AC vs DC Pumps. Which Run Hotter?

[sleepydoc]

Not positive, but IIRC, a lot of the DC pump failures were controller failures that may have been related to poor heat dissipation on the design. Granted that without a controller a DC pump is just a door stop, and pump reliability means good design and manufacturing of the entire package, not just the motor block itself.

Re. The Echotech pumps - yes, there are people complaining that they are overheating when being run external at 100%, but I have to disagree that they are naive to try and run them this way. Ecotech is marketing and selling the pumps as internal or external with the stated capacity. If they can't be run at 100% without overheating then they should adjust their numbers and adjust their controller not to drive the pump faster than it can run. Likewise, if the pumps can't be run at 100% when used externally, they should say so on the box.

Part of the reason people buy and use these pumps is because they are quiet. No one disaggrees that Iwaki and Panworlds are great pumps, but if you have them in your living room, you tend to loose some ambiance. As I stated in that thread, many DC pumps seem to be designed poorly for external use - they have no fins or other effective means of radiating heat.

Hopefully it's just a matter of time before someone designs a better external DC pump and a better pressure rated DC pump.

It would also be nice to see an actual comparison of the various pumps and their flows and power consumption for various head pressures; Being simple beasts we humans like to over simplify things ("DC pumps are more efficient than AC pumps,") but reality is much more complex. Currently, it's very hard to make an educated decision due to the lack of clear data on the topic.

 

[LXXero]

yeah abyzz and red dragon are the top-tier DC pumps right now, and if you're willing to spend $800+ on a pump (more like $1500+ on the abyzz), probably not a bad choice at all, but when you can get an AC pump at half the cost, or less, that does the same thing? you can see why most people wont justify that....and ecotech and jebao seem to be the "low-end" tier of this game at the moment...

 

[LXXero]

All hardware only fails when your on vacation, late at night, or holidays. I have a love hate relationship with Apex, but use it (ok over use) to alert me to any inconsistency on my tank. I keep my own replacements on the shelf with instructions for a neighbor, grandpa, etc on how to change it. This includes plumbing fittings, etc.

lol, i've been the data center on call guy plenty of times at past jobs. I know murphy's law quite well....Oh you think just one hard drive is dead in your raid in the middle of the night? Nope, it's gonna be multiple, yay!! and just the right ones to kill your data. haha. glad i don't do much of that anymore, now i'm on the infrastructure automation side of things. everyone wants a private cloud these days cause they're too paranoid to use a public one. you get a cloud, you get a cloud, look under your seats, EVERYONE GETS A CLOUD!

I think i have a love/hate with cloud in general. I'm using samsung smartthings to do a lot of automation at home - and have written a bunch of code for that to integrate alarm system sensors in my spare time. It even includes flood sensors, but it's mostly typical door/window/motion/etc kinda stuff. With my integration, you can use motion sensors from your alarm for presence detection and do all kinds of fun stuff like turn on lights or try to achieve a certain temperature in areas with motion....oh you can be all sorts of fancy. When it works. Problem is, CLOUD. lol. if it can go wrong, it will. when you start adding remote providers into the mix and required-internet-connectivity for alerts, well ****, half your leaks and problems are gonna happen when power is going on/off....if your area has a major outage and internet/power go down, what use is any of that? even if you have a battery backup, what if a tree takes down a telephone pole and you lose power+internet+cable+phone+everything? because you know, that'll be exactly what ends up happening the time when **** does decide to hit the fan.

For a while I was debating should I use some z-wave flood detectors, and report via smartthings, or should I use the apex flood sensors, and report via apex fusion or whatnot...honestly, I know what i'd trust day-on-end over an apex OR smartthings and that's my good 'ol not-cloud alarm panel. That is one solid piece of equipment, wouldn't bat at an eye at it any day. I can pull data from that into the cloud no problem, too. Thing is, do I wanna go through all that effort? I don't even think they MAKE a wireless flood sensor, i'd have to take a wireless contact device and attach my own floor sensor to it, is it worth the effort? Maybe....we'll see. needless to say, it never hurts to have a plan a, b. and even sometimes c, lol.

all that kind of thinking has got me tempted to maybe convert to 2 separate return pumps to drive my manifold some day, but I have a feeling there's no reason to doubt my fluval in the short term, and my local LFS is who carries them and uses them on all his jobs, the owner usually has them around or can get parts easily. mind you he gets ecotech stuff too, but he hasn't used any vectra pumps yet last i talked to him, just the vortechs and radions. sometimes availability is more important than being picky, if you got some crazy expensive import pump from germany like an abyzz, heh, well, hopefully it's good enough it dont break right? but if it does, good luck getting parts for that in a pinch. you know what i mean?

 

[theatrus]

lol, i've been the data center on call guy plenty of times at past jobs. I know murphy's law quite well....Oh you think just one hard drive is dead in your raid in the middle of the night? Nope, it's gonna be multiple, yay!! and just the right ones to kill your data. haha. glad i don't do much of that anymore, now i'm on the infrastructure automation side of things. everyone wants a private cloud these days cause they're too paranoid to use a public one. you get a cloud, you get a cloud, look under your seats, EVERYONE GETS A CLOUD!

