hard to find and they must cost a lot. I saw wye valves on flexpvc.com. They're pricey:

    Product Listing PVC-Valves-Wye-Pattern

    I can understand why we end up settling with ball valves.

  10. #30
    MCA
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    Exactly. I have my at 1800rpm for the summer. Come fall I will likely drop to 1600rpm and maybe something like 1400rpm for the winter. I will also put an insulated tarp over the shower during the winter.

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