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Thread: How low do you pull vaccum?

  1. #41
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    Quote Originally Posted by skippedover View Post
    I'll stay out of the name calling, if that's okay. To bad if it isn't okay. Having said that, the trick is to evacuate to a reasonable vacuum as shown on a good micron gauge, which is attached to a good set of hoses and is being drawn down by a good quality, 2-stage, properly maintained vacuum pump. The trick is that once the minimum (deepest) vacuum is recorded, you need to turn off all the valves and then turn off the vacuum pump and wait. -> (I watched a guy shut the VAC off first, & contaminated VAC oil went zoom into the piping aah!...)

    It's always going to rise a little. So if you pull it down to "just" 500 microns, what does it hold when the valves are closed & pump is off? Not 500 microns. So if you want to know if the system is dry, you need to evacuate down to something below 300 microns, then turn the pump off and observe. If the vacuum rises above 500 microns, you're not done and need to continue to evacuate, as there's an indication of moisture still boiling away in the system. Now all of this may seem like it's unnecessary but that's what a lot of "technicians" say about charging systems too.

    But the DOE has done extensive research and guess what they've found? Only 30% of the systems in the USA are properly charged. The rest are either over charged or under charged. So there's "technician education" needed there as well.

    Likewise on the static pressures in ducts. The average static is over 1.0 inches of WC (total static). Yet installers don't think they need to do a load analysis. Bottom line, it's called being a wannabe or being a technician. Make your bed and lay in it.
    If airflow through the coil is too low you won't have a proper charged system or one that comes anywhere near its BTUH & EER Ratings. I tend to ignore SEER, it's a shot in the dark..

    You're charging to the heatload that the evaporator is absorbing, be it various ratios of latent heat or sensible heat.

    I would only use a TXV refrigerant metering device, first we should all check airflow so it's right, only then check the charge using subcooling & also checking to see if the TXV ias holding close to its rated superheat setting.

    Evacuation (triple evac purging w/ dry nitrogen 1st two times) becomes extremely important due to 410A refrigerant & especially type of oil used! - Darrell

  2. #42
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    Quote Originally Posted by jpsmith1cm View Post
    Don't waste yours or your boss's money.

    The Titan/Brute manifolds are CRAP! Try turning one of those neat little tapered plastic valve handles with wet, oily or greasy hands. They work great. NOT!!!

    The 4 valve, 4 hose manifolds are nice, but YJ really has a stinker on their hands there.
    Personally I never had a problem. I've had them for about 3-4 years. And they are due for replacement I guess since they are used daily. But they still work just fine.

    Uhm. I keep my hands clean, I keep the oil and grease on gloves.

    Wait, are you the "dirt ball" these commercial property owners tell me about?! I the story usually starts "The guy was nice enough but he didnt wear gloves or shoe covers..........."

    BTW, I buy all my own tools. I wouldnt "re buy" something that was junk. If my "hands are too dirty" to operate a tool I would find a new job.

  3. #43
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    some of you will disagree with me on this but today i started drying out a system using 2 merium u tube mercury absolute manometers. this will probably take 2/3 days before changing oil & breaking vac. with nitro. i really trust the manometers more than my micron gage, but before im done i will check with
    a micron gage to check its accuracy.

  4. #44
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    Quote Originally Posted by CynicX View Post
    Personally I never had a problem. I've had them for about 3-4 years. And they are due for replacement I guess since they are used daily. But they still work just fine.

    Uhm. I keep my hands clean, I keep the oil and grease on gloves.

    Wait, are you the "dirt ball" these commercial property owners tell me about?! I the story usually starts "The guy was nice enough but he didnt wear gloves or shoe covers..........."

    BTW, I buy all my own tools. I wouldnt "re buy" something that was junk. If my "hands are too dirty" to operate a tool I would find a new job.
    Hmm.

    If the customer took a little more pride in their equipment, I wouldn't have to lay in a puddle of grease to work on their GD case.

    If you've never worked on the oil system of a supermarket rack, then you will never understand what it is like to have a hose full of oil at 200# blow in your face. It's a blast.