I think i have a love/hate with cloud in general. I'm using samsung smartthings to do a lot of automation at home - and have written a bunch of code for that to integrate alarm system sensors in my spare time. It even includes flood sensors, but it's mostly typical door/window/motion/etc kinda stuff. With my integration, you can use motion sensors from your alarm for presence detection and do all kinds of fun stuff like turn on lights or try to achieve a certain temperature in areas with motion....oh you can be all sorts of fancy. When it works. Problem is, CLOUD. lol. if it can go wrong, it will. when you start adding remote providers into the mix and required-internet-connectivity for alerts, well ****, half your leaks and problems are gonna happen when power is going on/off....if your area has a major outage and internet/power go down, what use is any of that? even if you have a battery backup, what if a tree takes down a telephone pole and you lose power+internet+cable+phone+everything? because you know, that'll be exactly what ends up happening the time when **** does decide to hit the fan.

For a while I was debating should I use some z-wave flood detectors, and report via smartthings, or should I use the apex flood sensors, and report via apex fusion or whatnot...honestly, I know what i'd trust day-on-end over an apex OR smartthings and that's my good 'ol not-cloud alarm panel. That is one solid piece of equipment, wouldn't bat at an eye at it any day. I can pull data from that into the cloud no problem, too. Thing is, do I wanna go through all that effort? I don't even think they MAKE a wireless flood sensor, i'd have to take a wireless contact device and attach my own floor sensor to it, is it worth the effort? Maybe....we'll see. needless to say, it never hurts to have a plan a, b. and even sometimes c, lol.

all that kind of thinking has got me tempted to maybe convert to 2 separate return pumps to drive my manifold some day, but I have a feeling there's no reason to doubt my fluval in the short term, and my local LFS is who carries them and uses them on all his jobs, the owner usually has them around or can get parts easily. mind you he gets ecotech stuff too, but he hasn't used any vectra pumps yet last i talked to him, just the vortechs and radions. sometimes availability is more important than being picky, if you got some crazy expensive import pump from germany like an abyzz, heh, well, hopefully it's good enough it dont break right? but if it does, good luck getting parts for that in a pinch. you know what i mean?

I hear you on all fronts . Too much equipment requires a live data connection to operate - thankfully the APEX is all local control but a lot of home automation stuff isn't.

And I always buy two of any key equipment, like a return pump. Availability of parts is a huge deal, since things do go wrong at the worst times.

 

[1jwampler]

Re. The Echotech pumps - yes, there are people complaining that they are overheating when being run external at 100%, but I have to disagree that they are naive to try and run them this way. Ecotech is marketing and selling the pumps as internal or external with the stated capacity. If they can't be run at 100% without overheating then they should adjust their numbers and adjust their controller not to drive the pump faster than it can run. Likewise, if the pumps can't be run at 100% when used externally, they should say so on the box.

I think I said I disagree with EcoTech not overbuilding or providing a warning, so I think we are on the same page here.

I do think before we harbor our poor reef creatures, we should do some homework on their life support systems. Again, as I said in a prior post, I'm inclined to over engineer, as an ATP, we don't replace broken parts, we replace parts that are expected to break a substantial time prior to the expected failure. When parts break, there is lots of paperwork, that often leads to shorter replacement/overhaul intervals so they don't break in the middle of a trans-pacific flight. So for many they may consider me to be overthinking systems and they're just fish or corals, but, to me if nothing else, they are substantial investment of both time and $$. For me mostly time, because no matter how much you want to spend you can't get a fully crashed tank back to show quality in 30 days, unless you want an even higher risk of crashing again.

So, prior to getting my 1st DC pump, I reviewed them, pros cons, etc. I do think it's a bit naive to take the manufacturers word for it. If the plan is to run 100%, a little research would reveal some very quiet efficient A/C pumps that are designed to run 100% 7x24x365. Why pay for a controller to set it to 100% and leave it? Why mount a controller and DC power supply if you don't have any tangible gains? While the Vectras are very quiet (almost silent), so are lots of A/C pumps with one cord and have years of history to attest to their reliability.

I love technology, but, I never use technology for the sake of technology, I think it's awesome when technology solves problems, IMHO too many people buy things because of marketing and get frustrated with the world when it does what they asked for not what they wanted. Again, EcoTech is NOT doing what they asked for or want in this case, so we agree, but, they do have some culpability in buying technology without understanding how it works. Honestly I would bet a flow meter at 4' would reveal less than 100gph from 100% to 95% and the same guys would have bought the pump if Ecotech's software set the flow to 3000gph rather than 3100gph (obviously less than that at 4'). But.... like every technology manufacturer EcoTech wanted to report the best numbers possible.

