closed loop question

[wmboots]

I started running a closed loop system in my 150 gallon display using a little giant pump. First things I noticed was the noise (sounds like I'm in a chiller plant of a school or high rise building) and the heat coming out of the back end of motor.
Going by heat emanating from back end of pump am I to assume this heat is also being transferred to the water being pulled and pushed through the pump head.
Is there a motor quieter and cooler running than little giant?
I have removed all heaters from the system and water is still above 84 degrees, way to hot in my opinion

 

[johniii]

I use little giant pumps on commercial lobster tanks all the time. They are usually pretty quiet. Is it a new pump. Are you putting to much back pressure on it.

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[wmboots]

pump isn't new and I really don't know how much back pressure I'm putting on the pump. I setup closed loop system with feed to pump using 3/4" T'd inside of tank with 2 arms extending 24" each with 1/4" holes drilled every 1.5" with the holes going thru front and out the back of the pipe plus a 1/4" hole drilled in the end caps. Return is accomplished through 2 - 3/4" lines one at each end of the tank.
Do you think this is causing to much back pressure? As for noise I hear the pump whining standing outside of the room where I have the tank

 

[grouper therapy]

Back pressure will not cause that kinda of noise. I'd say the bearings are going bad.

 

[johniii]

grouper therapy;752298 wrote: Back pressure will not cause that kinda of noise. I'd say the bearings are going bad.

+1 on the bearings

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[grouper therapy]

Bill there are more efficient and quieter pumps for closed loops (dart, snapper, sicce ho) but they would all require much larger pipe. 1.5" and up

 

[wmboots]

thanks for the info, I would agree with the bearing issue, as for back pressure from the info I gave do you see any potential for back pressure. I thought I was giving the pump plenty of pipe size and openings to keep the supply and return close enough in balance. Interesting the supply opening for the pump is half inch.

 

[grouper therapy]

Depending on the pump performance curve but I would think 3/4" is sufficient. A closed loop has no head pressure only friction head loss but it would be minimal in this scenario. A little head pressure may actually quieten the pump some.