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  1. #27
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,467
    Quote Originally Posted by rmcfall View Post
    Old A/C was also 5 ton. The house is probably about 2400 square feet with a basement that is about 2000 square feet. The family room has vaulted ceilings that are about 15 feet tall. The basement is its own zone, which does not kick on in the summer.

    If setting the airflow limits to medium or low resolved the issue and the house still cooled just fine, would that create any problems with the unit itself? clipped...
    On a 5-Ton condenser with a TXV metering device feeding the cooling coil, I wouldn't want to get below 330-CFM per ton of cooling or 1650-CFM.

    You need a Tech that can & will measure the delivered airflow.

    When going for minimum airflow, when it comes to liquid-flood-back to the compressor, a piston flow rater orifice metering device is a bit tricky.

    Heat pumps have an accumulator which helps catch liquid flood-back.
    Old Frazer-Johnson A/C units used to have an accumulator in the condenser.

  2. #28
    Thanks for all the replies everyone. Let me ask these, the "Excess Static Pressure Stagedown" messages I am receiving are not FAULTS, but are events listed in the "Last 10 System Events" log within the Infinity service menu. I have never received any fault messages. Does that change anything?

  3. #29
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,774
    May not be an error. But. Its something to gt corrected. Before it gives you problems.
    Contractor locator map

    How-to-apply-for-Professional

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

  4. #30
    Join Date
    Jul 2011
    Location
    Argyle Tx 76226
    Posts
    66
    Quote Originally Posted by udarrell View Post
    On a 5-Ton condenser with a TXV metering device feeding the cooling coil, I wouldn't want to get below 330-CFM per ton of cooling or 1650-CFM.

    You need a Tech that can & will measure the delivered airflow.

    When going for minimum airflow, when it comes to liquid-flood-back to the compressor, a piston flow rater orifice metering device is a bit tricky.

    Heat pumps have an accumulator which helps catch liquid flood-back.
    Old Frazer-Johnson A/C units used to have an accumulator in the condenser.
    I have the 5 ton Carrier Infinity zoned system as well. Currently my CFM is 1487 and my Static Pressure is 1.11. What happens if it almost always runs below 330-CFM per ton of cooling or 1650-CFM.


    I am having some of the same problems as rmcfall, but I think that mine are somewhat worse. Some in this thread have already helped me with many of my questions, everyone else can take this as a personal invitation.
    Here is my complex problem:
    http://hvac-talk.com/vbb/showthread.php?t=910162&page=2

  5. #31
    Join Date
    Aug 2000
    Location
    Central Oregon
    Posts
    749
    From what I just gathered from all these threads is that your unit is doing exactly what it is suppose to do. ie Staging down due to excess static pressure. Your unit is sized for a whole house call with all dampers open. With only 1 zone calling it should be running at a reduced rate. Didn't your tech set your system up for you? If your A/C is not a 2stage this could cause issues for it.
    If you think our goverment is screwed up. You haven't lived in another country.

  6. #32
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,467
    Quote Originally Posted by bad install View Post
    I have the 5 ton Carrier Infinity zoned system as well. Currently my CFM is 1487 and my Static Pressure is 1.11. What happens if it almost always runs below 330-CFM per ton of cooling or 1650-CFM.

    I am having some of the same problems as rmcfall, but I think that mine are somewhat worse. Some in this thread have already helped me with many of my questions, everyone else can take this as a personal invitation.
    Here is my complex problem:
    http://hvac-talk.com/vbb/showthread.php?t=910162&page=2
    That is low airflow for numerous reasons some are running them that low; however, running that low, for many important reasons, they should have an accumulator & a TXV metering device.

    If it is a heat pump it will have an accumulator.
    Then you want to make sure it has a TXV metering device.

  7. #33
    Join Date
    Jul 2011
    Location
    Argyle Tx 76226
    Posts
    66
    Tempted, thank you. [From what I just gathered from all these threads is that your unit is doing exactly what it is suppose to do. ie Staging down due to excess static pressure. Your unit is sized for a whole house call with all dampers open. With only 1 zone calling it should be running at a reduced rate. Didn't your tech set your system up for you? If your A/C is not a 2stage this could cause issues for it.] [COLOR="Red"]Yes my ex-tech set up my system for me. My A/C is a 2stage. /COLOR]

    Kind of a long story of what we have been through with this system, much of which is posted in the referenced thread. We had the TXV (Not sure I have the 3 letters right while not looking at the receipt) valve replaced in July (Last year as well). I told the company that replaced the TXV that a friend of ours had an air conditioner replaced by the same company that installed ours. Our friend suggested that he have the original company come out and look at our system while we were out of town. One of the things that company said was something about our 2nd stage not working and needing to be replaced. We rode it out until July as we quit trusting them much earlier. When the company that replaced the TXV came out, we told them what we were told about the 2nd stage not working and needing to be replaced. He verified that it was not working and then said it was not receiving any power. We checked the breaker and it was tripped. It did not need to be replaced.

    udarrell, thank you for your reply. It appears to have a heat pump as going through the service menu, it gives readings for the heat pump. How can I make sure that it has a TXV metering device?

