My Compressor A.B.U. (All Blowed Up)

[Chris Peters]

I couldn't stand looking at this thing any more, I had to cut it open.  Here's some pics.  On top is a big ass motor.  It looks like there are 2 sets of windings offset 90 degrees.  These are in pairs opposite each other.  The inner winding on one side near the top is shorted and severly overheated.  The bottom is not as bad but still obviously got hot.  In the bottom part you see the armature of the motor sticking up and the compressor is below.  I will get there later but it seems to turn both directions smoothly and easily.  I can hear a faint click when you turn clockwise, must be the 2nd cylinder engaging.  We'll get there later.  So it looks to be purely electrical failure, whether it occurred on start or while it was running, or was it a while in the making?  Before opening, I was shorted between R and the outer housing.  Any ideas??

[Chris]

I just watched the life test video on youtube. If you only run for 3
seconds the system barely builds pressure. What makes it harder for
the compressor to start is the pressure DIFFERENTIAL between the
suction and and outlet pressures of the compressor. Before starting
at 91 degrees ambient temp your gauge pressures are about 280 psi on
the suction and 330 on the outlet. This is 50 psi differential, not
300. If the system were to be allowed to run until full pressure is
achieved, you would have somewhere around 150 psi suction and 400
outlet, probably even more differential at 91 degrees. When I let my
system sit for 2 minutes, I see about 200 psi suction and 350 outlet
psi. This is 150 psi differential. Could you make another video to
show your system starting in a more normal operation? If you really
wanted to torture test, try reaching full pressures then restart after
less than 2 minutes, say 30 seconds. It takes my system at least 30
to 40 seconds to reach full pressure from equilization in 1cyl mode.
The way you are testing the compressor is starting at near
equilization, as if you had used the solenoid bristol suggested to
dump the pressure differential before starting. You could probably
start this way with an even smaller condenser. I don't believe this
accurately simulates real life, nor is it a torture test, it is about
the easiest this compressor could be started.

[MICHAEL BARRICK]

i agree it also needs tested in sub zero conditions or at lest below 25 degrees with booster starting

[one mad dealer]

I'm not sure either of you are getting what it is that I am doing or
why.

1st- I already know the max head pressure and differential cylinder 1
and cylinder 2 can start into with a smaller cap. This is the first
thing I needed to determine. I also know what pressures the system
drops to after the minimum 2 minute delay on a 70 degree day and a 100
degree day. I'm proving that the UMSR and start cap hold up with no
failure and I'm starting into head pressure! I'm not waiting for the
system to drop down to idle pressure.

2nd- I'm proving that the UMSR drops the cap even after a few THOUSAND
starts do it DOESN'T cook the motor or caps. The dual potential relay
setup caused frequent start and run cap failure. How is this not a
torture test? Is your system restarting quickly after shutting down?
If I wait the 2 minute delay before restarting even after a 10 minute
run cycle, what am I proving? If the condenser fan and indoor blower.

3rd- Pressures are lower when it is colder, not higher!?! Why would
it be harder to start when its cold? The crank case heater is there
so it is not harder to start when its cold out.

Hope this clarifies what I'm doing and why.

Gabe



On Jul 26, 6:00 am, MICHAEL BARRICK

> the easiest this compressor could be started.- Hide quoted text -
>
> - Show quoted text -

[Chris]

You clearly claim you are starting the compressor into 300 psi, this
is a misrepresentation. If the pressure is equal on both sides you
are starting into 0 psi. Your gauges clealy show a max of 50 psi
differential, this is a small amount. If you have already determined
the max pressure you can start with your capacitor selection would you
please share this information?
The crankcase heater has no effect on ease of starting. It is there
to ensure no liquid refrigerant is mixed in with the crankcase oil
that would dilute the oil. Do you not understand how this works or
are you intentionally misleading us?

Those of you following the Pied Piper should practice critical
thinking skills, you are the ones doing the torture test.

