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Peter H
Guest
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 Posted: Tue Feb 15, 2005 5:27 am Post subject: HVAC Question |
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I'm hoping someone in this group will take the time to answer this for me.
I'm in the middle of a course on HVAC in high-rises. The instructor has
stated that the oil in the HVAC system should be checked regularly for
quality and impurities. She says that if refrigerant is detected in the oil
then there is a problem. I was always thought that there is oil in the
system with the refrigerant and that this oil lubricated the compressor
etc.and one would expect to find refrigerant mixed in with it. I thought
that this was why you are always told to let a newly delivered fridge stand
for an hour or two before turning it on, to let the oil drain back down into
the compressor.
What gives?
tia
Peter H |
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Dr. Hardcrab
Guest
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| Posted: Tue Feb 15, 2005 7:07 am Post subject: Re: HVAC Question |
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"Peter H" <peterh@notreallyrogers.com> wrote in message
news:HcmdnZ9ezN9F3IzfRVn-3Q@rogers.com...
| Quote: | I'm hoping someone in this group will take the time to answer this for me.
I'm in the middle of a course on HVAC in high-rises. The instructor has
stated that the oil in the HVAC system should be checked regularly for
quality and impurities. She says that if refrigerant is detected in the
oil
then there is a problem. I was always thought that there is oil in the
system with the refrigerant and that this oil lubricated the compressor
etc.and one would expect to find refrigerant mixed in with it. I thought
that this was why you are always told to let a newly delivered fridge
stand
for an hour or two before turning it on, to let the oil drain back down
into
the compressor.
What gives?
Sounds like your teacher needs to be a little more clearer on her |
explaination OR you need to get another teacher..... |
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Stormin Mormon
Guest
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| Posted: Tue Feb 15, 2005 8:45 am Post subject: Re: HVAC Question |
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Those big skyscrapers sometimes use semihermetic compresssors (like boat
motors, or car engines). Which have a crankcase for the oil.
Refrigerators do mix the oil and refrigerant, and so for refrig, that's
normal.
As to mixing th eoil and refrigerant, that's a new one to me, I do mostly
small stuff, not skyscrapers.
As for the new fridge, I think the major problem is oil in the piston. Cause
oil isn't compressable. I've seen a couple cases where folks tipped a fridge
to move it. When they plugged it right back in, it killed the compressor.
--
Christopher A. Young
Learn more about Jesus
www.lds.org
www.mormons.com
"Peter H" <peterh@notreallyrogers.com> wrote in message
news:HcmdnZ9ezN9F3IzfRVn-3Q@rogers.com...
I'm hoping someone in this group will take the time to answer this for me.
I'm in the middle of a course on HVAC in high-rises. The instructor has
stated that the oil in the HVAC system should be checked regularly for
quality and impurities. She says that if refrigerant is detected in the oil
then there is a problem. I was always thought that there is oil in the
system with the refrigerant and that this oil lubricated the compressor
etc.and one would expect to find refrigerant mixed in with it. I thought
that this was why you are always told to let a newly delivered fridge stand
for an hour or two before turning it on, to let the oil drain back down into
the compressor.
What gives?
tia
Peter H |
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TURTLE
Guest
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| Posted: Tue Feb 15, 2005 10:28 am Post subject: Re: HVAC Question |
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"Peter H" <peterh@notreallyrogers.com> wrote in message
news:HcmdnZ9ezN9F3IzfRVn-3Q@rogers.com...
| Quote: | I'm hoping someone in this group will take the time to answer this for me.
I'm in the middle of a course on HVAC in high-rises. The instructor has
stated that the oil in the HVAC system should be checked regularly for
quality and impurities. She says that if refrigerant is detected in the oil
then there is a problem. I was always thought that there is oil in the
system with the refrigerant and that this oil lubricated the compressor
etc.and one would expect to find refrigerant mixed in with it. I thought
that this was why you are always told to let a newly delivered fridge stand
for an hour or two before turning it on, to let the oil drain back down into
the compressor.
What gives?
tia
Peter H
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This is Turtle.
