Announcement

Collapse
No announcement yet.

Replacing refrigerant in my ac.

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Replacing refrigerant in my ac.

    Went from r-22 to NV-22 B in my central air.
    System seems to be much less efficient.

    Normal?

    Story to follow.

  • #2
    The pressure requirements on the newer refrigerants are much higher than older Freon.

    Comment


    • #3
      Originally posted by fixitright View Post
      Went from r-22 to NV-22 B in my central air.
      System seems to be much less efficient.

      Normal?

      Story to follow.
      Possibly. I don't think there is any R-22 replacement that performs exactly the same as R-22 - they will be less efficient as the replacement refrigerants don't have the same physical properties as R-22.

      Having said that it could also be installer error. Was the replacement charged correctly? You typically don't charge by the original weight but by superheat/subcooling depending on the system. In other words the actual refrigerant line temps are the things to monitor rather than the pressures.

      Did you do this yourself?

      Comment


      • #4
        Can you change refrigerants types and expect more or less the same performance or does a system have to be designed to do either types?

        If the latest refrigerants are less efficient does this mean changes in design to the coils, line set, condenser as well as higher pressures?

        I'm looking at getting a heating and AC unit in a couple of years and I'm sort of curious.

        Comment


        • #5
          Originally posted by Mightyservant View Post
          Can you change refrigerants types and expect more or less the same performance or does a system have to be designed to do either types?

          If the latest refrigerants are less efficient does this mean changes in design to the coils, line set, condenser as well as higher pressures?

          I'm looking at getting a heating and AC unit in a couple of years and I'm sort of curious.
          It's a complex subject. Refrigerants have widely varying characteristics. In addition as you know many older refrigerants are now banned due to harming the ozone layer and lately have a greenhouse effect. A lot of the replacement refrigerants are blends which have other issues such as temperature glide and fractionation.

          R-22 is now no longer in production - there are many drop in replacements such as the one mentioned at the start of the post - but they don't perform as well as the original refrigerant for which the equipment was designed for.

          If you are getting something new it should not be an issue since it would be designed for the newer refrigerant.

          Most systems there days are designed for R-410A which operates internally at much higher pressures than R-22 so the components such as compressors are different. They are not interchangeable.

          R-410A is expected to be phased out in the future as well. It looks like R-32 will be the replacement.

          R-410A should be available for a long time though if you are planning get a new unit and it happens to be R-410A. I have a 30 lb cylinder of R-22 but I believe it is quite expensive now.

          Comment


          • Mightyservant
            Mightyservant commented
            Editing a comment
            Thank you : )

          • Plumber Punky
            Plumber Punky commented
            Editing a comment
            r22 is in production until 2020. cost of 22 varies widely across the US. Where I am best cost is about 565 a jug. Out west it's down around 430.

        • #6
          Of the 2 replacement refrigerants you mentioned which of the two types would be preferred?

          Are either of these 2 replacement refrigerant being used internationally?

          Since the newer refrigerants don't perform as well as R22, how will this affect existing system in terms of equivalency? Are there simple changes that can be made to offset the loss of performance?

          Comment


          • #7
            Originally posted by Mightyservant View Post
            Of the 2 replacement refrigerants you mentioned which of the two types would be preferred?

            Are either of these 2 replacement refrigerant being used internationally?

            Since the newer refrigerants don't perform as well as R22, how will this affect existing system in terms of equivalency? Are there simple changes that can be made to offset the loss of performance?
            R-410A was the replacement for R-22 internationally. I believe most new a/c systems are sold internationally are for R-410A. Regarding R-32 - this is showing up I think a lot more overseas than in the US especially with ductless mini-splits which are popular in some parts of the world. I suspect it or probably another refrigerant will replace R-410A in the US - something with a lower GWP.

            As far as R-22 - the loss of efficiency I believe is due to drop in replacements for R-22 - I don't believe they work as well as R-22 in equipment designed for R-22. For equipment designed for a specific refrigerant that should not be an issue since the design should take care of it. In the case of the original post - NU-22B which is actually R422B (as per the official ASHRAE classification) - it is supposed to be a drop in replacement for R-22 but in reality I don't think any of the drop-ins work as well as the original. R422B is likely a blended refrigerant as well since it is in the 400 series of refrigerants - not a single compound like R-22. It may have a significant glide - not need to check the P-T relationship for that.

            Comment


            • blue_can
              blue_can commented
              Editing a comment
              It could well be that the unit is sized correctly. But 20 years ago it was typically sized by rules of thumb. I think the original ASHRAE research (on which the ACCA standards are based) was done about 22 years ago. These days sizing a/c systems involve analyzing a home based on its orientation, design, shading factors etc. You typically do a block load calc for the overall sizing and then a room by room load calc for duct sizing and design. If you did not go through that process even the ducts you recently installed are not based on some form of load calc so it may well be ok but then again it may not.