[one mad dealer]

"Crankcase heaters offers critical compressor protection. They keep
the crankcase warm while the compressor is in an off cycle; an
important step in minimizing refrigerant migration to the compressor.
The crankcase heater is designed to keep the refrigerant at a
temperature higher than the coldest part of the system."
"Outdoor and rooftop units exposed to cold winter winds can become so
viscous that the compressor cannot develop oil pressure. That’s why
compressor manufacturers recommends the use of crankcase heaters on
all
refrigeration systems in which the compressor is exposed to cold
ambient temperatures – to keep the oil warm enough to remain fluid."

Constantly going out of your way to insult people rather than have an
intelligent conversation is going to leave you working on this system
by yourself. I'm guessing that your local HVAC guys won't help you,
and I'm sure you think it because you have an Acadia. You obviously
can read Wikipedia or whatever else a search brings up, but I highly
doubt you have any sort of refrigeration training that makes you an
expert on the topic. I would be happy to share my results with anyone
BUT you since you clearly know it all and my testing is worthless.
You are more than welcome to get capacitors and gauges and see for
yourself what the compressor does under different pressures and
temperatures. Have fun!

Gabe

[Hing Lum]

As a reader of this group and a non-technical person, I very much appreciate everyone sharing their knowledge and problems (especially with me). Back in February, I had no heating system with 3 units down and out and the installer not willing to come to my assistance after taking my money to look at the units.  By reading everyone's comments and insights, I got the courage to open the panel and look into the heat pump and learned (a little of) what make them tick. And with the knowledge gained by reading and watching the videos, especially from Gabe and David who actually started this idea of trying to find a solution for us who were down and out, I actually have 2 of 3 units working now and the 3rd one will be hooked up soon. I will have heat for my family this winter and not have to blow another $35,000.  Much appreciation to all, especially Gabe and David, for your help.

[Dave]

I agree, without Gabe & David many of us would have given up and replaced the system . I recommend any one interested in maintaining their Acadia to join savemyacadia.org  the idea here is to help each other out not find fault with each other.

Sent from my iPad

[one mad dealer]

Sorry, I should have made it clear that my comments were directed at
Chris Peters. Everyone else seems to genuinely appreciate what David
and I are trying to do.

Gabe

On Jul 26, 1:19 pm, Dave <wolfe4...@gmail.com> wrote:
> I agree, without Gabe & David many of us would have given up and replaced the system . I recommend any one interested in maintaining their Acadia to join savemyacadia.org  the idea here is to help each other out not find fault with each other.
>
> Sent from my iPad
>

> On Jul 26, 2011, at 12:36 PM, Hing Lum <bestrealestat...@gmail.com> wrote:
>
>
>
> > As a reader of this group and a non-technical person, I very much appreciate everyone sharing their knowledge and problems (especially with me). Back in February, I had no heating system with 3 units down and out and the installer not willing to come to my assistance after taking my money to look at the units.  By reading everyone's comments and insights, I got the courage to open the panel and look into the heat pump and learned (a little of) what make them tick. And with the knowledge gained by reading and watching the videos, especially from Gabe and David who actually started this idea of trying to find a solution for us who were down and out, I actually have 2 of 3 units working now and the 3rd one will be hooked up soon. I will have heat for my family this winter and not have to blow another $35,000.  Much appreciation to all, especially Gabe and David, for your help.
>

> > > thinking skills, you are the ones doing the torture test.- Hide quoted text -

[Chris]

I'm sure I'm wrong again but... Didn't Chip tell David part of the
problem was due to the motor supply side of the contactor was wearing
faster than the low current potential relay side causing the contactor
to tip resulting in a bad connection across the contacts? If you use
one umsr50 in place of the 2 potential relays, won't your 2 pole
contactor have the same problem, you are not using one side at all
now? I seem to recall hearing that contactor wear is a normal
function to keep the contacts clean.


