Heat load from pump motors 1

[71713]

I have two 125 hp motors in a room that pump water outside the room to a clearwell. I want to know how much heat is dissipated to the room to size exhaust fans.

After reading the recent thread about heat from conveyor motors (403-174079) it seems that the heat load to the room would be 785,494 BTUH assuming the pump and motor are each 90% efficient.

But that means all energy is converted to heat. In this case, should I just consider the losses from the inefficiencies of the pumps and motors as heat added to the room?

 

[AbbyNormal]

That would be 'motor in the space' driven equipment out of the space.

Don't worry about the 'work put into the pumped fluid'





Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[71713]

So even though the pump is in the room, because the liquid leaves the area, the driven equipment is considered "out of space". Correct?

 

[AbbyNormal]

I would just worry about the heat gain due to the inefficiency of the motor

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[marcoh]

A high efficiency motor of that size should be around 95% efficient which would reject nearly 7hp of heat.

 

[sterl]

If the inefficiencies of a pump went into its immediate surroundings as energy, and not into the pumped fluid, you would have red-hot pumps making noise like gas turbines in most applications over 50-Hp.

Unless you have a designed cooling loop on the pump, or fluid is hot enough to yield significant radiant heat, its the motor heat load that is of concern, which as marcoh indicates, represents the inefficiency of the motor...For (2)- 125's at 90% nominal efficiency, that comes out about 63,000 BTUH.

And considerably less if the pump only draws, say, 85 Hp steady state....