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  1. #1
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    CVHE Purge Unit Temps?

    Can someone please explain to me the operation of the purge unit. Still kind of new with chillers. I get what the purge's purpose is, but still have a few unanswered questions.

    Does the Filter Core house just water? Or water and refrigerant?

    How does one know whether there is water in it? I see the sightglass, but don't know if that's liquid refer or water.

    How does one go about draining the water in the purge unit?

    Why does my liquid temp stay at 70deg F and my suction continue to steadily drop until there is a bit of frost on the compressor suction side?

    Should the Filter core container be pressurized, because when I press the depressor on it, all that comes out is an alcohol watery looking substance with no pressure behind it? I have to physically pull out the schrader valve in order for it to stop leaking the watery substance.

    I know the purge unit is supposed to pump air/water out of the chiller. If it is pumping air out, will the sightglass bubble?

    How do I know if the purge unit is pumping out either air or water?

  2. #2
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    Quote Originally Posted by ZeroTolerance View Post
    Can someone please explain to me the operation of the purge unit. Still kind of new with chillers. I get what the purge's purpose is, but still have a few unanswered questions.

    Does the Filter Core house just water? Or water and refrigerant?
    It houses refrigerant. However, if that refrigerant has water in it, it will absorb that water from the refrigerant.
    How does one know whether there is water in it? I see the sightglass, but don't know if that's liquid refer or water.
    What style purge do you have? If sightglass is on the purge tank, the water will float on top of the liquid refrigerant-you may be able to see it. If sightglass is in liquid return line-moisture indicator in the glass will indicate the presence of water.
    How does one go about draining the water in the purge unit?
    Crack open the 1/4 inch service valve on the the purge tank while the chiller is running with a positive condenser pressure-it has a diptube that extends down to the liquid level. I have rarely used this myself. If there is water, change the drier.
    Why does my liquid temp stay at 70deg F and my suction continue to steadily drop until there is a bit of frost on the compressor suction side?
    "Liquid Temp" is saturated temperature of the chiller refrigerant in the chiller condenser (or possibly chiller evaporator). Purge compressor suction temps are a function of load on the purge tank (which functions as purge cicuit's evaporator); air will displace the load and result in low suction temps, which should initiate a pumpout cycle.
    Should the Filter core container be pressurized, because when I press the depressor on it, all that comes out is an alcohol watery looking substance with no pressure behind it? I have to physically pull out the schrader valve in order for it to stop leaking the watery substance.
    [COLOR="Red"]The filter drier is at chiller condenser pressure. There may be a slight difference, but not enough to see on your gauges[COLOR="Red"]
    I know the purge unit is supposed to pump air/water out of the chiller. If it is pumping air out, will the sightglass bubble?
    It pumps out air, not water. Sometimes bubbles will be seen due to the relatively warm temp of the sightglass housing "boiling" the refrigerant; when pumping out, the pressure in the tank is slightly lowered.
    How do I know if the purge unit is pumping out either air or water?
    It pumps out air. If any liquid is seen to be pumping out there is a problem. Hmmmm.... still trying to get the hang of posting like this...

  3. #3
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    Nucl, I greatly appreciate all of your help. You have been a tremendous source of information in the matters that I haev brought forth.

  4. #4
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    Jan 2005
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    Purifier purge

    Zero Tolerance- Liquid temp is the temperature of the liquid refrigerant being returned to the chiller, if this is a stand alone purge. It will have a 5 X 5 finger pad mounted on the purge itself. If you are controlling the purge through the clear language display on the chiller control panel, then it shows the temperature / pressure of the condenser. Water has to drained from the 1/4" service valve behind the sight glass on the refrigerated heat exchanger. As far as actual suction temperature goes that tells you what your purge is doing. If it is picking up only refrigerant vapor it will be close to your condenser temperature due to superheat action on the coil as the vapor is condensed back to a liquid state. The small refrigeration unit maintains a -10*F to a 5*F supply to the coil inside the heat exchanger and as log as there is only vapor being condensed the latent heat will be high. Once non-condensibles enter the heat exchanger the space to create a change of state is reduced as is the amount of superheat out of the heat exchanger is reduced until it drops to 18*F. Then the pump-out compressor is started and the 2 solenoids open up and pump out the non-condensibles, there is a restricter tee on the inlet of the pump out compressor to prevent the loss of refrigerant. The compressor stays active until the refrigerant compressor suction line temp warms up to 25*F or there about. If you have large amount of air you can by-pass the restricter by putting a short refrigerant hose on the branch of the tee at the pump out compressor and the outlet of the solenoid the tee is connected to, used the cap from the tee on the now open 1/4" flare port. Don't leave it like this overnight as you WILL loose a lot of you charge. Hope this helps a little more with understanding the Trane Purifier Purge. GEO
    Once in a while everything falls into place and I am able to move forward, most of the time it just falls all over the place and I can't go anywhere-GEO