Ò Bristol
Compressors, Inc. Number: 135
Application Bulletin
CRANKCASE HEATERS
Release EN Number F03602 Release Date 2/27/98
REVISIONS
Application Bulletin 135 - Page 2 of 5
Revision F03602
Bristol Compressors, Inc.
â
Application Bulletin
No. 135 Release E/N: F03602
Date: 2/27/98
Revision E/N: F03602
Date: 2/27/98
Subject: Crankcase Heaters
1.0 Purpose
To inform the customer of the following:
¨ Importance of a crankcase heater and the need for system evaluation
to assure necessity
and proper sizing of the heater for each application.
¨ Compressor charge limitation.
¨ Systems exceeding the compressor charge limitation.
¨ High and low ambient liquid refrigerant migration and methods to
correct.
¨ Important factors and test procedures to determine need and/or
sizing of a crankcase
heater.
2.0 Crankcase Heater Importance and Sizing
A crankcase heater, correctly sized and energized for the minimum
required length of time, will
minimize the condensing of refrigerant in the compressor and increase
the longevity of the
compressor bearings and other critical components. When a system has
been off – new system
start-up or out-of-service condition which de-energizes the crankcase
heater for at least 18 to 24
hours, the system is thermally soaked out. This means all system
components, including the
condensed refrigerant, are at a stable temperature and pressure and
vary only as the ambient
changes. When this occurs, refrigerant has migrated to the compressor
sump and saturated the
volume in the cylinders, cylinder head, shock loop, and discharge
muffler with a mixture of
refrigerant and oil. If the compressor is started in this condition,
liquid slugging will occur. To
prevent this abusive slugging, a temperature difference (DT) must be
maintained between the
sump of the compressor and the coolest point in the system. For the
best safety margin, the
compressor sump must be maintained at least 20°F warmer than the
coolest section of the system,
only if this section(s) can hold the system charge. If the “coolest
section” does not have the
volume to hold the system charge, the sump needs to be 20°F above the
warmest section of the
system. Please note that certain applications may require a 30°F DT,
and system tests are needed
Application Bulletin 135 - Page 3 of 5
Revision F03602
to assure adequate DT under the worst case conditions expected. At
ambients of 20°F and lower,
refrigerant will migrate out of the compressor when a 5°F DT is
maintained.
NOTE: Some users have a misconception that a properly sized crankcase
heater
will protect the compressor under all circumstances. If the system
loses
compressor suction superheat to a point that the heat output of the
crankcase
heater cannot maintain the sump DT, refrigerant can migrate to the
compressor
sump. Optimum crankcase heater operation requires the following
compressor
superheats to be maintained (refer to Application Bulletin 121) –
suction = 5°F
minimum, sump over saturated suction = 30°F, discharge = 50°F minimum.
The crankcase heater size (in watts) depends on the following factors:
¨ Differential temperature (between compressor sump and system) which
is necessary to
move/keep liquid refrigerant out of the compressor.
¨ Total system charge and potential overcharge.
¨ Time the heater is energized before compressor starts up.
¨ Maximum system ambient (indoor section and outdoor section).
¨ Sun load on condenser (louvered, covered or exposed coil).
¨ Type of system: split, package, air conditioning, heat pump,
chiller, close coupled, long
line sets, etc.
¨ CFM of air across compressor.
¨ Type/location of heater – in well or wrap around.
Since the above factors are dependent on system design, it is critical
to evaluate the
heater in each application.
3.0 Charge Limitation
The “compressor charge limitation” is published on the individual
specification summary sheet for
each compressor. If the total system charge is below this amount, and
the compressor superheats
are maintained within our Application Bulletin 121, most applications
will not need a crankcase
heater. However, there could be circumstances (defrost mode on heat
pumps, hot water heating
cycle that switches into the cooling or heating cycle on the fly,
harvest cycle on ice machines, etc.)
where “at or below” charge limit levels could reduce the compressor
life unless proper refrigerant
control and system controls/protection are utilized.
4.0 Systems Exceeding the Compressor Charge Limitation
These systems require a crankcase heater and may require a pump down
scheme or accumulator
to prevent flooded starts (refer to individual product bulletins for
required testing and to Application
Bulletin 101 on accumulators/refrigerant control. These precautions
are necessary since refrigerant
can collect in the suction line or evaporator during the off-cycle,
returning to the compressor as a