    I'm not a "dirt ball" as you so kindly put it, but occasionally, I do get a little dirt or oil on my hands. I'm a mechanic, not a prima-donna.

    If a tool is designed to be used by mechanics, it should take the fact that sometimes, just sometimes, we might get dirty in the discharge of our duties. That manifold doesn't meet that standard.

    If you like them so well, I'll sell ya mine, less my DRSA, or course. CHEAP!!! I still have the original analogs that came with it.

    I buy my own tools, too. Sometimes, I make a mistake. This was one.



  5. #45
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    Quote Originally Posted by marvin View Post
    some of you will disagree with me on this but today i started drying out a system using 2 merium u tube mercury absolute manometers. this will probably take 2/3 days before changing oil & breaking vac. with nitro. i really trust the manometers more than my micron gage, but before im done i will check with
    a micron gage to check its accuracy.
    I have always wondered about something like that.

    I think that I would trust that more than I would trust some of the cheap digital gauges that I have seen.

    Google, here I come.



  6. #46
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    Quote Originally Posted by eastnctech View Post
    question do you guys use a vac tree im intrerested in one any info? trying to squezze a po # out of the boss different story. hoses have to leak just to get new ones
    I have a vac tree and it works good but think of just upgrading to better manifold with digicool gauges. I use always core removal tool and attach micron gauge there when I don't have a valve at the evaporator.

  7. #47
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    to tostaos.I don't need professional status on this site to say how it is in the real F-----g world.I have been doing HVAC for 30 years I don't have professional status on this site only because i have not tried to get it.It is not important to me.What matters is helping people and not busting their balls.Unless you know everything!!!!It means more to help people.I will stop helping people if that matters to you.!!! In a lab,fine pull vacuum for a week.When you have to get a system back on line,you do what is practical.If you have a dry systemlow on freon,why bwould you worry about pulling a deep vacuum!!!! Thais is the real practical world.If you suspect moisture ,fine pull down to 250 microns.Trust me,I have been there.And yes I owm a big 10 cfm vaccum pump and good micron gauge.Stop being an *******.Now go back outside and feed your cows.

  8. #48
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    Quote Originally Posted by tostaos View Post
    I have a vac tree and it works good but think of just upgrading to better manifold with digicool gauges. I use always core removal tool and attach micron gauge there when I don't have a valve at the evaporator.
    I would wait until the DC manifold is released.

    As I said before, now pleased with the larger YJ manifolds and am currently VERY impressed with the DRSA.

    I will buy the DC manifold when it hits the market and rid myself of the brute.



  9. #49
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    Quote Originally Posted by jpsmith1cm View Post
    I would wait until the DC manifold is released.

    As I said before, now pleased with the larger YJ manifolds and am currently VERY impressed with the DRSA.

    I will buy the DC manifold when it hits the market and rid myself of the brute.
    Yes, that's the manifold I am waiting for. A year ago DC was ready to release the stalker manifold but he must have abandoned that one for a reason and is working on a new one. Have you seen a picture of the new one somewhere?

  10. #50
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    Quote Originally Posted by tostaos View Post
    Yes, that's the manifold I am waiting for. A year ago DC was ready to release the stalker manifold but he must have abandoned that one for a reason and is working on a new one. Have you seen a picture of the new one somewhere?
    Have you seen any of the information or pictures of the new one, yet? It looks like a good product. Certainly up to Doug's high standards.



  11. #51
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    Quote Originally Posted by jpsmith1cm View Post
    I would wait until the DC manifold is released.

    As I said before, now pleased with the larger YJ manifolds and am currently VERY impressed with the DRSA.

    I will buy the DC manifold when it hits the market and rid myself of the brute.
    I'll have the Paradigm ASAP. I don't know if you were a member over at the other forum when I went manifoldless with my DC 1250. I was looking around for a couple of ball valves to make my own ball valve manifold. I had no luck with that, and to this day I have only a set of T's on the powerhead. The Paradigm is very close to the configuration I had in mind for the ideal manifold. I agree with you about the Titan, and that is exactly why I have no manifold at all on my DC's. the Titan is hanging naked in my garage in case of extreme emergency, such as when the backup set and all the backups to the backup set fail on the same day as the DC. IOW, they will never see gauges on them again.

