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  • #16
    Re: R410a

    Originally posted by Flux View Post
    I should probably take blame for that, as I didn't spell that out from the beginning. I didn't think I had to say that, because I thought most people would know what I meant. I agree that time is only apart of what's important but micron reading is the deciding factor.

    What type of Micron gauge are you guys using that shows 500? Mine only goes to 30. Is there a special gauge for that?
    Flux, A micron gauge is designed for reading vac. Your gauges are not accurate enough... Your gauges read vac in inches of mercury (a very course measurement for our purposes). A deep vac is measured in microns.

    The lower the micron reading the better... A good vac is anything below 500 microns. I have found that I can see a leak in a system in a matter of minutes when pulling a vac using my digital micron gauge and my favorite pump...


    Here is the cheap-o that I use:

    http://www.yellowjacket.com/HVACRProducts.asp?t=HVACR&l=7&c=141&p=267

    Comment


    • #17
      Re: R410a

      Originally posted by Flux View Post
      I was taught one way as well, and had it reaffirmed (for the most part) in A/C school. There is more than one way to achieve any goal. I never have to go back on any of the units I install so..something is being done right.

      You've never had a DOA scroll?

      Comment


      • #18
        Re: R410a

        Originally posted by OkieBill View Post
        Flux, A micron gauge is designed for reading vac. Your gauges are not accurate enough... Your gauges read vac in inches of mercury (a very course measurement for our purposes). A deep vac is measured in microns.

        The lower the micron reading the better... A good vac is anything below 500 microns. I have found that I can see a leak in a system in a matter of minutes when pulling a vac using my digital micron gauge and my favorite pump...


        Here is the cheap-o that I use:

        http://www.yellowjacket.com/HVACRProducts.asp?t=HVACR&l=7&c=141&p=267
        While I was waiting for a response, I found it on Yellow Jackets website. I never knew this instrument existed. This is what happens when you're taught the old school way...I will have this instrument extremely soon.

        Comment


        • #19
          Re: R410a

          Originally posted by Flux View Post
          I should probably take blame for that, as I didn't spell that out from the beginning. I didn't think I had to say that, because I thought most people would know what I meant. I agree that time is only apart of what's important but micron reading is the deciding factor.
          IF when you valve off your pump and the reading holds. That's when you know for certain your system is dehydrated.
          If you ever worked with water cooled condensers you'll catch my drift.

          James

          Comment


          • #20
            Re: R410a

            Originally posted by James P View Post
            You've never had a DOA scroll?
            We probably put in less then 10 units per YEAR, as we are just a small family business, and most of our work is Plumbing & Heating.

            1 time we had a D.O.A scroll compressor. 1 other time we had a leak at the compressor, but the compressor was good. Twice that I remember, we had 2 different "A" coils that had pin hole leaks.

            I'm sure larger companies who put in 15-20 units a MONTH have a much higher failure rate.

            Comment


            • #21
              Re: R410a

              Originally posted by James P View Post
              IF when you valve off your pump and the reading holds. That's when you know for certain your system is dehydrated.
              If you ever worked with water cooled condensers you'll catch my drift.

              James
              James - A/C is definitely NOT my strong suit, and I'll be the first to admit it. I simply don't see it enough to get a better grasp of it like my father has. I only have my TYPE II certification, as I failed III by 2 questions. Like when I took that test..my brain hurt from the III part, cause I never seen/worked any of that stuff before.

              I'm thinking of going back this fall to take the R410a course they are just now offering in my area.

              Comment


              • #22
                Re: R410a

                Originally posted by OkieBill View Post
                Flux, A micron gauge is designed for reading vac. Your gauges are not accurate enough... Your gauges read vac in inches of mercury (a very course measurement for our purposes). A deep vac is measured in microns.

                The lower the micron reading the better... A good vac is anything below 500 microns. I have found that I can see a leak in a system in a matter of minutes when pulling a vac using my digital micron gauge and my favorite pump...


                Here is the cheap-o that I use:

                http://www.yellowjacket.com/HVACRProducts.asp?t=HVACR&l=7&c=141&p=267
                I forgot to check out your link..but I was looking at the digital one..didn't notice the cheaper version on their website until your link. Regardless..we will have one of these. Looking at the stuff they now offer..pops is behind the times!!! lol

                Comment


                • #23
                  Re: R410a

                  Originally posted by Flux View Post
                  I forgot to check out your link..but I was looking at the digital one..didn't notice the cheaper version on their website until your link. Regardless..we will have one of these. Looking at the stuff they now offer..pops is behind the times!!! lol
                  If you want to spend a little more for an old school model, here's one. I used this one for years without any problems.

                  James

                  http://www.trutechtools.com/Thermal-...571_p_631.html

                  Comment


                  • #24
                    Re: R410a

                    Pull the cores when pulling a vacuum and I wouldn't recommend going below 500 microns. You'll damage the reed valves in the compressor depending on it's style and pull oil from the compressor.

                    http://www.yellowjacket.com/HVACRPro...&t=HVACR&c=141

                    this is what I use for checking a vacuum. Pulling the core is the fastest way to do it as well as using the 3/8 vac hose. I also tap the compressor as you'll sometimes get moisture to be trapped under the oil. Also make sure the oil in the pump is good.

