Re: AC repair question
Deodiaus
I am buying a
AO Smith DL1056 1/2 HP Direct Drive Blower Motor
motor, which needs a 10 mF capacitor (according to manufacturer's
specs),
but the AC guy put in a 7.5 mF cap.
Any reasons why he would do that other than that's what he had
available (because he had to make a special run to grainger anyway?
Archimedes' Lever
wrote:
It will likely work, but it is almost certain he got that because it
was all that was available or because he thought it was the right animal
for the job.
Stormin Mormon
--
Christopher A. Young
Learn more about Jesus
www.lds.org
.
"Deodiaus" <deod...@yahoo.com> wrote in message
news:a7166cd5-854d-405a...@b14g2000yqd.googlegroups.com...
Deodiaus
http://americanhvacparts.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=MOT2426003&Category_Code=fasco-luxa
which as you can see here also comes recommended with a 7.5 MFD cap,
but the manufacturer suggests 10 MFD.
God is Dead
-Nietzsche
Tzortzakakis Dimitrios
? "Deodiaus" <deod...@gmail.com> ?????? ??? ??????
news:ca72dab6-4148-4e2d...@a36g2000yqc.googlegroups.com...
have no idea why they recommend 10 uF, since the website has a link to a GE
7.5 uF, and the electrician put a 7.5 uF.
Gott ist tod.
(your signature in German).
(Pronounced toont).
--
Tzortzakakis Dimitris
major in electrical engineering
mechanized infantry reservist
hordad AT otenet DOT gr
Deodiaus
The one I had was a one speed motor.
The new one is 3 speed.
Ok, which speed should I choose?
High, med, or low?
I guess a high speed will give you more circulation, but consume more
electricity.
Any estimates on how much this will affect my energy consumption?
Should I just punt and chose medium speed?
--
God is Dead
and I know German!
Dave M
Look at the nameplate on the old motor. The rated speed should be there.
Choose the same (or closest) speed on the new motor and wire it up
accordingly.
Make sure the new motor is wired to turn in the same direction as the old
motor. The capacitor hookup will determine the direction of rotation.
Rotation is always specified when looking at the shaft end of the motor.
Energy consumption will be modestly different on different brand motors, but
the difference will probably be negligible if the HP rating is the same,
regardless of the speed.
Cheers
Dave M.
Big Bob
> motor. The capacitor hookup will determine the direction of rotation.
If it is a reversible type motor, there will be 2 wires to change.
> Rotation is always specified when looking at the shaft end of the motor.
Again Bull shit. Have you ever looked in a motor catalog and wondered what
they mean when it says CCW Lead End?
Don't make statements not true that can cost somebody aggravation or money.
Stupid Rookie
PeterD
>Bull Shit!
>
>> motor. The capacitor hookup will determine the direction of rotation.
>
>If it is a reversible type motor, there will be 2 wires to change.
>
>> Rotation is always specified when looking at the shaft end of the motor.
>
>Again Bull shit. Have you ever looked in a motor catalog and wondered what
>they mean when it says CCW Lead End?
>
Care to post a reference to a catalog page that says that?
Dave M
news:soou45140joa8fu85...@4ax.com...
My, what venom!!! Cool down and let's converse without the profanity.
You're right ... when I spoke of the rotation, I knew what I wanted to
write, but I left out the pertinent word, which was "opposite". I meant to
say that the direction of rotation is almost always specified by looking at
the end opposite the shaft. My apologies to the OP for the error.
I don't have any books or catalogs on AC motor design and construction; I
was taught many years ago by an A/C professional installer and service guy
that the connection of the capacitor in the motor's circuit changes
direction of the motor, usually by changing the connection of the
capacitor's wires on the terminal board. Perhaps motor construction
techniques have changed over the years?
Dave M
PeterD
wrote:
>"PeterD" <pet...@hipson.net> wrote in message
>news:soou45140joa8fu85...@4ax.com...
>> On Fri, 3 Jul 2009 21:20:17 -0500, "Big Bob" <b...@l.net> wrote:
>>
>>>Bull Shit!