    FWIW, and I'm not going to get into the debate....this time...., but knowing ahead of time where you were coming from, and understanding your postion fully on micron guages, I have to say that it looks as though you intentionally stirred up the pot. I found the thread to be entertaining, and even humorous, though it didn't necessarily have the same effect on some of the other guys involved in the debate. I can actually picture some of the guys who post to this forum using their turn signal at a crossroads in the middle of the desert with not a soul around for 50 miles. Some people are just like that. I can't condemn them for it, but I really don't want them insisting that I follow their lead either.

  12. #52
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    Quote Originally Posted by jpsmith1cm View Post
    Have you seen any of the information or pictures of the new one, yet? It looks like a good product. Certainly up to Doug's high standards.
    no, I haven't, do you have a link?

  13. #53
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    I have had a set of Digi cool gauges since they came out.I was one of the first in the southeast to buy a set.Also have a 5,a 6 and a 10 cfm vacuum pump.A digital J/B micron gauge and a vacunal tube(for those who know what that is) so don.t tell me i don,t know how to pull vacuum.I have dried out low temp 20 ton systems.But,If you want to use a micron gauge everday for normal evacuation,fine.It won't hurt.It is not necessary unless your system has been open a long time,exposed to moisture,or you suspect moisture.I am saying that i do what is practical and economical.

  14. #54
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    Quote Originally Posted by tostaos View Post
    no, I haven't, do you have a link?
    If you're looking for pictures of the new manfold, there are a couple in the "stalker" thread in the tool part of this forum. Look in the last few pages to find the pictures.

  15. #55
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    Quote Originally Posted by y7turbo View Post
    If you're looking for pictures of the new manfold, there are a couple in the "stalker" thread in the tool part of this forum. Look in the last few pages to find the pictures.
    thanks

  16. #56
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    Quote Originally Posted by tostaos View Post
    no, I haven't, do you have a link?
    Here's a sneak peek.
    Last edited by hvacrmedic; 02-04-2010 at 12:02 AM.

  17. #57
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    Quote Originally Posted by Gleng View Post
    I am saying that i do what is practical and economical.
    I have never known connecting up and using a micron guage to be impractical. Or to have a negative economical impact.

    Unless by negative impact, you mean it took longer to get a low vacuum then what was originally anticipated.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  18. #58
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    Quote Originally Posted by hvacrmedic View Post
    Here's a sneak peek.
    Thanks, I will wait for that, it should be out by spring.

  19. #59
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    O.K you have a valid point.If you want to always use a micron gauge that is fine.If the system is dry it will pull down quickly.I'm just saying that I usually don't use a micron gauge unless I suspect a problem,And i do have one on the truck.Never had a problem doing this in 30 years.

  20. #60
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    Quote Originally Posted by Gleng View Post
    O.K you have a valid point.If you want to always use a micron gauge that is fine.If the system is dry it will pull down quickly.I'm just saying that I usually don't use a micron gauge unless I suspect a problem,And i do have one on the truck.Never had a problem doing this in 30 years.
    There are very many levels of refrigerant system repairs. Some warrant pulling a deep vacuum and some don't. A typical filter dryer changeout for instance. Pump system down into the condenser. Cut out filter dryer, immediately install a new one. It's a dry day out, the liquid line tubing was open to atmosphere for less than 15 seconds. I'm certain that the new dryer will handle the femtogram of moisture that entered the tubing during this process, and in any case the nitrogen purge while welding will have swept that femtogram of moisture out before the vacuum pump is even attached. If the dryer won't be sufficient to this miniscule task, then why did I even put a dryer back in the system? Don't expect to be understood on this matter. No person of esteemed character is going to waiver from the "rule of law of 500 microns" for fear of having their ass jumped on, just like they have jumped on yours. Take it with a grain of salt, I found nothing inherently wrong with your reply.

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