  5. #5
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    Quote Originally Posted by ga1279 View Post
    Zero Tolerance- Liquid temp is the temperature of the liquid refrigerant being returned to the chiller, if this is a stand alone purge. It will have a 5 X 5 finger pad mounted on the purge itself. If you are controlling the purge through the clear language display on the chiller control panel, then it shows the temperature / pressure of the condenser. Water has to drained from the 1/4" service valve behind the sight glass on the refrigerated heat exchanger. As far as actual suction temperature goes that tells you what your purge is doing. If it is picking up only refrigerant vapor it will be close to your condenser temperature due to superheat action on the coil as the vapor is condensed back to a liquid state. The small refrigeration unit maintains a -10*F to a 5*F supply to the coil inside the heat exchanger and as log as there is only vapor being condensed the latent heat will be high. Once non-condensibles enter the heat exchanger the space to create a change of state is reduced as is the amount of superheat out of the heat exchanger is reduced until it drops to 18*F. Then the pump-out compressor is started and the 2 solenoids open up and pump out the non-condensibles, there is a restricter tee on the inlet of the pump out compressor to prevent the loss of refrigerant. The compressor stays active until the refrigerant compressor suction line temp warms up to 25*F or there about. If you have large amount of air you can by-pass the restricter by putting a short refrigerant hose on the branch of the tee at the pump out compressor and the outlet of the solenoid the tee is connected to, used the cap from the tee on the now open 1/4" flare port. Don't leave it like this overnight as you WILL loose a lot of you charge. Hope this helps a little more with understanding the Trane Purifier Purge. GEO
    GEO is correct, if your purge is a Purifier Purge. If your purge is an EarthWise Purge, it will still be using the same principle of operation, but some of the numbers will be different. And there is no bypass available for large amounts of air. The restrictor is larger and already passes more volume than the Purifier Purge restrictor does. Trane says removing (or bypassing) the restrictor on the EarthWise causes the greater loss of refrigerant without providing an appreciable increase of air removable. On another thread you talked about a chiller with CH530. Is this the same one? If the control panel and purge are both original to the chiller, then I believe you have an EarthWise Purge. There is probably a decal on the purge identifying which one it is, too.

  6. #6
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    We have four total chillers.

    This chiller in reference is a 120-ton Trane CVHE from 1984 with the big black box and the four vertical gauges on the left hand side kind of like the 800-ton Trane I was talking about in another one of my threads.

    The 120-ton has a big leak in it, and as of today, we condemned it; as it will be replaced along with our 800-ton in December of this year.

  7. #7
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    Quote Originally Posted by Nuclrchiller View Post
    ...And there is no bypass available for large amounts of air. The restrictor is larger and already passes more volume than the Purifier Purge restrictor does. Trane says removing (or bypassing) the restrictor on the EarthWise causes the greater loss of refrigerant without providing an appreciable increase of air removable...
    there isn't a FACTORY installed bypass. i have bypassed the restrictor in the past on these as well and they will remove much more air than you think...i don't think that they will remove nearly as much refrigerant in bypass mode as the older purges did in bypass mode.
    How to make the perfect "Half-Hitch" knot or any other boyscout knot in 3 easy steps...

    1. Remove your meter leads from the meter and very carefully return them to their storage case or bag.
    2. Wait 2 seconds
    3. Very carefully remove your meter leads from their storage place and enjoy your new knot!

  8. #8
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    I admit I've never had a reason to bypass it and find out. That's why I said "Trane says...". I wonder if you're just pointing out how I misspelled "removal"? BTW Jay, your new sig line confuses me....

  9. #9
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    Quote Originally Posted by Nuclrchiller View Post
    I admit I've never had a reason to bypass it and find out. That's why I said "Trane says...". I wonder if you're just pointing out how I misspelled "removal"? BTW Jay, your new sig line confuses me....
    if i pontd oot evreebuddies miispelllled werds, i wood bee her al dai!

    Song lyrics from Werewolves of London by Warren Zevon
    How to make the perfect "Half-Hitch" knot or any other boyscout knot in 3 easy steps...

    1. Remove your meter leads from the meter and very carefully return them to their storage case or bag.
    2. Wait 2 seconds
    3. Very carefully remove your meter leads from their storage place and enjoy your new knot!

  10. #10
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    I think I remember now. Is that the song that keeps saying "Ah oooooo"? Be glad you're reading that pathetic attempt at singing, and not hearing me try to sing it.

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