2.5 TON CONDENSING ,3 TON EVAP

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  #1  
Old 04-22-01, 08:14 AM
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Question

CAN YOU MAKE A 2.5 TON OUTSIDE UNIT WORK WITH A 3 TON EVAP COIL DO I NEED TO CHANGE THE PISTON KIT AND IF I DO WHAT SIZE DO I NEED , THANKS MARK
 
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  #2  
Old 04-22-01, 10:34 AM
fjrachel
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Yes you can. It is a common practice. It raises the SEER slightly and humidity removal is increased. Change the piston. A three ton piston will give you a lower head pressure, which can cause problems on lower temp/high humidity days. Your condenser should come with the correct piston for it. An average 3t piston is about .072. You can make your things even better by installing a TXV valve using a subcooling temp of 10 to 12 degrees.
 
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Old 04-22-01, 01:29 PM
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Question 3 TON EVAP AND A 2.5 TON COND UNIT

I DO NOT HAVE THA CORRECT PISTON TO CONVERT THE 3 TON EVAP COIL TO WORK WITH THE 2.5 TON COND UNIT. WHAT SIZE PISTON KIT SHOULD I GET? HERS THE PROBLEM , I INSTALLED A 3 TON EVAP COIL ON 2.5 TON COND UNIT AND VACUMED IT DOWN , AND CHARGED IT UP AND IT IS STILL NOT COOLING AND THE LOW SIDE KEEPS JUMPING UP TO 90. THAT IS WHEN I SAW THAT YOU HAVE TO MATCH UP THE PISTON KIT TO THE COND UNIT BUT I DO NOT KNOW WITCH ONE TO GET I HAVE A CONVERSION CHART BUT I DO NOT KNOW WHAT SIZE PISTON IS IN THE COND UNIT . THE ONE IN THE EVAP COIL RIGHT NOW IS B17898-65 , WITCH I THINK THAT MIGHT BE TO LARGE, THANKS FOR YOUR HELP ,MARK
 
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Old 04-22-01, 03:47 PM
fjrachel
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B17898-65(65=piston size .065) is a Goodman piston number for a 2.5 ton condenser. A B17898-71(.071) is their 3.0 ton condenser. Your piston is sized correctly. If this is a straight condenser(not a HP), sounds as though you got an inefficient compressor. If HP you may have a bleeding RV.
High suction/low head are classic syptoms of bad valves in a compressor. Check you compression ratio it should be about 3:1.

[Edited by fjrachel on 04-22-01 at 08:33]
 
  #5  
Old 04-22-01, 07:14 PM
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Angry york condensing unit

The York 2.5 ton condensing unit is only 2.5 years old. It is not a heat pump. How do i test the compression ratio to get 3:1? The unit was cooling good before I put the bigger evap coil. The old one just had a leak. So could it also be the compressor? Thanks, Mark!
 
  #6  
Old 04-22-01, 07:39 PM
fjrachel
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If it was cooling before... Have you physically pulled the piston? And actually looked at the size? If not, do.. If it's too big you should be showing a negitive superheat. And compression ratio is head pressure PSIA=suction pressurePSIA. Check that superheat.....Have you ever done this before? And are you certified to handle refrigerant?
 
  #7  
Old 04-23-01, 03:39 AM
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3-ton Evap. with 2.5 ton Cond.

Hi,

If experienced and EPA certified for handling refrigerants,I would do the following:

1-Check Discharge/Head Pressure
2-Check Suction Pressure
3-Check Superheat (Evaporator and Total)
4-Check Subcooling
5-Check Amps (Compressor and Total)

Post these and we'll have a better understanding of unit operation as it is at this time.

Is it possible that you could of had a Liquid Line Restriction and thinking it was undercharged,kept pumping refrigerant trying to raise Suction/Head Pressure and now it is overcharged?

Inefficient Compressor = Low Head Press.,High Suction Pressure,High Superheat,High Subcooling and Low Amps.

Liquid Restriction = Low Head,Low Suction,High Superheat,High Subcooling and Low Amps.

Overcharge = High Head,High Suction,Low Superheat,High Subcooling and High Amps.

Hope this helps.Take Care.

CoolBreeze
 
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Old 04-23-01, 02:46 PM
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Thumbs up 2.5 ton condensing unit

HEY , GUYS , THANKS FOR ALL YOUR HELP ON MY UNIT PROBLEM . I FOUND A BLOCKAGE IN THE CAP TUBES . I CLEANED IT AND VACUMED IT DOWN AND CHARGED IT UP , IT IS COOLING LIKE DREAM, THANKS FOR ALL YOUR HELP , AND I DO HAVE EPA CERTIFICATION , MARK
 
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Old 04-23-01, 03:50 PM
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Cap Tube Blockage

Hi,

Glad you got her cooling. Always remember if the suction won't seem to rise when charging after install/change-out,check for restriction before pumping more refrigerant into it,otherwise,more often than not,you'll still be restricted plus overcharged.Take Care and Good Job.

CoolBreeze
 
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