>>>
>>>> motor. The capacitor hookup will determine the direction of rotation.
>>>
>>>If it is a reversible type motor, there will be 2 wires to change.
>>>
>>>> Rotation is always specified when looking at the shaft end of the motor.
>>>
>>>Again Bull shit. Have you ever looked in a motor catalog and wondered
>>>what
>>>they mean when it says CCW Lead End?
>>>
>>
>> Care to post a reference to a catalog page that says that?
>
>My, what venom!!! Cool down and let's converse without the profanity.
Venom? I asked for a catalog reference page.
Profanity? None of the words I wrote could ever be considered
profanity.
Maybe you should learn some more of the English, such as the
definition of venom, profanity, and heck every word that I wrote.
Deodiaus
the capacitor might be of the wrong capacitance.
The problem with buying one off the shelf is that its tolerance might
be off enough to throw the engine off.
Does anyone know how to calculate the torque for an engine with a
capacitance?
I use to know this 30 years ago, but now, don't even know how to
google this question properly!!
Using a 7.5 MFD cap did not work. I tried a 10 MFD cap, which worked
for 10 mins.
BTW, I found a cheap motor at
https://www.plumbersstock.com/product.html?partNumber=12476
Does anyone have experience with this brand,
PARTNERS CHOICE ??
TheQuickBrownFox
wrote:
> tolerance might
>be off enough to throw the engine off.
They are called motors. Your credibility has taken a dive.
Wild_Bill
qualified, experienced person to take over the job.
A residential air system blower motor should work about the same with a
properly rated AC capacitor of 7.5uF or 10uF value (for a motor that's
marked for either a 7.5uF or a 10uF), with only a small difference in motor
speed.
These motors are typically PSC permanent split capacitor type motors, and
may be reversible, but may be designed to operate more efficiently/cooler in
one direction.
The motor you referred to is not a cheap motor, it's just not an exessively
inflated priced motor.
New surplus blower motors can be found at numerous surplus dealers for about
$30 or less, plus shipping.
--
Cheers,
WB
.............
"Deodiaus" <deod...@yahoo.com> wrote in message
news:f47b22c7-bfd1-438c...@n11g2000yqb.googlegroups.com...
Deodiaus
on motors explained. 30 years ago, I had someone explain this to me
in a class, but I have forgotten it all.
Any good descriptive web sites??
BTW, does anyone know of cheaper motors on the web?
https://www.plumbersstock.com/product.html?partNumber=12476
The above site lists some substitute motors, but some just hang my
browser .
Deodiaus
http://www.tpub.com/content/neets/14177/css/14177_96.htm
The motor did not rotate when I put in a 7.5 MFD cap. It worked for
about 10 mins for a 10 MFD capacitor.
It was making a squeaking sound, before it cut out. I am trying to
figure out if it is a simple repair in the starter winding and return
the motor, or if I need to replace the motor.
BTW, I look at this as a learning experience. So, unless I fry myself
or the house, nothing is lost.
I have messed up things in my life, but I think I have fixed many a
things too.
I know the difference between an engine and motor. An engine turns
mechanical energy into electricity. A motor turns electrical energy
into mechanical. You can usually run one in reverse to get the
behavior of the other.
Wild_Bill
Your progression to this point has been backwards.
When the motor hums instead of starting, it's not because the value needs to
be 8.645789uF, it's because the motor is not wired properly.
You need a qualified, experienced person to take care of the installation.
--
Cheers,
WB
.............
"Deodiaus" <deod...@yahoo.com> wrote in message
news:b6e02d73-4a51-42b1...@d4g2000yqa.googlegroups.com...
Archimedes' Lever
wrote:
> 30 years ago, I had someone explain this to me
>in a class, but I have forgotten it all.
Obviously you forgot a lot. You referred to an electrical motor as an
"engine".
Deodiaus
Someone suggested looking at the bearings. What do I look for,
excessive wear?
My electrician friend recommended just replacing the motor rather than
trying to diagnose it farther than that.
