TEFC Motors for HVAC Applications 4

[IBechir]

Greetings

I came across the below statement in a HVAC pump handbook regarding TEFC motors. Can anyone explain please?

"Totally enclosed, fan-cooled motors are available for applications where the motor is wetted periodically. It should not be used for
routine motor applications in this industry."

Thank you

 

[Artisi]

Sounds clear to me - use drip-proof motors in all applications unless there is any chance of moisture gaining entry into the motor - in which case TEFC should be used.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[IBechir]

You're right stupid question on my part; wish the author did not phrase it like he did (why should a motor be wetted periodically?).

 

[Artisi]

Yes, could have been worded in a more meaningful manner.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[EnergyProfessional]

One wouldn't wet them on purpose.. but when there is a leak etc. it can get wet.

TEFC are much better motors than open motors. another benefit is dirty air can't get in the windings and coat them (and burn them out) like in open motors.

 

[RossABQ]

I believe the only reason not to use them in "routine" HVAC applications is cost. If they are in the airstream (larger air handlers) they are a good idea.

 

[EnergyProfessional]

Not sure what size of pumps you specify, but the good ones typically have TEFC motors.

Unless you can guarantee complete cleanliness, I wouldn't use open motors.

there are other things that tell if a motor is good or not.... OEM can undersize windings in a TEFC and use cheap bearings. but in general go with the better motor.

 

[Artisi]

Think if you like to check the major motor suppliers and fire pump regulations UL/FM in particular you will see that the majority of all fire pump motors are ODP.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[EnergyProfessional]

a fire pump operates maybe two hours during its life during a fire and maybe some testing. An HVAC pump may run 24/7 or at least few thousand hours a year.
A fire pump also is housed in a clean and fire separated room.

So that is not a good comparison. Dirt on open motors is an issue over long running time since the windings overheat and the insulation degrades. If your fire pump experiences similar exercise you probably should call the fire department to extinguish your building

 

[Artisi]

My error, for unknown reason my thinking (or non thinking) changed from HVAC to fire pump .


It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[pretendfarmer]

I typically recommend using TEFC motors whenever the equipment is in a new construction area simply because ODP motors can suck up a lot of dirt. A lot of times the equipment is run several months before final completion. During those times the mechanical room is typically very dirty. An ODP motor will tend to suck up the dirt and take out the bearings. A TEFC motor holds up better in a dusty dirty environment.