...are closed loops becoming obsolete?

gcarroll

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All of a sudden I hear crickets in the calm..
Where did Jabao come from and why the company bashing?
Because if you leave out the companies that pull flow numbers out of their tail, then reality sets in.
 

gcarroll

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Do I have to break out my "kill a watt" to prove consumption ?
Also ac to dc power supplies are solid state and has minimal loss in the conversion.
It only took 100 posts to start questioning ac and dc when this was already battled in the late 1800's
Consumption means nothing if the flow is not as stated.
 
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143MPCo

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Efficiency in a pump would be conversion of electricity to torque. You cannot beat the efficiency of a fixed speed ac induction motor any other piece you add to the chain reduced efficiency. Any component added will use power which is less power to pump with. A fixed speed ac pump may not fit the application but there is no more efficiency to gain because you cannot further reduce the system.

Better yet here is the math
http://www.mcnallyinstitute.com/06-html/6-01.html

ok fine... but, how would you argue the power consumptions of AC to DC pump being better or worse?

No one has direct dc service to their home. That voltage must be converted the hysteresis of this step down and rectification takes energy. This is loss and it is one in most situations you are paying for. Let’s say you run on solar or a battery so no conversion no loss. Higher voltages are the first factor in mitigating loss Power = V·I and Loss = I2R. So you would need an output of 110 or 230 to have the same potential in a dc system. That’s one heck of a battery. Should I keep going?

More math
http://www.me.ua.edu/me416/LECTURE MATERIALS/MotorEffic&PF-CM5.pdf

one last thing: Consumption I.E. kilowatt hours is different than efficiency i.e. killo watts/ torque.

trying to find a balance between the two and still maintain adequate flow requirements will impact the bottom line, question is how much are you willing to pay for it!?!?
 

twilliard

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Anyone can get this 1446487194982-1035735401.jpg

To determine where your money is most spent.
 

gcarroll

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But we are talking efficiency in this thread regardless of flow ;)
Efficiency or current draw. IMO they are completely different. To calculate efficiency without the known flow seems just a little shady IMO.
Anyone can get this 1446487194982-1035735401.jpg

To determine where your money is most spent.
Had one for over 10 years. Being from California, it is a must to know where you electricity is going. Most reefers around have ditched this method as it can also be monitored with their Apex.
 

twilliard

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Efficiency or current draw. IMO they are completely different. To calculate efficiency without the known flow seems just a little shady IMO.
Had one for over 10 years. Being from California, it is a must to know where you electricity is going. Most reefers around have ditched this method as it can also be monitored with their Apex.
Most people don't run an apex so this is a vital tool to know where your kwh's are spent.
And the biggest consumer of any tank...

Heating
Inductive heating is the biggest energy waster. AC coil or carbons.
An ac coil will produce more heat than a PWM dc coil.
 

gcarroll

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Heating
Inductive heating is the biggest energy waster. AC coil or carbons.
An ac coil will produce more heat than a PWM dc coil.
Please explain this. I want to make sure I understand where you are going with this. IMO, you are starting to flirt with the laws of thermodynamics

BTW, we are totally off topic now as this has nothing to do with closed loops. The only reason DC pump questioning was that the OP failed to differentiate the form of DC pumps he was talking about.


As for the Apex, I meant to say around here the Apex is commonplace.
 

twilliard

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Now lets talk longevity
Most ALL aquarium pumps or powerheads use a ceramic shaft with ceramic bushings.
Lets not compare apples to oranges here.
Lets start with internal pumps and powerheads
No matter the currents applied (ac or dc) we will see failure
This is simply due the methods employed at stabilizing the rotor.
Its called wear
Now if we were to compare this to an ac driven external pump that employs bearings it will run till the tank comes down. But at what cost due to PE?

So who is your winner? Thomas Edison or nikola Tesla?
 

twilliard

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Please explain this. I want to make sure I understand where you are going with this. IMO, you are starting to flirt with the laws of thermodynamics

BTW, we are totally off topic now as this has nothing to do with closed loops. The only reason DC pump questioning was that the OP failed to differentiate the form of DC pumps he was talking about.