solid liquid column, with extreme velocity, on start-up. The velocity
and the weight of the liquid
slug(s) may be of sufficient magnitude to override any anti-slug
protection devices designed within
the compressor.
Application Bulletin 135 - Page 4 of 5
Revision F03602
5.0 Refrigerant Migration
Defined as the movement of refrigerant from one system component to
another due to the
temperature/pressure difference (DP) between those components.
5.1 High Ambients
If crankcase heater wattage is inadequate, high ambient temperatures
(greater than or equal
to 80°F) coupled with high solar load on the system condenser coil (no
louvers) can cause
refrigerant to migrate out of the condenser, in reverse, back into the
discharge line through
the compressor valves to the lowest temperature area of the system.
During this reverse
migration, refrigerant can liquefy in the cylinders of the compressor
which can result in a
start-up slug. To minimize this effect, the crankcase heater needs to
maintain the sump at
least 20°F above the highest temperature in the system.
Other wide differential temperature circumstances to consider are:
¨ Building under construction, i.e., no cooling (evaporator warmer
than condenser). Also
see Ground Source Heat Pumps (Application Bulletin 134).
¨ A split system evaporator is normally in a cooler location, while a
rooftop package
system evaporator is in a much hotter location and could be even
hotter than the
condenser on initial start-up and after extended shut-down periods.
This condition can
allow refrigerant to fill the vital parts of the compressor, resulting
in a start-up slug even if
the system charge is within the published limitation.
5.2 Low Ambients
At low ambients (less than or equal to 60°F) and low condenser solar
load, refrigerant can
migrate from the evaporator through the compressor to the condenser.
Again, refrigerant will
tend to liquefy in the cylinders of the compressor. The crankcase
heater needs only to
maintain the sump at least 5°F above the lowest temperature in the
system to minimize the
effect. The lower ambient will allow refrigerant to flow out of the
compressor at a faster rate
than at the higher ambient.
6.0 The Following is a Recommended Test Procedure to Confirm if a
Crankcase Heater
is needed and/or Properly Sized
Heaters are normally sized to move refrigerant out of the compressor
in 12 to 24 hours. This time
allotment is suggested in order to allow the effects of sun exposure
(approximately 720 BTU’s of
heat per square foot of exposed coil - no louvers - to the system) to
be minimal at some time
during the compressor off period. Large compressors will be equipped
with sight glasses which
can be used to see when enough refrigerant has moved out of the sump
to create a safe level. The
best assurance is to never let the compressor sump be the location of
the lowest temperature
component in the system.
¨ Install compressor or system in a controlled environment room,
capable of controlling the
condensing unit and evaporator at the highest and lowest (worst case)
ambient they will be
subjected to in the field within a 24-hour period. (Package systems
should be tested with the
evaporator and condenser sections at the expected worst case
temperature.)
Application Bulletin 135 - Page 5 of 5
Revision F03602
¨ Compressor weight to be monitored with scales and equipped with
sight tube and/or sight glass
mounted on compressor at normal oil level.
¨ Double-sided sight glasses should be installed in suction and
discharge line of system to confirm
if liquid is returning to compressor at any time.
¨ Connect the condenser and evaporator to the compressor (or
equivalent containers equal to
the volume in the system).
¨ Use flexible lines to connect compressor to system or container
(not needed when using sight
tube or sight glass mounted on compressor).
¨ Evacuate the system.
¨ Record weight of the compressor.
¨ Charge the system to its normal refrigerant charge level.
¨ After the environment temperature is set, allow system to soak-out
for 24 hours.
¨ Record the weight of compressor after 24 hours.
¨ Energize the crankcase heater.
¨ Record weight of compressor at least every hour.
¨ Crankcase heaters are normally sized to remove all liquid
refrigerant from compressor in 24
hours or less. Testing for 12 hours of total test time at the night
time temperatures, or for the
number of hours the system will be at lower temperatures, will be a
determining factor in sizing
the heater.
¨ If refrigerant remains in the compressor sump after the recommended
removal time, the
wattage of the crankcase heater will need to be increased or system
modifications made to
improve the removal rate.
7.0 Test Compressor Availability
Compressors with a sight glass or sight tube are available and
recommended for test. They will
allow visual monitoring of the amount of refrigerant being moved out
of the compressor throughout
the test.