                    R410 is no different then r22. Just higher pressure you dealing with. As NHmaster said, wiegh the charge in and you'll be gold.
                    Buy cheap, buy twice.

                    Comment


                    • #25
                      Re: R410a

                      Also, if you're pulling a vac and leaving the pump unattended, better put a normally closed solenoid valve in line between the pump and gauges. otherwise, first time you lose power, you'll suck all the oil back at the pump.
                      Buy cheap, buy twice.

                      Comment


                      • #26
                        Re: R410a

                        Originally posted by gear junkie View Post
                        Also, if you're pulling a vac and leaving the pump unattended, better put a normally closed solenoid valve in line between the pump and gauges. otherwise, first time you lose power, you'll suck all the oil back at the pump.
                        I had an old Robinair pump that would suck the oil out of it, if it was unintentionally shut off.We used it on lithium bromide absorption chillers which it wasn't designed for. Probably why the check valve didn't work if it had one. The newer ones I thought had check valves built in. I've accidently shut off my JB pump while running and the oil stays put.
                        One of my old text books has the thing about the solenoid between the pump and system.
                        In your earlier post you state not going below 500 microns. How do you keep your pump from going lower? I've never heard of using a deep vacuum harming compressors.

                        James

                        Comment


                        • #27
                          Re: R410a

                          I close the valve on the pump, then the maniflod gauges once it gets close to 500 microns. I'll then let it sit for about 1/2 hour to see if there's any rise in microns. I do this to look for trapped noncondensables, not for checking for leaks. This can happen easily if your vacuum pump is to big.
                          Buy cheap, buy twice.

                          Comment


                          • #28
                            Re: R410a

                            Originally posted by gear junkie View Post
                            Pull the cores when pulling a vacuum and I wouldn't recommend going below 500 microns. You'll damage the reed valves in the compressor depending on it's style and pull oil from the compressor.

                            http://www.yellowjacket.com/HVACRPro...&t=HVACR&c=141

                            this is what I use for checking a vacuum. Pulling the core is the fastest way to do it as well as using the 3/8 vac hose. I also tap the compressor as you'll sometimes get moisture to be trapped under the oil. Also make sure the oil in the pump is good.

                            R410 is no different then r22. Just higher pressure you dealing with. As NHmaster said, wiegh the charge in and you'll be gold.

                            Gear, Let's talk

                            As long as you are pulling your vac through both sides their is no chance of reed valve damage in a scroll compressor if you pull a deep vac and I would be willing to bet that even if you pulled your vac from one side on a scroll it would not damage the valve as scrolls are not that tight.

                            If you manage to get your oil to flash to a vapor in a vac you have the wrong oil in your system The only thing that will pull your oil from the system or your pump is pressure blowing it out or gravity.

                            Tapping the compressor is a great tip for knocking entrained refrigerant out of suspension.

                            R410A is a very different beast from R-22 and should be treated as such...
                            -410A and 22 oil do not mix and will destroy a system quickly if they are mixed
                            -410A is an azeotrop (thus the A designation) each azeotropic blend has it's own quarks.
                            -NHmaster is correct in recommending to weight in the charge the only problem is that is not possible on a new installation (which is the posters issue) so you gotta know your PT chart / superheat / subcooling if you want to get it right.

                            Bill
                            Last edited by OkieBill; 08-20-2010, 08:18 PM.

                            Comment


                            • #29
                              Re: R410a

                              Some tech notes

                              http://www.teledyne-hi.com/app_notes...rigeration.htm

                              And on large power transformer oil purification which is a process similar ot evacing an AC system. You need to get any moisture out of the transformer oil. But most of you will not run into this unless you are replacing a transformer in a power plant.

                              http://www.teledyne-hi.com/app_notes...rification.htm
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                              Comment


                              • #30
                                Re: R410a

                                Originally posted by OkieBill View Post
                                Gear, Let's talk

                                As long as you are pulling your vac through both sides their is no chance of reed valve damage in a scroll compressor if you pull a deep vac and I would be willing to bet that even if you pulled your vac from one side on a scroll it would not damage the valve as scrolls are not that tight.

                                If you manage to get your oil to flash to a vapor in a vac you have the wrong oil in your system The only thing that will pull your oil from the system or your pump is pressure blowing it out or gravity.

                                Tapping the compressor is a great tip for knocking entrained refrigerant out of suspension.

                                R410A is a very different beast from R-22 and should be treated as such...
                                -410A and 22 oil do not mix and will destroy a system quickly if they are mixed
                                -410A is an azeotrop (thus the A designation) each azeotropic blend has it's own quarks.
                                -NHmaster is correct in recommending to weight in the charge the only problem is that is not possible on a new installation (which is the posters issue) so you gotta know your PT chart / superheat / subcooling if you want to get it right.

                                Bill
                                That's correct.

                                Comment

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