Difference in DC pumps vs. regular pumps

marvelousone · Jan 19, 2018

What is the difference between the two in reference to pro and cons. Why go with or the other. Does one put off less heat. Use less voltage?

nkyreef · Jan 19, 2018

One of the biggest pros for me is the programmability. Using my Apex I can adjust the speeds to what I want without closing valves or using any other restrictions. When I feed I have the pump turned down so that it keeps positive pressure on the return line without turning water over. This prevents any back siphon to the sump. I also have a profile setup that matches a separate pump I use when refilling the tank during water changes. I never thought it was a big deal that I couldn't control the speed of the pump until I installed one.

mjlash22 · Jan 20, 2018

DC
Pros: controllable, more quiet than AC
Cons: shorter life (personal experience)

AC
Pros: more reliable/longer life (personal experience)
Cons: not controllable (some offer manual control ability)

redfishbluefish · Jan 20, 2018

My return pump originally was a MAG 9.5. I switched to a Waveline DC6000.

Here's the differences I noted:

Power Consumption
MAG 93 W. Produces fair amount of heat.
Waveline 48 W (at 100%, I run at approximately half speed)

Controllability
MAG - need valve on exit port
Waveline - 11 speeds

Waveline also has a feed mode and has slow start-up. I don't use this, but it's also Apex controllable.

marvelousone · Jan 20, 2018

Is the pressure drop different between the two. EX. 6foot pipe the pressure drop is the same.

Ranjib · Jan 20, 2018

In terms of circuitry, I doubt there is any difference. From my limited understand, all pumps work in DC. All AC pumps uses a transformer and rectifier to convert the AC into DC. In DC pumps, this circuitry is outside, i.e. the rectifier is external. This directly impacts the heat generation, and due to flexibility (of keeping the AC-> DC conversion circuit outside) one can optimize it easily for better performance /efficiency. This also allows the regulation.

Which means, you can of course hack an AC pump to be controllable :0) . But it will loose its structural integrity. DC pumps on the other hand are new, at least in the segment we are interested. Hence it will take some time for them to become as reliable as the AC pumps. But they will almost always take less energy and offer more controllability (and be expensive)

Not very related to the topic, but just an FYI , that most of our consumer electronics is DC based. Its due to some historical events (and very little engineering reasons) that we run electrical grids in AC. This whole thing is not super logical or efficient. Put other way, future home might have DC supply straight. and the consumer electronics dont have to ship their individual transformers and rectifiers

recess62 · Jan 20, 2018

Ranjib said:
In terms of circuitry, I doubt there is any difference. From my limited understand, all pumps work in DC. All AC pumps uses a transformer and rectifier to convert the AC into DC. In DC pumps, this circuitry is outside, i.e. the rectifier is external. This directly impacts the heat generation, and due to flexibility (of keeping the AC-> DC conversion circuit outside) one can optimize it easily for better performance /efficiency. This also allows the regulation.

Which means, you can of course hack an AC pump to be controllable :0) . But it will loose its structural integrity. DC pumps on the other hand are new, at least in the segment we are interested. Hence it will take some time for them to become as reliable as the AC pumps. But they will almost always take less energy and offer more controllability (and be expensive)

Not very related to the topic, but just an FYI , that most of our consumer electronics is DC based. Its due to some historical events (and very little engineering reasons) that we run electrical grids in AC. This whole thing is not super logical or efficient. Put other way, future home might have DC supply straight. and the consumer electronics dont have to ship their individual transformers and rectifiers

Ah. The famous Nicholi vs Tommy battle

ksed · Jan 20, 2018

@Brew12 Where is your post on the differences.

Brew12 · Jan 20, 2018

Ranjib said:
From my limited understand, all pumps work in DC.

Actually, you have this backwards. All pumps work in AC. This is why DC pumps need a controller. The controller takes the AC, turns it to DC, then turns it back to a variable form of AC. If it doesn't have carbon brushes connecting the rotor to the stator, it isn't a DC motor.

ksed said:
@Brew12 Where is your post on the differences.

Thanks for the invite! It is here.
https://www.reef2reef.com/ams/ac-and-dc-pumps-not-as-different-as-you-may-think.86/

DCR · Jan 20, 2018

marvelousone said:
Is the pressure drop different between the two. EX. 6foot pipe the pressure drop is the same.

The pressure drop through the piping only depends on the flow rate through it. If the actual flow rate is the same, the pressure loss will be the same. The flow/head of performance of different pumps will vary and that will obviously affect the actual flow, but if the head curves are the same, the flow rate will be the same.