heat transfer of submersible pumps
- Thread starter goby1
- Start date
BeanAnimal
Premium Member
You can figure out the tru power consumption of just about any device by comparing the heat it puts off to that of a purely resistive load...
Build an small insulated box (airtight) and put a 100W lightbulb in it. Measure the time it take the box to reach a state of temperature equillibrium...
No place your unknown device inside that same box (starting at room temp again) and measure the time it takes the air in the box to reach a stable temp.
The power used will be roughly the ratio of times multipled by 100w
So go toss your 8 54W t5s in a box (ballast and all) and the do the same for your 2 250 MHs (ballast and all). See which one really draws more current.
Did somebody try to say that 200W of LEDs is cooler running that 200W of incadescent? Hrmmm 200W is 200W
Why do I bring this up in a pump thread? Well everybody seems to go by the ratings on the side of hte pumps and ballasts. Or worse yet, they use a cheap meter of some kind to try and compare the power usage of different devices. I have seen web based equipment reviews that don't get it correct. Most of us can't afford a good True RMS meter, so we can't really measure the current draw of non sinusoidal loads. Switch mode power supplies, ballasts, and all kinds of other modern devices are not easy to measure.
So the question is, does that 140W pump really consume 140W?
Build an small insulated box (airtight) and put a 100W lightbulb in it. Measure the time it take the box to reach a state of temperature equillibrium...
No place your unknown device inside that same box (starting at room temp again) and measure the time it takes the air in the box to reach a stable temp.
The power used will be roughly the ratio of times multipled by 100w
So go toss your 8 54W t5s in a box (ballast and all) and the do the same for your 2 250 MHs (ballast and all). See which one really draws more current.
Did somebody try to say that 200W of LEDs is cooler running that 200W of incadescent? Hrmmm 200W is 200W
Why do I bring this up in a pump thread? Well everybody seems to go by the ratings on the side of hte pumps and ballasts. Or worse yet, they use a cheap meter of some kind to try and compare the power usage of different devices. I have seen web based equipment reviews that don't get it correct. Most of us can't afford a good True RMS meter, so we can't really measure the current draw of non sinusoidal loads. Switch mode power supplies, ballasts, and all kinds of other modern devices are not easy to measure.
So the question is, does that 140W pump really consume 140W?
This has been a very useful thread as I was about to purchase some power heads before I began reading it. As a result of these fascinating discussions, I gave up on a Natural Wave with Maxijets and, instead, bought two Seio 620's claiming to use only 8 W each. They are doing the job quite nicely for just $76 delivered. Thanks
How does the kill watt thing measure watts?
I wonder how efficient the new mag drive ecotech props are. Recall that the more efficient it is, the higher % of power goes to heat the water. One of the bottom lines is that the less the water movement, the less the thermal energy transferred to the water over time.
I like the idea of the ecotech device because it can be moved and doesn't require drilling. If these luxuries could be given up, I imagine that the diy crowd could have great success with a good bearing, a prop, and a quiet motor. I'd bet that the performance could match this pump for much less, and most importantly, with minimal research and assembly. I thought this relevant because of all the stir with these props lately.
I'm not sure how it would work out financially, but one might consider using cheap submersible powerheads attached to their temp controllers. Might as well get the flow if you need the thermal input.
G1
I wonder how efficient the new mag drive ecotech props are. Recall that the more efficient it is, the higher % of power goes to heat the water. One of the bottom lines is that the less the water movement, the less the thermal energy transferred to the water over time.
I like the idea of the ecotech device because it can be moved and doesn't require drilling. If these luxuries could be given up, I imagine that the diy crowd could have great success with a good bearing, a prop, and a quiet motor. I'd bet that the performance could match this pump for much less, and most importantly, with minimal research and assembly. I thought this relevant because of all the stir with these props lately.
I'm not sure how it would work out financially, but one might consider using cheap submersible powerheads attached to their temp controllers. Might as well get the flow if you need the thermal input.
G1
ChemE
New member
I run a MJ-600 converted to a Maxi-Stream 600 in my 55 and it is perfect. By perfect I mean all the circulation my reef can take, cost me $30 total, took 2 hours start to finish, and only draws 6 watts according to my Kill-a-Watt. Based on estimates from the Hitchhiker's Guide thread, it is moving in the neighborhood of 2,000 gph. For those skeptics, this is measured by clocking how long it takes to fill an empty 5 gallon bag placed underwater in front of the exit. There is a pretty good amount of error associated with such a measurement, so that number is probably +/- 10% but who cares?