[MICHAEL BARRICK]

i just had a compressorfailure it would noy pump down in vacuum when pumping down that is a sign of valve failure it is 2 years old all start componits look good not burnt

[David Friedman]

Since in the new circuit - the second contact is not used - the fact that it becomes high resistance is of no concern - it is not in the circuit.  The only contacts used are the power contacts and they holds up just fine. In fact my Acadia still is running witht the original GE contactors that had failed. (both of the    right side contacts on PR-1 and PR-2 went open on my system causing    the compressor to not run at all - but to draw high current using the big start cap engaging the Bristol overload. The only thing that saved my compressor was the fact that the Bristol overload worked and I shut my system down as soon as I realized that stage two (which failed first) didn't run the compressor at all.  It just clunked and then went dead based on the cutout working.

 

In terms of wiring  - one could wire the pair of contacts using the second contact to make and break the motor connnection to L2 as is done with the booster contactor.  In this case both contacts carry power and this in fact might be a better solution for contactor life.

 

Do you intend to use the USMR solution to prevent electrical failure on your new compressor. From your comment is seems as if you might not know how it is hooked up avoiding the original contact problem.

David

[David Friedman]

Repetitive cycle testing is done using a low differential - but as
we have discussed before - the electrical load on the motor is quite
independent of actual torque load. If the starting torque is ample
the motor spins up very quickly and the power slug from starting is
dominated by the start component values.
Our initial testing started with the same fact that you quote - namely
that the differential which determines torque required - is about
150. We chose a cap value that started well into a 200 psi
differential. ( a value that gives margin for low voltage starts
using theoretical considerations of lowered torque with lowered
voltage ) and then we shifted to a test routine that gave us very
fast restarts (just slow enough not to burn up the start cap due to
unusual duty cycle starting)

Our repetitive cycle testing at low differential stresses the
electrical components and proves high reliablility of the start
components - and is not a repetitive test of ability to exceed the
"after 2 minute delay" differential requirement.

Also - the issue of "builds pressure" is not simple. When the system
starts from zero pressure I would guess that intitally the
differential is just the head pressure unitil pressure builds up at
the suction side. The important number is the differential after high
head pressure has been built and system has been cooling/heating for a
while, and then bleeds down during off time to the 150 we both are
assuming is a good number for start requirements. Any insites you have
as to that reguired start differential would be helpful.

David Friedman

[khei...@myfairpoint.net]

Welcome to my world.
I said , Fu&k it and replaced it with the Goodman condenser. I have a
court case awaiting trial in Milford NH. What state are you in?
I may be able to make you the correct compressor. Let me know.
Kris Heikkila

> > I just watched the life test video on youtube.  If you only run for 3
> > seconds the system barely builds pressure.  What makes it harder for
> > the compressor to start is the pressure DIFFERENTIAL between the
> > suction and and outlet pressures of the compressor.  Before starting
> > at 91 degrees ambient temp your gauge pressures are about 280 psi on
> > the suction and 330 on the outlet.  This is 50 psi differential, not
> > 300.  If the system were to be allowed to run until full pressure is
> > achieved, you would have somewhere around 150 psi suction and 400
> > outlet, probably even more differential at 91 degrees.  When I let my
> > system sit for 2 minutes, I see about 200 psi suction and 350 outlet
> > psi.  This is 150 psi differential.  Could you make another video to
> > show your system starting in a more normal operation?  If you really
> > wanted to torture test, try reaching full pressures then restart after
> > less than 2 minutes, say 30 seconds.  It takes my system at least 30
> > to 40 seconds to reach full pressure from equilization in 1cyl mode.
> > The way you are testing the compressor is starting at near
> > equilization, as if you had used the solenoid bristol suggested to
> > dump the pressure differential before starting.  You could probably
> > start this way with an even smaller condenser.  I don't believe this
> > accurately simulates real life, nor is it a torture test, it is about

[one mad dealer]

Michael,
Were you pumping down a system to replace it? Or to work on the
refrigeration circuit? At what psi did you see this happen?

