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-   -   Poor Cooling - Goodman high efficiency (https://www.askmehelpdesk.com/showthread.php?t=11980)

  • Aug 21, 2005, 06:53 PM
    jkbutler
    Poor Cooling - Goodman high efficiency
    I have a two year old Goodman unit that does not cool properly. The suction line does not get cold - barely slightly cool. It is a 3-ton high efficiency unit with a 5-ton coil. The orifice size was changed from a 74 to a 73, which is now the recommended size. The pressures were 72 and 190 on a 90 degree day with barely any cooling and a loud gurgling sound coming from the lines. This noise was very obvious in the house. The lines are 3/8" and 3/4" and are approximately 50 feet long. I added refrigerant to bring the pressures up to about 80 and 200 at 90 degrees ambient outside and 74 inside. The noise has stopped but the suction line is still barely cool. It is not near as cold as it should be, and not near cool enough to sweat, so I am sure it is not dehumidifying the house. The installer is frustrated and thinks an evaporator coil change to a smaller coil is needed. He thinks the refrigerant is not flashing properly inside the coil to cool it. Goodman will not talk to me since I am a homeowner and not an installer. Would more refrigerant help? The unit outside is pulling about 10 amps with a nameplate rating of 13.5 for compressor and 1.6 for tha fan. The installer did not evacuate the unit before charging the last time, but he says it is not necessary. Any suggestions? I am very frustrated with a new high-efficiency unit that runs all the time and does not cool properly.
  • Aug 21, 2005, 07:19 PM
    labman
    I can't help with such a technical question, and have not seen any answers here from others suggesting they can. You may need to find a more technical forum.

    Perhaps Goodman would talk to the installer.
  • Aug 22, 2005, 04:47 AM
    hvac1000
    Help here
    Quote:
    Originally Posted by jkbutler
    I have a two year old Goodman unit that does not cool properly. The suction line does not get cold - barely slightly cool. It is a 3-ton high efficiency unit with a 5-ton coil. The orifice size was changed from a 74 to a 73, which is now the recommended size. The pressures were 72 and 190 on a 90 degree day with barely any cooling and a loud gurgling sound coming from the lines. This noise was very obvious in the house. The lines are 3/8" and 3/4" and are approximately 50 feet long. I added refrigerant to bring the pressures up to about 80 and 200 at 90 degrees ambient outside and 74 inside. The noise has stopped but the suction line is still barely cool. It is not near as cold as it should be, and not near cool enough to sweat, so I am sure it is not dehumidifying the house. The installer is frustrated and thinks an evaporator coil change to a smaller coil is needed. He thinks the refrigerant is not flashing properly inside the coil to cool it. Goodman will not talk to me since I am a homeowner and not an installer. Would more refrigerant help? The unit outside is pulling about 10 amps with a nameplate rating of 13.5 for compressor and 1.6 for tha fan. The installer did not evacuate the unit before charging the last time, but he says it is not necessary. Any suggestions? I am very frustrated with a new high-efficiency unit that runs all the time and does not cool properly.
    Best for you to have the contractor change the flow rater/piston to a expansion valve. You will also need a hard start device. Add a sight glass/moisture indicator to the liquid line. Charge unit until no bubbles are in the sight glass then check your super heat and other parameters of the condensing unit and the evaporator to make sure they are in spec. make sure that when the system is open for service you recover what ever refrigerant that will not pump down into the unit and you might consider installing a liquid line drier. This if done properly will square up your situation and give you all the cooling power your system is designed for. (I will also add that 50 feet of line creates a lot of friction loss. You really want the suction line to come back at a cool temperature to help with the colling of the compressor. Running the way it is can actually damage the unit. If you contractor does not know what I am talking about you better find a more qualified contractor).
  • Jul 30, 2007, 09:44 PM
    coolmrc
    First of all, the system should have been vacumned doown before staring it up. Second- you can't put a 5 ton coil on a 3 or 31/2 ton condenser. You need to match it exactly. Your 5 ton coil is saying that it can give you 5 tons of cooling only if you have an outside unit that can provide 5 tons of cooling, otherwise you get what is happening now. My god change you a/c man. If he doesn't know that, get rid of him... Good luck
  • Jul 30, 2007, 10:19 PM
    acetc
    Just noticed, this post is two years old!!
  • Jul 30, 2007, 11:19 PM
    jkbutler
    Quote:
    Originally Posted by hvac1000
    Best for you to have the contractor change the flow rater/piston to a expansion valve. You will also need a hard start device. Add a sight glass/moisture indicator to the liquid line. Charge unit until no bubbles are in the sight glass then check your super heat and other parameters of the condensing unit and the evaporator to make sure they are in spec. make sure that when the system is open for service you recover what ever refrigerant that will not pump down into the unit and you might consider installing a liquid line drier. This if done properly will square up your situation and give you all the cooling power your system is designed for. (I will also add that 50 feet of line creates a lot of friction loss. You really want the suction line to come back at a cool temperature to help with the colling of the compressor. Running the way it is can actually damage the unit. If you contractor does not know what I am talking about you better find a more qualified contractor).
    hvac1000, your reply was very good. His feeling was to replace the coil with one from a different brand that had an expansion valve. That pretty much took care of the problem. This installer has shown me the catalog where this coil is recommended for this unit . It is used with several different capacity condensing units, and you just use different size orifices to make it match the condensing unit. It does not work though. The expansion-valve coil did make a huge difference. I don't know if it is charged exactly right, but it is working much better, and I would say pretty good.
  • Jul 30, 2007, 11:25 PM
    jkbutler
    Quote:
    Originally Posted by coolmrc
    First of all, the system should of been vacumned doown before staring it up. Second- you can't put a 5 ton coil on a 3 or 31/2 ton condenser. You need to match it exactly. Your 5 ton coil is saying that it can give you 5 tons of cooling only if you have an outside unit that can provide 5 tons of cooling, otherwise you get what is happening now. My god change you a/c man. If he doesn't know that, get rid of him...... Good luck
    Apparently this is Goodman's way of consolidating production, because I have seen the catalog where this coil was specified for several different condensing units, and just used different orifices to match the condensing unit. He switched it to a different brand coil with an expansion valve, and it is much better now. Thanks for answering.
  • Jul 30, 2007, 11:35 PM
    hvac1000
    coolmrc

