Mag drive 18 heat issues?

[gskidmor]

it's obviously less than trivial - the water in that test would have heated to ambient anyways, without the pump and heater - it's just how energy transfers. The real discussion is how much is tranferred after ambient. Not nearly as much by the pump as is done by the heater, hence there is a significant transfer of energy to a form other than heat - that post you provided more than proves that.

[gskidmor]

I do agree - I think we're arguing slightly different points... Oh well, it's not the first time I've misunderstood someone!

[gskidmor]

I should have read your entire post fully - I would have to think about that some more, but if a 25 watt heater can be used to heat 5 gallons effectively, I would say a little less than that

[sirreal63]

It seems that the main point remains the same, reduce the wattage from the equipment and the heat will be less. I did this very thing in about 2004/5 by cutting my total pump wattage in half, it was at this time I retired my chiller. The only change was the pump wattage and the reduction of my electric bill. The heat imparted to the room is still effecting the tank unless removed from the room.

Interesting discussion and can understand there may not be a total conversion but the difference seems to be very small.

[gskidmor]

lilc64 - sorry for hijacking, it got way of topic quickly!

[gskidmor]

sirreal63 - Correct. Efficiencies are improving every year - LED being a great example. You get as much light from 120 watts of LED as you do from 250 watts of MH (approximate) - so in the MH, the rest was mostly going to heat, so with the LED you're removing that 130 watts of heat

[sirreal63]

I think the OP got his answer, Mag pumps are not very efficient and there are much better choices.

[gskidmor]

yeah, I guess you're right

[James77]

Originally Posted by gskidmor

it's obviously less than trivial - the water in that test would have heated to ambient anyways, without the pump and heater - it's just how energy transfers. The real discussion is how much is tranferred after ambient. Not nearly as much by the pump as is done by the heater, hence there is a significant transfer of energy to a form other than heat - that post you provided more than proves that.

Yeah, but would you not agree that a very good amount of that has to do with water movement and the resulting ability to pass teh heat off to the air? Especially considering the heating patterns were so similar up to where it passed the tempeerature of the room?

[sirreal63]

Perhaps the important thing is the difference in 145 watts of heater and 140 watts actually imparted by a 145 watt pump (guestimate only) is negligible and for the most part and meaningless to the problem of heat in the tank. That slight difference in wattage isn't a problem, the total wattage is. At least to my pea brain.

[gskidmor]

Originally Posted by James77

Yeah, but would you not agree that a very good amount of that has to do with water movement and the resulting ability to pass teh heat off to the air? Especially considering the heating patterns were so similar up to where it passed the tempeerature of the room?

Yes

[gskidmor]

Originally Posted by sirreal63

Perhaps the important thing is the difference in 145 watts of heater and 140 watts actually imparted by a 145 watt pump (guestimate only) is negligible and for the most part and meaningless to the problem of heat in the tank. That slight difference in wattage isn't a problem, the total wattage is. At least to my pea brain.

also yes

[James77]

Originally Posted by gskidmor

I do agree - I think we're arguing slightly different points... Oh well, it's not the first time I've misunderstood someone!

Not really though.....my first reaction to your post was thinking that it was the common "but the pump is pumping water" statement. If you are arguing that the heat extends past the tank, then I do agree. All Im saying is that for the mot part, a pumps listed wattage will end up in the tank as heat. If 10% ends up outside it, it still stands that lower wattage higher flow pumps add less heat.

[lilc64]

amazing guys, i got my answer while gaining a greater understanding on the matter. Feel free to hijack my thread anytime this peaked my interest alot.

[James77]

Originally Posted by gskidmor

Yes

Oopsie....we all pretty much agree, its just kind of semantics and technicalities!

[gskidmor]

Originally Posted by James77

Not really though.....my first reaction to your post was thinking that it was the common "but the pump is pumping water" statement. If you are arguing that the heat extends past the tank, then I do agree. All Im saying is that for the mot part, a pumps listed wattage will end up in the tank as heat. If 10% ends up outside it, it still stands that lower wattage higher flow pumps add less heat.

Exactly

[gskidmor]

Originally Posted by James77

Oopsie....we all pretty much agree, its just kind of semantics and technicalities!

exactly too!

[gskidmor]

I was talking to a couple of my colleagues found a couple of great resources on pump efficiencies:

http://www.mcnallyinstitute.com/06-html/6-01.html

So pretty much anything after the conversion of the electricity to kinetic and potential energy (assuming you're using a sump) will be predominantly heat.

My friend that went and became a research post-doc in mechanical engineering stated that pump efficiency is generally measured thermodynamically. From an IEEE article:

eta = delta-p * Q/P

eta = Efficiency of the pump
delta-p = pressure rise accross the pump
Q is the discharge water flow rate
P is the power required to drive the pump

So when people are claiming that the pump is pumping the water, they're just not using the correct technical jargon - this article www.cee1.org/cee/mtg/09-06_ppt/pumps-2.pdf states that at least 10% of pumps run at less than 10% efficiency, so it could be that the mag 18 is very ineficient, but if you measure the other attributes, everything else will be produced as heat.