Gabe

> > > - Show quoted text -- Hide quoted text -

[MICHAEL BARRICK]

for service it stopped pumping down at 30 psi the owner said it would not cool as well all of the time some times it would raise the temp 3 to 4 degrees before it would cool and some times it did notkeep up this is the first time in 3 threes

[one mad dealer]

Pull out the 410a and see if you don't pull out a full charge. Sure
its not going off on a pressure switch?

Gabe

On Jul 27, 9:54 pm, MICHAEL BARRICK

[Chris]

You forgot to start by insulting me. Actually, your idea of running
the motor common thru the unused contacts of the pri1 and pri2
contactor could be a good solution, or how about using single pole
contactors? We agree that there is an issue with the original
contactor circuit design with the high and low current contacts, but I
am not sure of which side caused the problem, maybe either side could
be an issue. If the contact tips it could just as well cause a poor
connection across the motor high current contact causing low voltage
to the run windings. Might this even cause the motor to slow or stall
after it starts and the relay opens causing the potential relays to
cycle on and off repeatedly?

As for compressor starting pressure differential, you remarked:

"When the system starts from zero pressure I would guess that
intitally the
differential is just the head pressure unitil pressure builds up at
the suction side."

When the compressor is off, with r410a, at say 68 deg F, the system
pressure is about 200 psi evenly through out the system, the pressure
is equal on both sides, there is 0 pressure differential even though
the system is at 200 psi. When the compressor starts, it sucks
refrigerant from the low or suction side and pumps it out into the
outlet, high side. The pressure on the low side drops and rises on
the high side. When cooling the indoor txv tries to regulate the temp
around 38 degrees or so, the low side would be around 115 psi, and the
high side, depending on system load may be somewhere around 400 or
more psi. Here the differential would be 400 - 115 = 285 psi. Head
pressure isn't a real good term, it could refer to the output or high
side pressure, or the pressure differential, depending on how it is
used and by who. Good terms would be low or high, suction, outlet and
differential. After the compressor shuts off, the pressure very
slowly bleeds down towards equilization pressure. The txv's used are
non bleed type, for increased efficiency, they try to retain the
pressure differential while shut off. I have seen about 150 psi
differential after 2 minutes of compressor off. I have no idea what
the differential may be in winter in heat mode. I have never seen the
operating pressures until I replaced my compressor last week, so
heating operation is unknown to me.

I will be trying the umsr, for now I am using the new siemans
contactors, caps and relays I got with the compressor. I am still
working on my delay system and a way to document starting and run
current along with input and start winding voltages against time. I
have installed 2 pressure transducers that give me an instant voltage
reading for system pressures so I can chart current, voltages,
pressures and time for real comparison both with and without pressure
equilization thru the solenoid and check valve connecting my primary
compressor inlet and outlet with different starting systems. Together
with the compressor I had to replace, the new plumbing cost me less
than $100 and was relatively simple to install.
When I have sufficient data, I wil share it with the group

[one mad dealer]

Chris,
Its funny, now that you have your system running again you are looking
for advise from the same people who you frequently insult... Odd...
You'll happily use the UMSR, but you go out of your way to tell
everyone that they should contact the manufacturer so they don't have
to compensate us for our work and testing. You claim that you had a
compressor shorted to ground, but yet you stated that it starts??? I
really hope you re-think your approch and show a little respect for
those who have decided to help since it was not our responsibility to
do so.

Gabe

[Chris]

You seem to forget who first found the umsr. If I had not brought it
up you two would still be touting the kickstart as the answer. I'm
not looking for your advice, I am pointing out inaccuracy for those
who may not see it. If my info is not wanted this will be my final
post. Good luck everyone!

-

[Chris]

PS. Remember the single pole contactor was my idea too when you start
selling them.