Page 1 of 3 123 LastLast
Results 1 to 13 of 35
  1. #1

    Confused moisture, or just impatient?

    hey all. i just registered and joined. i hope this is the right area to post. if not, i apologize, and expect a message to arrive in the inbox...

    reason for it was becasue i'm getting more and more into the hvac repair. specifically commercial residential for r22 and 410a. i work for an apartment complex, both properties together are well over the 2200 unit range, and every one has a split system, and natural gas furance for heat....yeah, 2200x2 problems. dont forget sinks and toilets....

    anyways, back to topic. for some reason i've been chosen is because it seems out of the 6 that have cert to handle freon, i'm the one that can braze. with that, comes the fact i've been running into some wild, crazy and cooky installs. today the best was 410a with solder joints and no filters....

    anyways. i've been having my hit and miss pulling vacuum. some times it's 15 mins to strike 300, others, it's been well over 4 hours. in my past time i do ALOT of AC/DC stick welding, MIG/TIG, and gas. so i have a good idea what a crap bond looks like. and i don't do garbage booger globby Rocky mountain range brazing, i puddle the stuff smooth and neat. yet the bond looks nice, it takes forever to pull a vacuum.

    new robinair, i change oil every time, and i buy it in the quart just so the jug doesn't attract moisture before the next job. digital micron guage.
    with limited tools, as the company provides what i 'need', which involves pulling teeth to get what i want, is a in service core remover, digital gauge, charge/test manifold, and the other oods and ends, scale, torch kit, etc.

    once everything is glued together. i remove the service cores, and dousche nitrogen through it. and i'll admit, i get wild and go through it like it's compressed air. company paid for it. why not? while it's spewing out. i'll spin a core in. wait for it to build up pressure. quickly remove the host and as fast as possible spin in the other core so i have postive sterile nitrogen in the linset.

    i understand purging the lines, which i found out recently is news to my fellow coworkers... "you purge the lines?" "huh? what's that?".....
    i use the core remover on the low side to remove the core from the unit itself, and also the service port on the core remover tool itself. this gives me unrestricted vacum acess. high side i attach the micron gauge, which the adapter for it has a service port as well. so i hook up the high side on that, just so i can get an idea what's going on once i get things rolling.

    all this takes place with positive nitrogen pressure in the system, just so i know all atmospheric contamints have been removed. so i hose up the pump and start pulling vacuum, teasing it at first, as i don't want to blow the oil out of the pump. eventually it'll pull vacuum. but using this method, as i said, it's hit and miss. sometimes it's hours, sometimes it isn't. should i be using a flush kit? am i pulling moisture out of old oil that's been serviced by sloppy methods? i guess that's my biggest question. i dont' think i' doing things 'wrong'. i'm trying my best to keep the vacuum sterile, and to do this, i keep the manifold gauges hooked up, so all i need to do is move the hose from the vacuum to the supply tank, purge the line, and away i go.


    i guess i'm asking if i'm doing things right and fighting a nightmare, or if i'm doing things wrong with the tools i'm provided....


    jason

  2. #2
    Join Date
    Feb 2012
    Location
    EVERYWHERE
    Posts
    229
    Sounds like you are doing a good job. 410A will take longer then R22 because of the poe oil also you should always have a new drier on a 410A unit whenever you open the system. Also it might speed up the vacuum if it seems to be taking a long time to stop pump add nitrogen to system up to like 10psi and then restart vacuum.

  3. #3
    Join Date
    Feb 2006
    Location
    Phoenix,AZ
    Posts
    2,895
    Why would you vacuum the nitrogen out. Just let it blow!!!!

  4. #4
    Join Date
    Feb 2012
    Location
    EVERYWHERE
    Posts
    229
    Quote Originally Posted by KB Cool View Post
    Why would you vacuum the nitrogen out. Just let it blow!!!!
    So you can be 100% sure nothing get in once the nitrogen is gone. I will say you can let it get down to lower then 20psi tho down to like 5psi.

  5. #5
    Quote Originally Posted by KB Cool View Post
    Why would you vacuum the nitrogen out. Just let it blow!!!!



    Quote Originally Posted by FixItRight View Post
    So you can be 100% sure nothing get in once the nitrogen is gone. I will say you can let it get down to lower then 20psi tho down to like 5psi.
    Paid by the hour, not the job. regardless I see your point :-) I gave it thought, I still open valves only 1/4 way... :-D

  6. #6
    Quote Originally Posted by FixItRight View Post
    Sounds like you are doing a good job. 410A will take longer then R22 because of the poe oil also you should always have a new drier on a 410A unit whenever you open the system. Also it might speed up the vacuum if it seems to be taking a long time to stop pump add nitrogen to system up to like 10psi and then restart vacuum.
    I've tried that. Vacuum to 2000 then tease a few pounds of nitrogen to help carry moisture out towards the pump, sometimes it helps, sometimes still takes a while.

  7. #7
    Join Date
    Feb 2012
    Location
    EVERYWHERE
    Posts
    229
    Quote Originally Posted by chill4good View Post
    I've tried that. Vacuum to 2000 then tease a few pounds of nitrogen to help carry moisture out towards the pump, sometimes it helps, sometimes still takes a while.
    I would say if it still get to 500 micron and holds you don't have a issue.

  8. #8
    Its a cheap step gauge, flashes at micron levels...

    15", 5000,2000,1000,500,250,100,50,25

    Flashing 500 could be 430 or 260....... rarly illl make 250. Not sure if it's nasty oil or my method

  9. #9
    Join Date
    Feb 2006
    Location
    Phoenix,AZ
    Posts
    2,895
    I don't know!! seems like letting it blow with the valve cores out would carry the moisture best. I wouldn't dare try to vacuum a big puddle of water from a pipe. I would blow it out instead!!!!

  10. #10
    Join Date
    Feb 2012
    Location
    EVERYWHERE
    Posts
    229
    Your method is good. 250 is overkill anyway 500 is what you want to see. You can try and change to vacuum pump oil next time it takes long unless you mean nasty oil as in unit compressor oil and then you can try to change it. On 410A if it have a leak and lost the whole charge it is a good idea to change oil in unit.

  11. #11
    Join Date
    Feb 2012
    Location
    EVERYWHERE
    Posts
    229
    Quote Originally Posted by KB Cool View Post
    I don't know!! seems like letting it blow with the valve cores out would carry the moisture best. I wouldn't dare try to vacuum a big puddle of water from a pipe. I would blow it out instead!!!!
    You don't want to vacuum out a puddle of water is right, but why would you have that much water in your system in the first place. Seems like he is working on splits under 5 ton for the most part and that should not have that much water in them from just being open for a repair or having a leak.

  12. #12
    Join Date
    Aug 2010
    Posts
    3,525
    How old is the oil in vacuum? some here say that oil should be changed after each encounter with a wet system.

    In any case, you can't dry wet POE like you can mineral.

  13. #13
    Good. Alright. Now if I can teach coworkers to not contaminate my progress!!

Page 1 of 3 123 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event