Reply35* at the compressor is not that bad!
what is 317 liquid line?
do you have 75# suction or 75* suction line????????
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Changed the oil three times. Oil was nasty. Replaced suction core and liquid line drier. Checked suction screen. Its now running with 50 psi oil diff. Loading and unloading properly ( low voltage was wired wrong). All seems good except high superheat (35*) and low subcool (5*). 74 suction 317 liquid line. I know probably still undercharged, just wanted to let it run a while and check it after space has cooled.
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35* at the compressor is not that bad!
what is 317 liquid line?
do you have 75# suction or 75* suction line????????
true knowledge exists in knowing that you know nothing.
Professional Member*
75# suction line
317# liquid line
Regular Guest
I'm betting on a plugged condenser.
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Originally Posted by socotech
Two TxVs in that AHU or just one ?
I've got an old York 15 ton that splits off into two circuits at the AHU with two solenoid valves.
Sounds undercharged a bit and maybe you're dealing with a lot of load.
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High load (80*). One txv and no solenoid. 100*+ ambient. There is possibly some condenser air recirculation too. It has a solid brick wall on three sides about 20" out.
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Single row condenser coils. They look clean, but I'll be honest....I did not wash them.
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317# head sounds high!
true knowledge exists in knowing that you know nothing.
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Went by and checked it yesterday. Its down to 280#. Its also 98* ambient in the shade.
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317 on a unit that old 98 ambient is actually not that bad.
Does that unit have the mechanical timer ?
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135* SCT
130* LLT
005* SC
079*SLT
044* sst -74# SP
035* SH
HIGH EVAPORATOR TEMPERATURE
130* LIQUID ENTERING EVAPORATOR
HIGH EVAPORATOR CAPACITY
LOW CONDENSER CAPACITY
EXTREMELY LOW NET REFRIGERATION AFFECT
it is clearly low on refrigerant, i would like to see how high the head is after he gets 12 * subcooling?
true knowledge exists in knowing that you know nothing.
Professional Member*
135* SCT
130* LLT
005* SC
079*SLT
044* sst -74# SP
035* SH
HIGH EVAPORATOR TEMPERATURE
130* LIQUID ENTERING EVAPORATOR
HIGH EVAPORATOR CAPACITY
LOW CONDENSER CAPACITY
EXTREMELY LOW NET REFRIGERATION AFFECT
it is clearly low on refrigerant, i would like to see how high the head is after he gets 12 * subcooling?
Lol....
Liquid line is hot because units short charged and what does insuring a liquid seal in the condenser have to do with excessive head pressure. I'm not saying stack the coil with excessive refrigerant.
So it's ok to short charge a system because you're afraid your going to launch the heads off the valve plates ? Charge the thing correctly and then see what your head pressures are.
It's hackery . What does short charging do to a unit ? Lowers capacity, lowers efficiency causing the unit to run longer, can cause icing, poor cooling of the compressor windings, etc.
Ive got an old York 20 ton and a old York 30 ton split ( installed in the late 80s ) with Copelands in them and they're properly charged, running high head ( 325,330 ) and they're still in one piece after 7 years of PMs.
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Yea its got an old camstat timer
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I have never heard the term "short charged". What is that?
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Yep, I've got three just like it. ( two 20s and a 30 )
Old school controls with a choke coil to lower fan speed on the #1 condenser fan motor for capacity control.
One of our EX-technicians wen't out on a service call and destroyed the control wiing inside the panel on the 30 when I was on vacation.
I had to start from scratch to rebuild that panel.
Professional Member*
Purposely under charging a unit to avoid high head trip or extended high head run time. ( I'm not saying you did that I just use the term to describe an undercharged unit in general )
I don't believe in it. These Yorks I have have coils that are 2 pass and in horrible shape.
They are charged to 12 to 14 degrees of subcooling and run fine and that's in Houston.
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Ahhh yes. Short charge. I get it. Thats exactlly what I did. Afraid to blow the head of the compressor through my chest I guess. Learn something new everyday.
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I can understand the hesitancy to charge to correct subcooling when dealing with older coils and units in a hot climate but what will actually happen is your liquid line will cool down and you'll be providing your customer with 100 % of the capacity minus what it's lost because of it's general age.
You will probably be surprised to see your head drop a little.
Also you're Compressor amps will lower as you start cooling your wingdings more efficiently.
I've gotten into a few debates over this with some of our fellow techs.
You are not stacking refrigerant by providing a liquid seal and by providing a solid column of liquid to the TXVs, if your head DOES climb it's because you now have 100% capacity.
Charge it to correct super heat and let it ride. All three of my antique Yorks are charged to 12 to 15 degrees of sub-cooling and ran fine through the heat wave we had last month.
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