I'm not a high rise people. The only thing I can think of is if your flooding
back liquid freon to the compressor. If you take a oil sample. it will be
foaming up and you will have to wait for the freon to flash out of it. Maybe she
is thinking as it having a flood back of freon when the oil is foaming when
taking a sample.
i will just say this as to the answer awwww she must know something that i don't
know.
TURTLE |
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Duffaukid
Guest
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| Posted: Tue Feb 15, 2005 8:16 pm Post subject: Re: HVAC Question |
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On Mon, 14 Feb 2005 19:27:00 -0500, "Peter H"
<peterh@notreallyrogers.com> wrote:
| Quote: | I'm hoping someone in this group will take the time to answer this for me.
I'm in the middle of a course on HVAC in high-rises. The instructor has
stated that the oil in the HVAC system should be checked regularly for
quality and impurities. She says that if refrigerant is detected in the oil
then there is a problem. I was always thought that there is oil in the
system with the refrigerant and that this oil lubricated the compressor
etc.and one would expect to find refrigerant mixed in with it. I thought
that this was why you are always told to let a newly delivered fridge stand
for an hour or two before turning it on, to let the oil drain back down into
the compressor.
What gives?
tia
Peter H
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Have her show you the documentation of her source. It's quite
possibe that some reference manuals for large systems provide such
instructions.
dk |
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SQLit
Guest
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| Posted: Tue Feb 15, 2005 8:36 pm Post subject: Re: HVAC Question |
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"Peter H" <peterh@notreallyrogers.com> wrote in message
news:HcmdnZ9ezN9F3IzfRVn-3Q@rogers.com...
| Quote: | I'm hoping someone in this group will take the time to answer this for me.
I'm in the middle of a course on HVAC in high-rises. The instructor has
stated that the oil in the HVAC system should be checked regularly for
quality and impurities. She says that if refrigerant is detected in the
oil
then there is a problem. I was always thought that there is oil in the
system with the refrigerant and that this oil lubricated the compressor
etc.and one would expect to find refrigerant mixed in with it. I thought
that this was why you are always told to let a newly delivered fridge
stand
for an hour or two before turning it on, to let the oil drain back down
into
the compressor.
What gives?
tia
Peter H
|
I believe you will find in the real world, "if it aint broke don't fix it".
I have never heard of anyone taking and testing oil samples on refrigerant.
Unless there was a problem with the unit.
Every high rise I ever worked on had compressors and air handlers in a
mechanical room.
Cooling and heating was transferred either directly (air) or by another
medium (water).
Being the cost per square foot is so high the idea of huge duct work from
the roof or basement has not been used for years. At least not here. Then
there is the fire concern with large vertical ducts. |
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Matt
Guest
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| Posted: Tue Feb 15, 2005 9:24 pm Post subject: Re: HVAC Question |
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| I think she is saying she wants to mix fluids with you. |
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Geoman
Guest
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| Posted: Tue Feb 15, 2005 10:30 pm Post subject: Re: HVAC Question |
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"Peter H" <peterh@notreallyrogers.com> wrote in message
news:HcmdnZ9ezN9F3IzfRVn-3Q@rogers.com...
| Quote: | I'm hoping someone in this group will take the time to answer this for me.
I'm in the middle of a course on HVAC in high-rises. The instructor has
stated that the oil in the HVAC system should be checked regularly for
quality and impurities.
|
Yes, you can take oil samples and send them in to labs. These tests can,
depending on what you want tested, show if the compressor is running hot or
if there is some flooding, moisture, acid and other issues.
She says that if refrigerant is detected in the oil
| Quote: | then there is a problem.
|
I thhink she's talking about liquid here. You will always have some
refrigerant in the oil but saturated with refrigerant is a big problem. This
can result from migration or flood back.
I was always thought that there is oil in the
| Quote: | system with the refrigerant and that this oil lubricated the compressor
etc.and one would expect to find refrigerant mixed in with it. I thought
that this was why you are always told to let a newly delivered fridge
stand
for an hour or two before turning it on, to let the oil drain back down
into
the compressor.
|
I was told to let it settle down because of debris in the crankcase being
disturbed coud plug the cap tube. It doesn't matter for me because I always
heat the compressor up before plugging ours in.