            • Mightyservant
              Mightyservant commented
              Editing a comment
              I would have to agree with you that it was rule of thumb. Even in our trade much was done "rule of thumb" and the rules were stretched to say the least. Much has changed I think largely in part to technology that can quickly run calculations and help optimize MEP systems.

              Thank you for the educating responses : )

            • Plumber Punky
              Plumber Punky commented
              Editing a comment
              407C works far better than 422b. It's very very close to 22 performance and doesnt require expensive oil changes or major retrofits.

          • #8
            Thanks for the responses. Now for the Story.

            My townhouse is for sale and of course it's a might warm now for Minnesota and my AC goes out completely.
            Thing runs but no cold. I have a temp difference of 15 degrees from before and after the A Coil.

            Go on the local Facebook page for a company to fix it as folks are looking at my place.
            He gets here and tells me the outside unit is dirty and needs cleaning.
            Sounds fair and so it gets clean but a screw gets into the radiator part and no more Freon.

            He silver solders the unit, pressure tests the unit and puts in NV-22 B and it still doesn't cool the house.

            He sucks out the NV-22 B, replaces the expansion valve and re-inserts the NV-22 B.

            We have a good temp difference again at about 15 degrees.

            Inside house temp was 86 degrees at 3:00, by midnight it was 85 and the next day it was 75 with the
            thermostat set at 72. I have a well insulated home with an outside temp of 88 to start and 70 in the morning.
            The unit ran the whole time. $$$

            It's keeping up now but running full time. The tech came back and was befuddled.
            He seemed to be the parts replacer type until something worked.

            End of story but this thing never ran this hard to keep up.

            Answers?

            If I have the outside unit replaced will I need to replace the A coil system?


            ( have gotten some healthy nibbles on the place but hate to sell it with a bad AC unit)

            Comment


            • #9
              Originally posted by fixitright View Post
              Thanks for the responses. Now for the Story.

              My townhouse is for sale and of course it's a might warm now for Minnesota and my AC goes out completely.
              Thing runs but no cold. I have a temp difference of 15 degrees from before and after the A Coil.

              Go on the local Facebook page for a company to fix it as folks are looking at my place.
              He gets here and tells me the outside unit is dirty and needs cleaning.
              Sounds fair and so it gets clean but a screw gets into the radiator part and no more Freon.

              He silver solders the unit, pressure tests the unit and puts in NV-22 B and it still doesn't cool the house.

              He sucks out the NV-22 B, replaces the expansion valve and re-inserts the NV-22 B.

              We have a good temp difference again at about 15 degrees.

              Inside house temp was 86 degrees at 3:00, by midnight it was 85 and the next day it was 75 with the
              thermostat set at 72. I have a well insulated home with an outside temp of 88 to start and 70 in the morning.
              The unit ran the whole time. $$$

              It's keeping up now but running full time. The tech came back and was befuddled.
              He seemed to be the parts replacer type until something worked.

              End of story but this thing never ran this hard to keep up.

              Answers?

              If I have the outside unit replaced will I need to replace the A coil system?


              ( have gotten some healthy nibbles on the place but hate to sell it with a bad AC unit)
              OK so he punctured your condenser coil with a screw and let out the refrigerant that was in there during cleaning?

              You say the delta T was 15 degrees before the guy got there but it was not cooling and he said the condenser was dirty? I suppose that is possible since a dirty condenser would not be rejecting heat and so that could cause the evaporator temp to rise.

              How did he know to replace the expansion device? Guesswork or based on pressure/temperature readings. Sounds like he may have put some debris into the system while silver soldering and plugged up the expansion device.

              It is possible his repair has left something in the system causing it not to cool properly. Either that or it was not charged correctly. As I mentioned one would need to see all the pressure temperature readings to see what is going on.

              Hard to believe a drop in replacement would perform so badly but I don't have direct experience with using this refrigerant.

              As far as replacement - if you get a system it will likely be R-410A so the indoor coil will need to be changed and matched to the outdoor unit.
              Last edited by blue_can; 07-11-2018, 11:04 PM.

              Comment


              • #10
                I'd like to mention 421a as a drop in replacement for R22. Direct drop in replacement which requires only changing Schrader valves and the filter drier. Pressures and temps are the closest to R22 of any drop in available. Slightly MORE efficient than R22. After a lot of research we decided to try it a few years ago in a system we had to open (TXV replacement). Went very well, used a few ounces less with slightly better splits. We've done 9 more systems since (any time we need to open a system for repair) and they all operate flawlessly. It's a blend and is fairly cheap as well. Just my opinion.

                Comment


                • #11
                  Originally posted by fixitright View Post
                  Went from r-22 to NV-22 B in my central air.
                  System seems to be much less efficient.

                  Normal?

                  Story to follow.
                  Yes, normal. There's capacity loss with alternate refrigerants. 407C appears to be the current front runner in regards to cost, efficiency, and retrofitting.
                  ~~

                  ... it was plumbed by Ray Charles and his helper Stevie Wonder

                  Comment

                  Working...
                  X