As for the Apex, I meant to say around here the Apex is commonplace.
Isn't thermal dynamics part of energy loss?
So no not off topic :)
 

gcarroll

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"DC pumps also tend to be more efficient. However, AC pumps usually are designed for higher speeds and larger bursts of power. They also have a longer working lifespan than DC pumps."
Hopefully 143MPCo understands this clarification. As I said earlier, I had a problem with this statement.
Now lets talk longevity
Most ALL aquarium pumps or powerheads use a ceramic shaft with ceramic bushings.
Lets not compare apples to oranges here.
Lets start with internal pumps and powerheads
No matter the currents applied (ac or dc) we will see failure
This is simply due the methods employed at stabilizing the rotor.
Its called wear
 

gcarroll

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"DC pumps also tend to be more efficient. However, AC pumps usually are designed for higher speeds and larger bursts of power. They also have a longer working lifespan than DC pumps."
The laws of thermodynamics dictate that all of the energy going into the motor is all converted to heat.
 

twilliard

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The laws of thermodynamics dictate that all of the energy going into the motor is all converted to heat.
Hey Greg not here to argue.
We all have valid points.
But still DC will rule one day when it comes to pumps and efficiently pumping or moving water.
 

gcarroll

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But still DC will rule one day when it comes to pumps and efficiently pumping or moving water.
Maybe, Maybe not.

Wouldn't using a VFD to control an AC pump possibly be more efficient? I know there are companies doing this in our industry.
 

ksed

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Please stay on topic. You are all over the place. I listed a pump that runs on 120v which is approx. 10% more efficient than the 12 v DC. In this case the AC pump is more efficient than the DC regardless which one produces more heat. There are many more factors that play in the efficiency of a pump than thermodynamics. This was discussed on post 120


But we are talking efficiency in this thread regardless of flow ;)

Most people don't run an apex so this is a vital tool to know where your kwh's are spent.
And the biggest consumer of any tank...

Heating
Inductive heating is the biggest energy waster. AC coil or carbons.
An ac coil will produce more heat than a PWM dc coil.

Now lets talk longevity
Most ALL aquarium pumps or powerheads use a ceramic shaft with ceramic bushings.
Lets not compare apples to oranges here.
Lets start with internal pumps and powerheads
No matter the currents applied (ac or dc) we will see failure
This is simply due the methods employed at stabilizing the rotor.
Its called wear
Now if we were to compare this to an ac driven external pump that employs bearings it will run till the tank comes down. But at what cost due to PE?

So who is your winner? Thomas Edison or nikola Tesla?
 

ksed

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I wish you would refrain from posting misleading information. Read post 120.
The link provided on post 108 provides you with the information in regards to what a DC pump is. I suppose you did not read it. I highly recommend that you take some time and read it as your current posts have no validity.
Hey Greg not here to argue.
We all have valid points.
But still DC will rule one day when it comes to pumps and efficiently pumping or moving water.
 
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VFD...

http://www.cyclestopvalves.com/vfd-energy_8.html

Most of the articles I have read that claim energy savings when using a VFD control are misleading. If you carefully read these articles you will find that other parameters were changed at the same time as the VFD was installed. Usually the head required was reduced by increasing the pipe size or increasing the NPSHA, the use of a dump valve was discontinued, or a smaller or more efficient pump was installed. Then a VFD is added to the control system and given the full credit for the reduction in energy when it is simply not the case. Other articles have used the Affinity Law to show energy is being saved by the cube of the RPM. However, they neglect to mention that head is lost by the square of the RPM. This limits the minimum RPM possible that will still produce the head required. These articles falsely show incredible reductions in power that go along with reducing the RPM by 50% or more. When in reality the RPM can be reduced by no more than 10% or the head required is no longer attainable. According to the Affinity Law a 10% reduction in RPM produces only a 23% reduction in power consumed, not the 50% or 90% reduction in power that many drive manufacturers would like for you to believe. Only those who lack understanding of how centrifugal pumps really work would claim VFD's save energy.
 

gcarroll

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Other articles have used the Affinity Law to show energy is being saved by the cube of the RPM. However, they neglect to mention that head is lost by the square of the RPM. This limits the minimum RPM possible that will still produce the head required. These articles falsely show incredible reductions in power that go along with reducing the RPM by 50% or more. When in reality the RPM can be reduced by no more than 10% or the head required is no longer attainable. According to the Affinity Law a 10% reduction in RPM produces only a 23% reduction in power consumed, not the 50% or 90% reduction in power that many drive manufacturers would like for you to believe. Only those who lack understanding of how centrifugal pumps really work would claim VFD's save energy.
We are discussing a low/minimal head application here are we not? Sounds like the stuff you are referring to are high head applications.
 

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