However, my time is worth about $5/hr, so if I can repair it in less
than I day, I have come out ahead.
cjt
> It sounds as though you are in over your head, and it's time to get a
> qualified, experienced person to take over the job.
>
> A residential air system blower motor should work about the same with a
> properly rated AC capacitor of 7.5uF or 10uF value (for a motor that's
> marked for either a 7.5uF or a 10uF), with only a small difference in
> motor speed.
why would the speed change?
Tony Hwang
You and your frieed lectrician better learn what is the function of
capacitor for the motor first. If same value is not available always
replace it with next higher value. Same with W.V. You do the math to see
why it is so.
Deodiaus
http://boatandrvaccessories.com/43587.htm
Does anyone know where I can buy one for $30?
ps1. I am interested in the start capacitance, (the motor makes the
humming sound trying to start up).
ps2. my friend the electrician is not the same as the AC repairman
and not the same as the earlier guy who put in the 7.5 MFD cap (which
seems to be the one that the sites sell with it [A.O. Smith recommends
10 MFD]).
ps3. The reason I was looking for the calculations is that I can see
how sensitive they are to a change in capacitors.
The Daring Dufas
I can walk in to several places here in town
and buy one for less. $60 plus $15 shipping?
Kinda runs the price up.
TDD
Wild_Bill
a major speed change for the previously discussed values of 7.5uF to 10uF.
For the theoretical explanations, try a book with a detailed section on
Permanent Split Capacitor (PSC) type AC motors.
These motors have been used for deades and are still presently utilized in
many applications from fans and blowers to fractional HP gearhead motors.
PSC type motors differ greatly from split-phase capacitor start motors.
--
Cheers,
WB
.............
"cjt" <chel...@invalid.invalid> wrote in message
news:4A5163B...@invalid.invalid...
Anon
If the capacitor was a starting capacitor it won't make any difference in
speed, as it is only use to start the motor rotating, and is disconnected
once it is spinning near operating speed. The motor windings will determine
the speed and torque while running.
Most AC blower motors use a running capacitor that stays active while the
motor runs. A running capacitor shifts the Alternating Current sine-wave
between the windings to give the motor torque. A larger value capacitor
will give more torque, and perhaps a little more speed. Induction motors
are greatly affected by the load upon them. If the load is less than the
maximum, a smaller capacitor value is used to keep the rotation speed within
reasonable parameters. An induction motor run without any load will run too
fast and the windings will overheat and break down the lacquer insulation
causing an internal short.
If the motor just hums and does not rotate - there is something else wrong.
A failed capacitor results in this same symptom and is the easiest solution
to try, hence the reason it was replaced. Even a 4�F or 5�F capacitor
should turn the motor. Check the bearings by rotating the unloaded motor
shaft - it should rotate fairly easily. Usually sealed ball bearing sets
are used in these motors, pressed onto the shaft - replacement will require
a bearing puller.
If the blower is directly attached to the shaft, the only bearings to check
are in the motor. If it is a belt driven set-up (older), the bearings on
the squirrel cage will be suspect.
If the motor spins freely, but still only hums on start up, either a bad
connection to the capacitor (or other component) or a short or break in the
motor windings, not to mention another capacitor failure. These motors tend
to have very fine and compact winding wraps and then take a lacquer bath,
making service difficult if not impossible. If there is a short in the
motor, the first place to check is the bundle where the insulated wires are
soldered to the winding wires, if that is the connection method.
Scott
daestrom
> "Deodiaus" <deod...@yahoo.com> wrote in message
> news:0dd6cdad-d3b3-4d31...@t13g2000yqt.googlegroups.com...
>> I found one for $65 shipped at:
>> http://boatandrvaccessories.com/43587.htm
>>
>> Does anyone know where I can buy one for $30?
>>
>> ps1. I am interested in the start capacitance, (the motor makes the
>> humming sound trying to start up).
>> ps2. my friend the electrician is not the same as the AC repairman
>> and not the same as the earlier guy who put in the 7.5 MFD cap (which
>> seems to be the one that the sites sell with it [A.O. Smith recommends
>> 10 MFD]).
