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View Full Version : running pumps int./ ext.?


troylee
05/14/2009, 08:01 AM
has anyone ever done any testing to see if it matters, if a pump runs internal or external, to see if it helps with heat transfer???i know both ways the heat still transfers but it seems like a catch 22........if you run a pump internal the heat will transfer but the water keeps it cooler........now if you run it external i would assume the pump does'nt transfer as much heat but maybe it does because it runs hotter........im asking because i was gonna put my new sump in today or tomorrow and wanted to know if it mattered or not before i go through all the hassles of running my return and skimmer feed pump ext.
tia.........

pbaldwin
05/14/2009, 08:51 AM
It really depends on the pump.

Some are designed to dump their waste heat into the water they are pumping and some are designed to be cooled by an external source.

For example an Eheim is designed to be cooled by the water it is pumping so its going to heat the water a similar amount if it is submerged or not.

An Iwaki is designed to be primarily air cooled and will impact a minimum amount of heat to the water it is pumping. Of course an Iwaki can not be run submerged...

troylee
05/14/2009, 09:06 AM
ok i im running a qo2200 to feed my skimmer and a mag18 for a return. both are ran internal as we speak but i was thinking about putting them external in my newsump..........im just trying to get my tank a little cooler trying different things before i invest in a chiller.....

james3370
05/14/2009, 09:18 AM
try a $10 desktop clip-on fan. i had one pointed at an open-top nano that had a halide & the fan made a 5-degree difference.....of course there was the increased evaporation

i'm gonna be running a mag 9 external for a closed loop & a little concerned about it getting hot. if it does, i'll probably have to put a fan on it

troylee
05/14/2009, 09:28 AM
i have fans simmiliar to what your talking about on my sump.......im just wandering if placing these pumps external if the tank will drop a degree or 2.......hmm.....

uncleof6
05/14/2009, 10:39 AM
<a href=showthread.php?s=&postid=15009616#post15009616 target=_blank>Originally posted</a> by troylee
i have fans simmiliar to what your talking about on my sump.......im just wandering if placing these pumps external if the tank will drop a degree or 2.......hmm.....

Getting some good pumps with good motors will reduce the heat input. Look at the power factors of the motors. With many of the "inexpensive" motors (pumps) the power factor is so low that most of the electrical energy is converted to heat (as in the power factor question on the front page right now..62% of the "power" is converted to heat.) Correcting the power factor will cut the heat down, but it is not something the "average bear" should try. Running external, will cut down on the heat transmitted to the water, and fans will cool the motor, but it will still be energy inefficient, and you will be adding the usage by the fan. Heat will still transfer to the water, because the impeller assembly is in contact with the motor (with a "magnetic drive" pump), whereas a shaft drive pump (impeller assembly separated from the motor) will transfer significantly less heat. ehhhh, you could probably care less about this, cause I am saying to buy a real pump:D , and I am power factor happy this morning.

Regards,

Jim

troylee
05/14/2009, 01:35 PM
well im not getting new pumps.lol........ so what would you suggest running internal or external???if i can get my tank down 2 more degrees im happy and im just curiuos if this will do it or not.......:)

stugray
05/14/2009, 02:57 PM
troylee,

Be careful trying to run the Mags External.

I have done it, but it makes me nervous.
The Mag volutes are very fragile, especially if hooked to rigid plumbing.

If I just bumped my Mag I could easily break the volute.

My sequence pumps, on the other hand, I could drop a 5 pond sledge on them and it would bounce off.

If you protect the Mag and run flex connects you will probably be fine.

As for the heat transfer - I'm not positive, but I would bet that it transfers more than 2X as much heat when submerged & shortens the life by ~1/2 when run externally.

Stu

therealfatman
05/14/2009, 10:36 PM
Stu and Uncle pretty much covered it all, but some would just simpllfy it and sat internal for winter and external for summer and always buy quality as that is usually where the "wattage in power" out difference is really apparent.