DC pumps:huge power savings, really?

[gridley]

I'm certainly no electical enginer, but when choosing my pumps I spoke with an electrical enginer. His recommendation - without hesitation was to go with DC equipment if possible.

Questionable water flow ratings from manufactures aside, a DC pump will use less power to move an equal mount of water compared to an AC pump. DC is more efficient. One advantage of DC is that the speed of the pump can be controlled thereby reducing the power consumed. An AC pump is either on or off - full power use or nothing. A DC pump, if it comes with a speed controller, can be set for a lower speed (lower wattage use) if you do not need the full water flow. I have my Waveline 5000 set at the third of six speeds which provides me with plenty of water flow and uses half the full wattage (approx 20 watts).

[ocean diver]

Can someone post a picture of how these pumps hook into the sump. Thanks

[nrosdal]

Originally Posted by ocean diver

Can someone post a picture of how these pumps hook into the sump. Thanks

here is my dc5000:

[intarsiabox]

Originally Posted by gridley

An AC pump is either on or off - full power use or nothing. A DC pump, if it comes with a speed controller, can be set for a lower speed (lower wattage use) if you do not need the full water flow.

Not really, you can get VFD's (variable frequency drives) to control AC pumps. A lot of commercial/industrial buildings use this method for their pumps and fans to cut down on energy costs. Small VFD's have come down in price a lot but whether the cost of adding one would save you any money in the long run or not I couldn't say, and not at all if you are just going to run the pump at 100% all day long. Not all motors are VFD compatible either so that is something else to confirm. If I were starting from scratch and needed a return pump I would go with a DC model if it was as capable as a similarily priced AC pump in an instant.

[mark]

Originally Posted by intarsiabox

Not really, you can get VFD's (variable frequency drives) to control AC pumps. A lot of commercial/industrial buildings use this method for their pumps and fans to cut down on energy costs. Small VFD's have come down in price a lot but whether the cost of adding one would save you any money in the long run or not I couldn't say, and not at all if you are just going to run the pump at 100% all day long. Not all motors are VFD compatible either so that is something else to confirm. If I were starting from scratch and needed a return pump I would go with a DC model if it was as capable as a similarily priced AC pump in an instant.

Not to forget by restricting outlet of AC pump like the Barracuda, flow and power draw will decrease.

Sphelps, 4m and 4000l/h @ 85w still sounds to good to be true as that 3-4X the efficiency of the Reeflo

[gridley]

Originally Posted by intarsiabox

Not really, you can get VFD's (variable frequency drives) to control AC pumps. A lot of commercial/industrial buildings use this method for their pumps and fans to cut down on energy costs.

Ahaa - I get to learn something new everyday! LOL

Originally Posted by mark

Not to forget by restricting outlet of AC pump like the Barracuda, flow and power draw will decrease.

Sphelps, 4m and 4000l/h @ 85w still sounds to good to be true as that 3-4X the efficiency of the Reeflo

I'm not sure about this - unless the Barracuda operates differently from other pumps, the ability to restrict the outlet does reduce flow, but that isn't linked to power draw - reducing the output/flow typically increases the back pressure on a pump but I'm not sure that it reduces power useage.

[lastlight]

That effect has been measured for sure with the reeflo pumps.

[sphelps]

Originally Posted by gridley

Ahaa - I get to learn something new everyday! LOL



I'm not sure about this - unless the Barracuda operates differently from other pumps, the ability to restrict the outlet does reduce flow, but that isn't linked to power draw - reducing the output/flow typically increases the back pressure on a pump but I'm not sure that it reduces power useage.

Power draw will reduce slightly as head pressure increases, this is typical for most centrifugal style pumps.

You can see in the spec sheet how the power drops.

[sphelps]

Originally Posted by mark

Sphelps, 4m and 4000l/h @ 85w still sounds to good to be true as that 3-4X the efficiency of the Reeflo

I run two of the waveline 10000s and I some what agree that perhaps the flow-rate is exaggerated but I also use to think the power consumption was higher due to how hot the power supplies would get but after measuring the actual power consumption to be right on the money (85W full power) I seem to think the flow rate is likely accurate as well. I'm not sure why the manufacturer would lie about it. However what the pump curve really looks is probably key here, I just drew a typical curve line to give an idea what it probably looks like, doesn't mean it's accurate. Worst case you could draw a linear line, I've never seen a centrifugal pump do worse than linear.

If someone hasn't tested these pumps before my next sump break down I might do a little test to see what these pumps actually put out but until them I'm pretty satisfied with manufacture specs being accurate.

[StirCrazy]

Dc pumps use less power for the same work. I know this is true because of what we were taught in ac/dc motors and i have seen the difference in my new furnace. We replaced and ac fan furnace with a dc powered fan furnace. I run my fan 24/7 365 days a year to try keep the basmemt and up stairs reasonably close in temps and what we have seen is a 20 buck a month drop in the power bill with no other changes.

So if you have the option of going dc do it. Aside from the lower power consumption the fine speed controle is better.
Steve