>> ps3. The reason I was looking for the calculations is that I can see
>> how sensitive they are to a change in capacitors.
>>
>>> The motor you referred to is not a cheap motor, it's just not an
>>> exessively
>>> inflated priced motor.
>>> New surplus blower motors can be found at numerous surplus dealers for
>>> about
>>> $30 or less, plus shipping.
> Induction motors
> are greatly affected by the load upon them. If the load is less than the
> maximum, a smaller capacitor value is used to keep the rotation speed within
> reasonable parameters. An induction motor run without any load will run too
> fast and the windings will overheat and break down the lacquer insulation
> causing an internal short.
>
Not even close. Induction motor speeds vary little from no-load to
full-load (slip from no-load to full-load of typical induction motor
[not some ceiling fan junk] is <1 to 3 % of synchronous speed). Running
completely unloaded is perfectly fine and the windings of an induction
motor will *not* overheat in that situation. (hint, the motor draws less
current when it's unloaded)
> If the motor just hums and does not rotate - there is something else wrong.
> A failed capacitor results in this same symptom and is the easiest solution
> to try, hence the reason it was replaced. Even a 4�F or 5�F capacitor
> should turn the motor. Check the bearings by rotating the unloaded motor
> shaft - it should rotate fairly easily. Usually sealed ball bearing sets
> are used in these motors, pressed onto the shaft - replacement will require
> a bearing puller.
>
> If the blower is directly attached to the shaft, the only bearings to check
> are in the motor. If it is a belt driven set-up (older), the bearings on
> the squirrel cage will be suspect.
>
> If the motor spins freely, but still only hums on start up, either a bad
> connection to the capacitor (or other component) or a short or break in the
> motor windings, not to mention another capacitor failure. These motors tend
> to have very fine and compact winding wraps and then take a lacquer bath,
> making service difficult if not impossible. If there is a short in the
> motor, the first place to check is the bundle where the insulated wires are
> soldered to the winding wires, if that is the connection method.
>
These are good troubleshooting points. But your statement earlier about
motor speed/load is off.
daestrom
daestrom
> Any guesses as to what is wrong with the winding?
> Someone suggested looking at the bearings. What do I look for,
> excessive wear?
Well it's possible that this is still the original problem and the
capacitor was not bad to begin with.
The symptoms point to something in one of the two winding circuits.
There are two separate windings in a single phase induction motor. In
many motors one of the windings is only energized during starting and
then turned off by a centrifugal switch. But this thread has been
talking about capacitive run type (and that's common for blower motors)
so we can ignore problems with the switch.
If the two windings are energized from the same power source without any
capacitor at all, then no torque is developed and the motor sits and
hums. So one thing is it may be wired up wrong. Recheck your work
against the circuit diagram (often inside the panel or in a manual).
If the bearings or blower are seized up, the motor can't develop enough
torque to start spinning. Or you may get it started but the load is so
great that it overheats and shuts down. I think you mentioned it ran
for a while one time? When everything is turned off, you should be able
to easily turn the thing by hand, blower and all.
If one of the two windings has developed an open, then the other winding
alone can't develop torque to start and it will just hum. This *may* be
just an open in a connecting wire and would be easy to fix. But if it's
down inside the winding, rewinding a motor is quite a task and often not
worth the effort.
If your handy with an ohm-meter you can check for opens easy enough.
Just lift the leads and read between them. Be sure to turn off the
power though, ohm-meters tend to smoke when connected to live AC power.
daestrom
Anon
"daestrom" <daes...@twcny.rr.com> wrote in message
news:h30ii...@news6.newsguy.com...
Ah, I should have qualified that with "low-torque/low speed" induction
motors (less than 300 RPM) often found in smaller squirrel cage blower fans
and in some ceiling fans. I have not worked on many high torque, high speed
induction motors to consider them typical of induction motors. Low torque
motors are designed to carry a specified load and can run up to 25% faster
without that load. But I concede, a blower motor requiring a 10�F running
capacitor probably is a high torque induction motor that will not suffer
from heat-rise unless it is from the bearings.