 

[LXXero]

i suspect the motor block itself is OK to run at that GPH if the pump works at 100% when underwater. i mean if that's truly the max of the motor, they should have designed the pump to handle that heat output. limiting it in software would prevent the issue, but better design would have allowed for the higher GPH. of course if they were really smart, they'd have it auto-ramp down the speed when the temperature gets too high. I have LED flashlights that do stuff like this....

ultimately it really sounds like insufficient heatsinking on the pump design

plus most of these submersible pumps are big chunks of plastic. a proper externai AC pump is usually metal bodied and some even have fans. but if you're going with the whole hybrid submersible/external pump, then you really need to make sure there's enough of a heatsink under that plastic. so really, the pump probably needs to be slightly bigger to add some more heat absorbing mass to it in order to properly run externally at motor's maximum speed.

 

[alton]

i suspect the motor block itself is OK to run at that GPH if the pump works at 100% when underwater. i mean if that's truly the max of the motor, they should have designed the pump to handle that heat output. limiting it in software would prevent the issue, but better design would have allowed for the higher GPH. of course if they were really smart, they'd have it auto-ramp down the speed when the temperature gets too high. I have LED flashlights that do stuff like this....

ultimately it really sounds like insufficient heatsinking on the pump design

plus most of these submersible pumps are big chunks of plastic. a proper externai AC pump is usually metal bodied and some even have fans. but if you're going with the whole hybrid submersible/external pump, then you really need to make sure there's enough of a heatsink under that plastic. so really, the pump probably needs to be slightly bigger to add some more heat absorbing mass to it in order to properly run externally at motor's maximum speed.

You hit the nail on the head! The biggest complaint on the L1 is the amount of heat it puts out running at 100%, but compared to my PX40 which does not have a fan like the Pan World 50PXX it gets very warm almost hot to the touch, but it has a metal case and mine has lasted 8+ years running at those temps. The question is can the plastic the L1 is made from handle that heat? I only replaced my Pan Worlds because of the control of the flow, hopefully my M1 will last the 10 years my Pan World 50 PXX has? FYI the PX40 and PXX50 are both quiet, my overflows made more noise.

 

[Chicago]

ok so i have iwake md 100rlt running my becket skimmer for a large tank..the pump seems to be the right size for the skimmmer.. large one.

will i lose a few degrees by switching to a dc but submerssible.. thanks

 

[slief]

ok so i have iwake md 100rlt running my becket skimmer for a large tank..the pump seems to be the right size for the skimmmer.. large one.

will i lose a few degrees by switching to a dc but submerssible.. thanks

The DC pumps are not well suited for a Beckett skimmer. Your Iwaki is a pressure rated pump and a big one at that. I can only assume you are running a dual beckett or a very large beckett skimmer since you are using the MD100. When I ran a dual beckett, that is the pump I ran.

First, beckett skimmers need pressure rated pumps for the beckett valves to operate properly. Without a pressure rated pump, they don't work anywhere near the same. Especially the larger beckett skimmers. Then there is the size of the pump. Given that the MD100 is one of the largest pressure pumps in its class, there aren't really any reasonably priced DC pumps that would even come close to matching that pump at the head pressure generated by the beckett valves. The only option currently available in a high output DC style pump that would perform well would be one of the larger Abyzz pumps. Honestly, I would suggest sticking with the Iwaki. There really isn't a better pump to replace it with. Now if you have a single beckett skimmer, you could probably downsize to a smaller Iwaki but that also depends on the size of the skimmer.

 

[bif24701]

Let's say we're comparing a standard AC return pump like a Sicce, Eheim or Tunze with a new generation controllable DC pump (Tunze, Vectra). Both are being used as a submersible.

Lets say the the AC Pump moves 600 GPH and the DC pump moves the same quantity (600 GPH). Do the DC pumps put less heat in the water even though they are moving the exact same amount of water? Or is heat output about the same for all? Is DC inherently more efficient somehow?

Reading posts on the topic, many comments seem to indicate that the DC pumps run cooler by nature, while doing the same amount of work. Is this the case? If so, why? What's the science or physics behind this? And is the difference appreciable or so small that it shouldn't be a practical consideration?

I'm not a PHD in physics but according to the laws of thermodynamics the pump that consumes less power could not generate more heat. Assuming that friction is about the same for both.


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[ca1ore]

ok so i have iwake md 100rlt running my becket skimmer for a large tank..the pump seems to be the right size for the skimmmer.. large one.

will i lose a few degrees by switching to a dc but submerssible.. thanks

That's hard to say. The large external fan driven Iwaki pumps consume a lot of electricity, but much of it is expelled into the air rather than into the water. I imagine the DC pump will consume less, but since it's submerged, most of that wattage ends up in the water as heat. Also, I agree with Scott, not sure that a DC pump is going to perform well on a beckett skimmer. I tried my ETM Vectra on my MTC mazzei skimmer and it performed poorly.

 

[bif24701]

That's hard to say. The large external fan driven Iwaki pumps consume a lot of electricity, but much of it is expelled into the air rather than into the water. I imagine the DC pump will consume less, but since it's submerged, most of that wattage ends up in the water as heat. Also, I agree with Scott, not sure that a DC pump is going to perform well on a beckett skimmer. I tried my ETM Vectra on my MTC mazzei skimmer and it performed poorly.

In this case the Iwaki transmits almost zero heat to the water. One of the reasons they are great.


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[ca1ore]

No, they're not almost zero. But much less than a non fan cooled or submersed pump.