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Subject Author Date
Is Measuring Superheat at Compressor of Any Value? Ken Hall 07-24-2006
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Posted by Bob_Loblaw on July 24, 2006, 10:58 pm
gofish@gonefishin.net wrote

> In order to effectively troubleshoot your system over the internet we
> will need from you the following:
>
> air inlet & outlet temps at the evap
> suction line pressure
> suction line temp near the evap
> suction line temp near the compressor
>
> air inlet & outlet temps at the condenser
> liquid line pressure
> liquid line temp near the condenser outlet
> liquid line temp near the metering device

What's your girlfriend look like?
Is she a blonde?
Does the carpet match the drapes?
Is she home alone now?
Is she a goer? Wink, wink, nudge, nudge, know what I mean, know what I
mean......?


--
Respectfully, Bob

AppliancePartsPros.com, Inc.
Posted by Friendly Bubba on July 25, 2006, 9:23 am
Ken Hall wrote:
> Another way of asking this is how much is a typical difference in the
> evaporator superheat and the condenser superheat in a split unit? The
> suction line is about 30 feet long.

see if this helps
http://www.hvacloads.com/talkpdf/troubleshooting_with_superheat.pdf




Posted by Ken Hall on July 25, 2006, 12:38 pm
wrote:

>Ken Hall wrote:
>> Another way of asking this is how much is a typical difference in the
>> evaporator superheat and the condenser superheat in a split unit? The
>> suction line is about 30 feet long.
>
>see if this helps
>http://www.hvacloads.com/talkpdf/troubleshooting_with_superheat.pdf

Thanks. This seems to say it's not over charged and may in fact be a
little undercharged.

-- Ken

Posted by Stormin Mormon on July 25, 2006, 5:10 pm
10 degree superheat, and sweating bck to the compressor? Undercharge?
Huh?

--

Christopher A. Young
You can't shout down a troll.
You have to starve them.
.

wrote:

>Ken Hall wrote:
>> Another way of asking this is how much is a typical difference in
the
>> evaporator superheat and the condenser superheat in a split unit?
The
>> suction line is about 30 feet long.
>
>see if this helps
>http://www.hvacloads.com/talkpdf/troubleshooting_with_superheat.pdf

Thanks. This seems to say it's not over charged and may in fact be a
little undercharged.

-- Ken



Posted by Stormin Mormon on July 27, 2006, 7:27 am
see if this helps
http://www.hvacloads.com/talkpdf/troubleshooting_with_superheat.pdf

TROUBLESHOOTING THE REFRIGERANT
SYSTEM
WITH SUPERHEAT & SUBCOOLING
(For those who need a refresher on what superheat & subcooling are,
read the article,
Superheat & Subcooling Made Easy, also in the “For Your Interest”
section)
· Troubleshooting is a matter of temperature differences.
o Superheat is a temperature differential
o Subcooling is a temperature differential
o Evaporator entering air versus leaving air temperature is a
differential.
o Condenser entering air versus leaving air temperature is a
differential.
o These four temperature differentials are the critical
measurements used to determine all refrigerant related
problems. Often a manifold gauge set is not even necessary.
· Critical Temperature Differentials
o Air temperature drop over the evaporator should not exceed 20
degrees F.
o Air temperature rise over the condenser should not exceed 30
degrees F.
o The low side superheat should be between 20 and 30 degrees.
o The condenser subcooling should not exceed 15 degrees.
· An air temperature drop over the evaporator greater than 20 degrees
indicates low evaporator airflow.
· An air temperature rise over the condenser greater than 30 degrees
indicates low condenser airflow.
· A low side superheat less than 20 degrees indicates too much liquid
refrigerant is in the low side.
· A low side superheat greater than 30 degrees indicates too little
refrigerant is in the low side.
· A condenser subcooling exceeding 15 degrees indicates too much
liquid refrigerant is in the high side.
· Comparing these readings will lead to an understanding of what is
wrong with the system. For example, assuming adequate airflow over
both the evaporator and condenser the following is true.
o High superheat with high condenser subcooling indicates a
restriction. Too much liquid is in the high side and too little in
the low side.
o Low superheat with high subcooling indicates an overcharge.
Too much liquid on both sides.
o High superheat with low condenser subcooling indicates an
undercharge. Not enough liquid on either side.
Low side superheat and condenser subcooling simply tell us where the
refrigerant is
located. Too much refrigerant on the high side and too little on the
low side indicates a
restriction. Too much on both sides indicates an overcharge and not
enough on either
side indicates an undercharge.
Norm Christopherson is an HVAC seminar speaker, author and consultant.
He can be
reached at nchristo

at juno.com



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