Humming A/C

[Mook Johnson]

I recently bought a newly built house with a Carrier A/C system. On
move-inday the A/C was quiet whne turning on with little moretha fan hum.
I was concerned because the builder placed it outside the wall of my
bedroom.

after about 6 months of use in texas (hot) it gradually got a 60Hz humm that
is quite noticable in my bedroom. I checked with my neighbors units and
there units sound the same so I don't think the A/C is defective (A/C bills
are inline)

As there anything I can do to reduce the hum?

 

[martin griffith]

On Tue, 21 Dec 2004 13:03:17 GMT, in sci.electronics.design "Mook
Johnson" <mook@mook.net> wrote:

I recently bought a newly built house with a Carrier A/C system. On
move-inday the A/C was quiet whne turning on with little moretha fan hum.
I was concerned because the builder placed it outside the wall of my
bedroom.

after about 6 months of use in texas (hot) it gradually got a 60Hz humm that
is quite noticable in my bedroom. I checked with my neighbors units and
there units sound the same so I don't think the A/C is defective (A/C bills
are inline)

As there anything I can do to reduce the hum?


Antivibration mountings might be a start, its probably not an

"electonically solvable problem"



martin

Serious error.
All shortcuts have disappeared.
Screen. Mind. Both are blank.

 

[Rene Tschaggelar]

Mook Johnson wrote:

I recently bought a newly built house with a Carrier A/C system. On
move-inday the A/C was quiet whne turning on with little moretha fan hum.
I was concerned because the builder placed it outside the wall of my
bedroom.

after about 6 months of use in texas (hot) it gradually got a 60Hz humm that
is quite noticable in my bedroom. I checked with my neighbors units and
there units sound the same so I don't think the A/C is defective (A/C bills
are inline)

As there anything I can do to reduce the hum?

I guess, the humm comes from the mechanics. The motor is an
asynchronoeus machine rotating at very close to 60Hz halves,
or 1800 revs. Any wear or load sounds like a regular hum.
How about mounting shock absorbers or reducing the mechanical
coupling to sound ?

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

 

[Active8]

On Tue, 21 Dec 2004 13:03:17 GMT, Mook Johnson wrote:

I recently bought a newly built house with a Carrier A/C system. On
move-inday the A/C was quiet whne turning on with little moretha fan hum.
I was concerned because the builder placed it outside the wall of my
bedroom.

after about 6 months of use in texas (hot) it gradually got a 60Hz humm that
is quite noticable in my bedroom. I checked with my neighbors units and
there units sound the same so I don't think the A/C is defective (A/C bills
are inline)

As there anything I can do to reduce the hum?

Custom homes these days often have sound absorbing sheet rock around
the bathroom to keep the noise from getting out. Maybe that (not
around the BR, of course) and the shock mounts would help.
--
Best Regards,
Mike

 

[lemonjuice]

Though a motor can be modelled as a transformer due to its inductive
nature , the sound frequencies are rather different from what seems to
be the problem. Maybe the presence of harmonics in the load current and
voltage contribute, as due to the em forces due to leakage currents in
the motor windings that may cause internal vibrations . I'd still think
the mechanical component dominates .... but those low frequency em
origin noises are also there.

 

[Terry Given]

lemonjuice wrote:

Though a motor can be modelled as a transformer due to its inductive
nature , the sound frequencies are rather different from what seems to
be the problem. Maybe the presence of harmonics in the load current and
voltage contribute, as due to the em forces due to leakage currents in
the motor windings that may cause internal vibrations . I'd still think
the mechanical component dominates .... but those low frequency em
origin noises are also there.

Dont forget magnetostriction, and of course that dead whit guy, Newton -
the stator (and rotor) windings are well secured for a good reason.

Cheers
Terry