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Thread: TXV question

  1. #1
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    Confused TXV question

    I am new to HVAC. I have been trying to purge this system and can not get nitrogen to flow through the entire system. I connect to the high side at the collector and start the the Nitrogen flow and the gauge never rises on the low side.
    I went down inside the cooler box opened the Evaporator and tried to push nitrogen through the TXV and it wouldn't go through. The system has been off for days and everything is at room temperature. Shouldn't the TXV be open and allow Nitrogen to pass?
    I did a Nitrogen pressure test with the manifold connected to both High and low line at 300 psi for 10 hours prior to this. And it held at 300 psi
    I need to purge these lines out somehow because I couldn't get a good vacuum done. I could only get it done to 610 and it would start to rise slowly which tells me I have to get more vapor out. So I changed the oil in my vacuum and let it run for over night. And it was still reading 1200 microns. The day prior I got it down to 610.
    I'm confused about what is happening hear.
    I hope someone will shear their knowledge.

  2. #2
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    Perhaps just break down and hire a contractor. This is not a good starting project for a building owner to begin getting into HVAC.
    AOP Rules: Rules For Equipment Owners.

    Free online load calculator: http://www.loadcalc.net/


    There = not here. Their = possessive pronoun. They're = they are
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  3. #3
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    Is there a solenoid valve?

    How did you pressurize from the evaporator coil?

    What's a collector?
    Attached Images Attached Images

  4. #4
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    Quote Originally Posted by pecmsg View Post
    Is there a solenoid valve?

    How did you pressurize from the evaporator coil?

    What's a collector?
    This system does not have a solenoid valve.

    To pressurize the system, I connected my manifold gauge to the High side service valve at the Receiver Tank and the Low side service valve at the Compression. That was completed without a problem.

    When I couldn't get a good vacuum to hold at 500 microns or below is when I knew the system had moisture and attempted to blow out the system.
    I connected my manifold gauge with all valves closed to the high and low side service valves on the line set and attempted to blow out the system with Nitrogen paying attention to the max psi of the Evaporator which is 300 psi.
    I set the Nitrogen Regulator at just below 300 psi.
    With all the valves closed on the manifold I then slowly opened the inlet valve and then the low side valve letting in the Nitrogen flow and at 50 psi I closed the low side valve on the manifold. With no increase in reading on the high side gauge and slowly increased by 50 psi up to 150 psi and the low side gauge did not rise. I waited for 15 minutes and still no increase in pressure on the low side gauge.

    I apologize for using the wrong component name. It's not called a Collector, it a Receiver Tank.

  5. #5
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    Thread Starter
    Quote Originally Posted by kdean1 View Post
    Perhaps just break down and hire a contractor. This is not a good starting project for a building owner to begin getting into HVAC.
    Sorry for the grammar. I used most of the money I had and hired a professional and the system lost it's charge in 8 days. When I tried to contact them the phone was not connected any longer.
    I also am a license C7 contractor and understand how important it is to do the job correctly and understand how important it is to protect the trades.
    Thank You for your reply.

  6. #6
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    Quote Originally Posted by PBInstaller View Post
    Sorry for the grammar. I used most of the money I had and hired a professional and the system lost it's charge in 8 days. When I tried to contact them the phone was not connected any longer.
    I also am a license C7 contractor and understand how important it is to do the job correctly and understand how important it is to protect the trades.
    Thank You for your reply.
    So have you found and repaired the leak?

    Pulling a vacuum thru the manifold with those hoses hardly ever works.

    C7 licensed?

  7. #7
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    I pull a vacuum through my gauges, seems to work okay, I have an SMAN 360.

    If you have an EPA license we can help you, otherwise your not supposed to be doing this, regardless of other certs.

    Nothing personal against you, it would just be considered DIY type stuff which we can't help with.

  8. #8
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    Quote Originally Posted by Olivero View Post
    I pull a vacuum through my gauges, seems to work okay, I have an SMAN 360.

    If you have an EPA license we can help you, otherwise your not supposed to be doing this, regardless of other certs.

    Nothing personal against you, it would just be considered DIY type stuff which we can't help with.
    His profile states he is a building owner. That makes it DIY
    AOP Rules: Rules For Equipment Owners.

    Free online load calculator: http://www.loadcalc.net/


    There = not here. Their = possessive pronoun. They're = they are
    It's = contraction of it is. Its = the possessive form of it
    Too = also. To = expressing motion. Two = 2
    Then = after that, next. Than = indicates a comparison.
    Questions should end with a question mark "?" Statements end with a period "."

  9. #9
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    Well there you go.

  10. #10
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    No I haven't. But I pushed another 60 lbs of nitrogen through the system. 8 different times I purged with nitrogen and each time I got moister vapor coming out. Put the system on a pressure test for 40 hours.
    Going to try to vacuum it again tomorrow.
    And yes I have a C7 Low Voltage license.

  11. #11
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    Thread Starter
    Thanks for your wisdom. I will look into that EPA certification.

  12. #12
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    Quote Originally Posted by PBInstaller View Post
    Thanks for your wisdom. I will look into that EPA certification.
    Where are you located?

  13. #13
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    A C7 low voltage license?

    Don't know many licenses at all but does that qualify you for HVAC work?

    I mean, I'm all for helping people out but I do think there's merit in doing the EPA license as there's a lot than can go wrong when dealing with refrigerants specifically.

    So you purged it, 8 times, with a lot of nitro and you are getting moisture vapor? What is that? What does it look like?

    Are you trickling nitro through the system or blowing it through, because if you blow it through, you shouldn't be able to see a mist or at least I never have.

    Now, I've never had a TXV block me, and I do walk ins mainly, I've never had this problem, you know there's normally a liquid line solenoid valve right before the TXV at the evaporator or somewhere on the line. The walk ins I work on mainly are from like 2006 or so and they had LLSV on them, all of them, so I find it hard to believe, and with what you are telling us, that LLSV blocks pressure to the suction side, that's it's job so it REALLY sounds like you have one somewhere.

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