Page 1 of 3 123 LastLast
Results 1 to 13 of 31
  1. #1
    Join Date
    May 2011
    Posts
    8

    "Rotted coil" Explain please!

    I have two systems in our home, one for upstairs and one for down. Both are identical, but we only upgraded the downstairs when we bought the home 5 years ago because we rarely use the upstairs.

    It's a Trane system approx 20 years old. XL1200 outside....been reliable except for the Cap needing replacement.

    Downstairs runs amazing since we replaced the inside coil with a TXH033A4HPA2 high efficiency coil and a new trane furnace with variable speed fan, and never having replaced the XL1200's outside (3 ton downstairs and 2 ton upstairs)

    Upstairs is still all the original system.

    Now I am using the upstairs more often and when we turn it on, we get a "musty acrid" odor. The unit leaks a lot of water from the unit into the drip pan and then outside. It is rusty in color, so I am sure hte odor is from the rusting. THe drain to the outside has a constent drip drip when the unit is running. It cools....probably not at its peak and certainly not as good as the downstairs, but it works.

    My AC people tell me that the "coil is rotten" and needs replacement.

    I'm a little perplexed at exactly what "rotted out" means?

    1) I am sure the coil is constructed with copper/aluminus so what would be "rotted"

    2) Where is the rust coming from, and the rusty odor?

    3) Why is so much water being produced?

    I was given a price of over $ to replace the coils. I REALLY cant afford that sort of repair right now, so I am trying to figure out, if there is anything that can be done, such as opening up the unit and cleaning the coils or something to stop the water dripping. I am assuming that the rust smell might be comming from the inside of the airbox from all the water being pooled inside and slowly over many years rusting the metal.

    The unit runs well otherwise, so I dont want to have to spend $ bucks right now unless absolutely necessary.

    Thanks
    Last edited by beenthere; 05-05-2011 at 04:34 PM. Reason: prices

  2. #2
    Join Date
    Sep 2006
    Location
    Montana
    Posts
    983
    What they are probably referring to as "rotted" out is the drain pan for the evap. coil If it's a fairly old system, it probably has a metal drain pan that has rusted out over the years and is now leaking. I would recommend not running the system until you fix the problem, or you're going to be spending more money than just replacing coil. I would say you have a few options, depending on your budget and the age of the system. You could see if there is a replacement drain pan available, and just replace that. You could replace the evap coil and continue to use the condensing unit The third option would be to replace the system. Depending on the age, you have to look at what the best investment is going to be based on the cost of the different repairs. You'd hate to spend a bunch of money on a 15-20 year old system by replacing the coil or just the pan to have the compressor fail later in the year. Now the money you spent to "get you by" is completely lost. Just some things to think about.

  3. #3
    Join Date
    May 2011
    Posts
    8

    the water

    Can you explain where all the water is coming from? I dont see this much water if any in the new system, so how is this water being produced?

    As for the drainpan, are you referring to the one that sits below the coil on the outside of the unit, or is there another drain pan on the inside?

    Also, why do you recommend "not to run the system until it is fixed" before it causes more problems? If you are worried about water damage to the area....not to worry, that is all taken care of and no water would create damage if the pan rusted completely through.

    Thanks

  4. #4
    Join Date
    Jan 2010
    Location
    Athens GA
    Posts
    1,234
    Quote Originally Posted by david99 View Post
    Can you explain where all the water is coming from? I dont see this much water if any in the new system, so how is this water being produced?

    As for the drainpan, are you referring to the one that sits below the coil on the outside of the unit, or is there another drain pan on the inside?

    Also, why do you recommend "not to run the system until it is fixed" before it causes more problems? If you are worried about water damage to the area....not to worry, that is all taken care of and no water would create damage if the pan rusted completely through.

    Thanks
    The water you are talking about is the humidity that is in the air in your house.This draining is desireed as its the humidity that you feel most when its hot.The air that stays in your duct system continues back into the house with less humidity than before.
    The pan that is being talked about is the one inside the coil box.It is located at the bottom of the coil .It has a large area in the middle to allow air to push through the coil so it can give up its heat and humidity.Its job isd to catch this condensate (humidity) and drain it through a pipe (usually plastic PVC)to get rid of it.
    The reason we say not to run the unit is because the way your unit is now ,its leaking on everything under the coil box,usually an electrical motor and a metal blower wheel.
    There is no0 way to stop rust as it is like old age.Some of the newer coils have plastic pans that do not rust.
    Good luck.

  5. #5
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,422
    The "pan" under this unit is what we call a "back-up pan" and only should catch water when the interior drain pan is either rusted out (as yours is from the rust appearance), or the exterior drain pipe is plugged. This back-up pan usually is not made to be used as the day to day primary drain pan, and sooner (or later) it will fail and the water will come thru the ceiling (and make a horrible mess).