  8. #34
    Join Date
    Jul 2011
    Location
    Argyle Tx 76226
    Posts
    66
    I do have a heat pump. Does the heat pump also cool?
    How can I make sure that it has a TXV metering device?

    Fan coil/ Air handler Model# FE4ANB006000
    Heat Pump Model# 38YDB060321

  9. #35
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,467
    Quote Originally Posted by bad install View Post
    I do have a heat pump. Does the heat pump also cool? YES
    How can I make sure that it has a TXV metering device?
    Do U have the manual? Or, call the contractor.

    Fan coil/ Air handler Model# FE4ANB006000
    Heat Pump Model# 38YDB060321
    It will also have a suction line accumulator that will help protect the compressor against liquid slugging...

    Had the post ready to send & accidently closed the page!

  10. #36
    Join Date
    Jul 2011
    Location
    Argyle Tx 76226
    Posts
    66
    Our system has never worked correctly and the original contractor is not responding to our emails. He claims that our HVAC cools 20 degrees below the outside temperature and that is what it is designed to do. From talking to others in the thread that I started, that is not correct and the way he did the duct work is the main problem. I posted lots of photos of my duct work and some say it's borderline criminal.

    I think that this is the manual to my system:
    http://www.xpedio.carrier.com/idc/gr...t/fe4a-2pd.pdf

    Will it say in that manual if I have a TXV metering device?

  11. #37
    Join Date
    Jul 2011
    Location
    Argyle Tx 76226
    Posts
    66
    I see a thing that says it is Model BF-163S-XF connected to the outside unit. Is that a suction line accumulator or does it protect it in the same way?

  12. #38
    Join Date
    Apr 2011
    Location
    SE Washington
    Posts
    499
    Carrier has a design guide for Infinity zoning, cat # zone-01DG, quoted, when airflow limits are set to MAX, the maximum airflow allowed into a zone is 210% of the assessed airflow for that zone. example: If a zone size is determined to be 25% of the entire system, the leakage is 15% and the maximum airflow is 2250=> [(450)(5)] Airflow into this zone is 450 x5x1.5x (.25+.15)= 1350 cfm. Minumum airflow for a 2 ton system in high stage is 275 cfm/ton. The maximum airflow allowed into a zone set to MAX airflow is 1050cfm. The system will not turn on in high stage because this is below the minumum airflow required for high stage. The minumum airflow for low stage is 175 cfm/ton, the system will turn on in low stage and attempt to run full low stage airflow. a typical 2 stage bristol compressor system will run about 220 cfm/ton when set to efficiency low stage airflow which is 1100 cfm for a 5 ton. this is slightly higher then the maximum allowed into the zone, but well above the minumum for reliable operation. if the zone is very restrictive the system will attempt to dump air into other zones per the steps shown in the airflow limits and equipment protectionsection. if all steps are unsucessful, the system will shut down and register EXCESS STATIC PRESSURE event in last 10 system events.
    air flow summary
    the variable speed blower and the damper control algorithms work in conjunction to automatically maintain safe airflow levels thru the equipment under all conditions. Also, the airflow into any zone is limited to a maximum value. This value is set for each zone by the installer in the zone user interface install/service screens. The default factory setting is HIGH. the higher this setting, the more air can be delivered to each zone. unoccupied zones are used in a controlled manner to recieve excess air when needed. In a system where there are many zones of diffrent sizes and loads, ducts that are small or when there is evidence of zones not meeting setpoints, the installers remedy is to; create unoccupied zones within the system or increase zone airflow limits in problem zones

    dont know if that helps much but basically the smallest zone should be able to handle the full cfm output by itself, per design guide

  13. #39
    Join Date
    Apr 2011
    Location
    SE Washington
    Posts
    499
    You will not find a TXV on a carrier heat pump, they use a piston metering device in heat mode, the only exception beiing the new VNA Greenspeed which uses a EXV

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