    We have used oversized coils for over 30 years. It makes for better moisture removal. It is not a problem but you have to use an expansion valve.
  • Dec 11, 2008, 08:01 PM
    Goodman cooling
    You had a install that did not know what he was doing! In the first place he should have confirmed a matching coil and piston and pulled a good vacum. And charged the system using super heat. If he had he would have know he was leaving your equipment not working properly. There isn't any thing wrong with goodman. Your charged gases should only be to the metering device from there the rest is flash gas. When your suction line is very cold . A suction line evaporator isn't doing its job. It's job is to remove the cold and replace it with heat. Any cold flooding back is a sign of inaffecancy. What he should have don if this was a new system was weigh in the gas he needed by reading the MFG specs. I LOVE DIY...

    Sales@goodmancooling
  • Jan 11, 2009, 08:42 PM
    Goodman cooling
    Quote:
    Originally Posted by hvac1000 View Post
    Best for you to have the contractor change the flow rater/piston to a expansion valve. You will also need a hard start device. Add a sight glass/moisture indicator to the liquid line. Charge unit until no bubbles are in the sight glass then check your super heat and other parameters of the condensing unit and the evaporator to make sure they are in spec. make sure that when the system is open for service you recover what ever refrigerant that will not pump down into the unit and you might consider installing a liquid line drier. This if done properly will square up your situation and give you all the cooling power your system is designed for. (I will also add that 50 feet of line creates a lot of friction loss. You really want the suction line to come back at a cool temperature to help with the colling of the compressor. Running the way it is can actually damage the unit. If you contractor does not know what I am talking about you better find a more qualified contractor).
    Sounds like the equipment Is Fine... sounds like it's the installer... The gentleman above answered it on the nail head... Sounds like you have been Hacked...
  • Jan 11, 2009, 08:44 PM
    Goodman cooling
    Quote:
    Originally Posted by Goodman cooling View Post
    Sounds like the equipment Is Fine.... sounds like it's the installer....The gentleman above answered it on the nail head.... Sounds like you have been Hacked....


    hvac1000 Your right on the money...
  • May 27, 2009, 01:41 AM
    Pro Air

    After reading all of the responses I will give my recommendation. First, Goodman as well as many other manufacturers have a common practice of providing an oversized evaporator coil match to their condensing units. You must use the designated piston/flowrator/accutron etc. sized to match the condensing unit. Based upon my experience of 20 years +, the most precise way of charging is to weigh in the charge for the line set length, coil size. HOWEVER this is not very practical. What is practical is to use a wet bulb (non-TXV) chart to give precise superheat based upon latent and sensible load on the evaporator coil, and outside ambient condition. It sounds like you got pretty close when you converted to a TXV (thermostatic expansion valve), however to properly charge a TXV system, "most" manufacturers want you to charge by system sub-cooling. (Goodman does, typically 9-12 degrees at the liquid line). Also your 3/4 suction line @ 50 ft run is undersized and will effect system performance some. With the TXV installation, you need a hard start kit, even with a scroll compressor, Goodman/Copeland compressors has released a service bulletin stating this.

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