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  1. #1
    Join Date
    Oct 2007
    Posts
    20

    Liquid Line Noise

    Could you please comment on the following situation: (I have searched the forum but could not find a solution that pertains to my system setup).

    I have a Trane X19i with XV80 indoor unit, VS motor. The coil has TXV. When the system is in cooling mode - Stage 1, with a low load, ambient temp lower in the evening and mornings, the liquid line makes sloshing/gurgling noise righ at the coil.

    When the demand is higher - mid day, the noise is not present (still in Stage 1)

    There is no gurgling noise in Stage 2.

    I had a tech come out, he added a bit of R22 (while taking pressure readings in Stage 2 only). This helped a bit --- this was done in mid morning with ambient around 95F. However, the noise is still present when the load is low.

    I have a second system (two zones), X20i with XC80 and there is no noise on that system.

    Thank you in advance for your comments.

  2. #2
    Join Date
    Feb 2007
    Location
    S.E. Missouri
    Posts
    258
    I will be curious what is said as well. 4 year old 3 ton XL19i air conditioner with XV90 80k V3 furnace and 3 ton coil. Same exact symptoms you describe. Multiple service visits with no remediation. 2TTZ9036B1000BA TUY080R9V3W6 TXC036S3HPD0. Often wondered if it was low oil return on low stage. Wondered if 410 running higher pressure would make for better suction velocities.

  3. #3
    Join Date
    Oct 2007
    Posts
    20
    Thanks Silver06. Good to hear I am not alone :-). Indeed, it prof advice would be much appreciated on this. Should pressures be checked while the system is running in Stage 1. But then if it is charged in Stage 1, will Stage 2 be "overcharged"? Or is is the TXV that is modulating in Stage 1, when the load is low?

  4. #4
    Join Date
    Feb 2007
    Location
    S.E. Missouri
    Posts
    258
    I always wondered about what superheat the TXVs on these systems are supposed to run at the coil. The charging/performance chart with the outdoor system and the service manual with proper adjustments for furnace and coil combos and correct airflow and indoor wetbulb always have shown the proper readings on the graph, but this was always first done in second stage. It seems that when it goes from second then back to first, it doesn't gurgle in low stage until it runs for a long time in first or cycles off completely and starts again in first.

    The noise is definitely from the liquid line, right at the TXV. My evaporator coil is the copper/aluminum one, made right before the all aluminum coils. The TXV is an Emerson Alco ANCE 2 1/2 with non adjustable superheat.

    It seems that the evaporator is starved sometimes in first stage, even moving as little as 550 cfm. But once it is in second stage, the whole evaporator becomes active. I know for a fact the sensing bulb was kept clamped in place when it was brazed, always bugged me even though they used wet rags.

  5. #5
    Join Date
    Oct 2007
    Posts
    20
    "It seems that when it goes from second then back to first, it doesn't gurgle in low stage until it runs for a long time in first or cycles off completely and starts again in first.

    Ditto!

    The noise is definitely from the liquid line, right at the TXV.


    Definitely!

    It really be so helpful to hear from a professional what they think the issue might be. Any advice on how to approach the service folks would help, too. Perhaps, the problem is an inherent design fault and one just has to let go. The system does cool properly, it's just annoying as the blower is located in an inside closet.

  6. #6
    Join Date
    Jul 2004
    Location
    Charleston, SC
    Posts
    930
    Your service people are checking the refrigerant charge correctly, with the unit in 2nd stage. The noise that you are hearing is caused by refrigerant mass flow, which is lower in first stage. A mixture of liquid and vapor refrigerant is traveling through the line when only liquid should be present at that point.My suggestion for correcting this is to contact your service company and have them contact Trane tech support.

    Silver06, I am curious about the "It seems that the evaporator is starved sometimes in first stage" statement. What are the symptoms?
    "Customer Service" is not a department, it's an attitude!
    ???

  7. #7
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    2,487
    I think your problem is the refrigerant charge. The problem is the indoor coil volume is too small for the volume of the condenser coil. What happens is if it is charge correctly for cooling it is over charged for heating. There was a bulletin on this {don't remember that it addressed the noise but did the coil size} but the last year of the production of the 19i the only recommended coil was a 5 ton. The did have a charge robber that could be ordered to help with this problem. Again, I don't remember that it addressed the noise, but the noise is from refrigerant charge so it would stand to reason that it all plays together. I hear this on mine but only when it first starts. Once the blower reaches required speed the sound goes away. Have they checked air flow settings, mine is set for comfort R.

  8. #8
    Join Date
    Feb 2007
    Location
    S.E. Missouri
    Posts
    258
    Sorry I wasn't able to respond sooner. To cartercrew: the top 3 or 4 passes do not sweat, nor does the suction header, even after running in first stage for at least half an hour. The tube sheet only has rust below the top 3 tubing passes on either side of the coil. When unit was new, the two part suction manifold on the outside condenser would sweat enough on humid days that there would be a wet spot from the base pan on the control side. After that first cooling season, it never has sweat since. To kls-ccc: by charge robber, do you mean a receiver or accumulator? Also wanted to mention that the sump heaters on the compressors are working, verified with clamp amp meter by tech.

    This is an A/C only unit, not a heat pump. Airflow is set for 350 cfm per ton, 3 ton outside unit. TCONT402 thermostat with BK enabled with strategy 3 selected for blower ramp profile. 55% first stage airflow. Tech tried 400 cfm per ton with up to 70% first stage airflow. No change. Condenser and furnace/coil combo are on the same level. Lineset goes up exterior wall 8 feet, goes across a suspended ceiling in basement for 15 feet, down 3 feet to upflow evaporator. Brand new lineset with no joints except brazed ones at evap and condenser. Charge was added initially for extra lineset. I agree with jrhvac711, cools good but noise is annoying towards evening and morning in basement. Sounds like water from a faucet barely being opened with a knocking noise like a dull/muted water hammer effect.

  9. #9
    Join Date
    Oct 2007
    Posts
    20
    Thank you all so very much for your comments.

    Silver06: my lineset runs in a similar manner, drops down from ceiling to unit. Noise events happen exactly as you describe. All system components installed new.

    I'll try to run all this info by my contractor and/or Trane technical support. I am inclined to think it's a design fault in that for some reason in Stage 1, with a low load, as cartercrew says, "A mixture of liquid and vapor refrigerant is traveling through the line when only liquid should be present at that point"

  10. #10
    Join Date
    Feb 2007
    Location
    S.E. Missouri
    Posts
    258
    Totally agree about the mixture of liquid and gas. I guess this would cause lower capacity as the metering device would not have a solid column of liquid refrigerant behind it, causing flash gas I guess. Also, overcharging it to compensate would I guess result in less condensing surface area resulting in the condenser acting as a receiver equaling less efficiency. Like jrhvac711 said, I guess it might be a design flaw.

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