I'm surprised she didn't mention a MegOhm reading being taken and logged as
well.
The reason she is talking about these topics is with typical large highrises
the compressors are very expensive. Parts can be limited if its an older or
specialty brand. It is normal to test centrifugals and screw compressors. I
remember before oil testing we would change the York centrifugals oil out
every year and hoped that it didn't need it more. Testing the oil took the
guess work out.
I also think its wise to check the quantity of oil in the system.
| Quote: |
What gives?
tia
Peter H
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Barr
Guest
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| Posted: Wed Feb 16, 2005 5:40 am Post subject: Re: HVAC Question |
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On Tue, 15 Feb 2005 03:45:29 GMT, "Stormin Mormon"
<cayoung61-#spamblock*-@hotmail.com> wrote:
| Quote: | Those big skyscrapers sometimes use semihermetic compresssors (like boat
motors, or car engines). Which have a crankcase for the oil.
Refrigerators do mix the oil and refrigerant, and so for refrig, that's
normal.
As to mixing th eoil and refrigerant, that's a new one to me, I do mostly
small stuff, not skyscrapers.
As for the new fridge, I think the major problem is oil in the piston. Cause
oil isn't compressable. I've seen a couple cases where folks tipped a fridge
to move it. When they plugged it right back in, it killed the compressor.
|
I know I should comment on this post but, I won't. Just
disreguard. There is no useful information in this fallow up.
Barry |
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SteveB
Guest
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| Posted: Thu Oct 25, 2007 2:51 pm Post subject: Re: hvac question |
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"Pete C." <aux3.DOH.4@snet.net> wrote in message
news:47209752.37A26005@snet.net...
| Quote: | SteveB wrote:
"Pete C." <aux3.DOH.4@snet.net> wrote in message
news:471F7F39.D3A3CD2F@snet.net...
SteveB wrote:
I got three bids for an ac unit, all using the same unit. One was for
$4,100 and one was for $6,100 and one was for $7500.
Which one should I take? I'm so confused, and as a consumer, I'm so
stupid
I shouldn't have a driver's license.
I guess I had better take the highest bid as that will insure I get
the
best
job, right? Will the most expensive bubba have the biggest and best
butt
crack? Will I be expected to perform any other sexual favors other
than
bending over to pay the bill?
Any help would be better than being clueless.
Any hvac people out there?
What explains the big difference in price other than the people have a
different image of themselves and a different idea of just how stupid
they
KNOW I am?
Steve
This is a new install at the cabin? The "unit" may be the same, but how
about the ancillary system components like the air handler, ducting,
etc.? Those components could account for a decent chunk of the
difference.
All three bids for the same site. Done from the blueprints and partially
framed house.
Steve
That doesn't mean much. You indicate all three bids are for the
identical A/C "unit", which I believe would consist of the outdoor
condenser unit and the indoor evaporator "A" coil. I don't believe the
"unit" includes the indoor air handler that the "A" coil would be
installed in, nor the ducting, filters, thermostat, etc. and the three
bids could be specing different brands and qualities for those
components.
If you can get a full materials list to go with each bid then you can
see if they really are covering such a wide cost range for truly
identical equipment. Offhand I'd be most leery of the low bid since the
other two are relatively close together. Of course it could be that the
low bid happens to have materials on hand from a canceled order and just
wants to get rid of them. Could be that the higher bidders have all
company employees with benefits to cover, while the low bid is one guy
who hires a sub to install the ducting and has lower overhead. You
simply have to get really detailed specs to properly compare the bids.
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And when you've done that and feel that all three are going to do the same
work with the same equipment and achieve the same result, from there, it's
just how much profit margin they want.
I went through this recently on a metal building. The prices ran from $41
to $65 k for what I specified. Same thickness materials, same number doors,
windows, skylights, etc. A $24k spread is easily explainable. To me,
anyway.
I have decided to do the job myself.
Steve |
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