  6. #6
    Join Date
    Aug 2004
    Location
    Kentucky, Michigan, Ohio, Arizona, Colorado, Nevada, and Califormia
    Posts
    318
    The others are exactly right the coil pain is rusted out. A very common issue though is a system of that age probably will not have replacement pans available and if they are available the screws that hold the pan to the coil, most of the time the heads rust off at about the same time frame. You would do well to listen to those advising against good money after bad. Although I don't think you're in any danger regarding electrical issues because chances are the unit is horizonal left or right, there is a great potential for property damage due to the water. Also having the interior of the air handler saturated for so long can produce mold problems.
    "Surprised ?! If I woke up tomorrow with my head sewn to the carpet, I wouldn't be more surprised."
    Clark Griswold

  7. #7
    Join Date
    May 2011
    Posts
    8

    Thank you

    Thanks everyone, now I understand what is happening and I appreciate all the help.

  8. #8
    Join Date
    May 2011
    Location
    Houston, Texas
    Posts
    27
    Your coil is leaking and low on refrigerant so if you continue to run it you will burn out your compressor in your outdoor unit as well. If this unit is 20 years old you would be lucky to get away with just replacing the coil. The reason it is rusting is because contaminants get into the system and create acids which in turn corrode from the inside out. This could be the cause of the rust. A leaking coil is often times the first culprit of the domino effect.
    Your indoor coil is leaking refrigerant and is the reason you have excessive condensate.As refrigerant flows it takes oil with it which is responsible for keeping your compressor running slick, without it your compressor will dry up and burn out. It will also begin to leak refrigerant.
    Replacing the coil is the cheapest short term fix but you should still consider a new complete system. They will save you money; on repairs and electricity, and will turn out cheaper in the long run. Not to mention you will be more comfortable and less stressed.

  9. #9
    Join Date
    Jan 2002
    Location
    Ft.Worth,Tx
    Posts
    4,584
    Quote Originally Posted by david99 View Post
    I have two systems in our home, one for upstairs and one for down. Both are identical, but we only upgraded the downstairs when we bought the home 5 years ago because we rarely use the upstairs.

    It's a Trane system approx 20 years old. XL1200 outside....been reliable except for the Cap needing replacement.

    Downstairs runs amazing since we replaced the inside coil with a TXH033A4HPA2 high efficiency coil and a new trane furnace with variable speed fan, and never having replaced the XL1200's outside (3 ton downstairs and 2 ton upstairs)

    Upstairs is still all the original system.

    Now I am using the upstairs more often and when we turn it on, we get a "musty acrid" odor. The unit leaks a lot of water from the unit into the drip pan and then outside. It is rusty in color, so I am sure hte odor is from the rusting. THe drain to the outside has a constent drip drip when the unit is running. It cools....probably not at its peak and certainly not as good as the downstairs, but it works.

    My AC people tell me that the "coil is rotten" and needs replacement.

    I'm a little perplexed at exactly what "rotted out" means?

    1) I am sure the coil is constructed with copper/aluminus so what would be "rotted"

    2) Where is the rust coming from, and the rusty odor?

    3) Why is so much water being produced?

    I was given a price of over $ to replace the coils. I REALLY cant afford that sort of repair right now, so I am trying to figure out, if there is anything that can be done, such as opening up the unit and cleaning the coils or something to stop the water dripping. I am assuming that the rust smell might be comming from the inside of the airbox from all the water being pooled inside and slowly over many years rusting the metal.

    The unit runs well otherwise, so I dont want to have to spend $ bucks right now unless absolutely necessary.

    Thanks
    Moisture inside seal cabinet with aluminum /galvanized sheet metal pan causes rust, as rust builds it tends to climb the coil outer area, then with dirt and debris coil gets colder and increase the amount until you get (rotten coil) then you need to replace it... Cost more to operate this type of old coil too..
    "Everyday above ground, is a good day".
    "But everyday that you have made a difference in someones life, may insure you stay above ground a little longer".<aircooled>

  10. #10
    Join Date
    Jan 2011
    Location
    Massachusetts
    Posts
    81
    I agree,when a coil pan leaks it makes the chances of ceiling damage alot higher think of the coil sitting in a metal tub the metal tub corrodes like a metal pail will the moisture being removed from the air runs into that pan and to the drain line

  11. #11
    Join Date
    Nov 2008
    Location
    Chapel Hill, NC
    Posts
    1,070
    By "rotted coil" they may mean a rusted/corroded coil which would need to be replaced or a mold-covered coil which you should be able to clean off. Either could produce the musty smell but the latter is the most likely culprit. It also sounds like you have a leak from the condensate drain area. That needs to be fixed also. Depending on what needs to be done (which isn't always what the say needs to be done) you might be better off getting a new furnace/air handler.

  12. #12
    Join Date
    Oct 2006
    Location
    The Beach
    Posts
    680
    Call a second pro and let him check out your entire system. Tell him you have little money right now and give you a price on just fixing what is wrong at this time. A lot of my calls are the same. I am ask to just make it run a little longer if I can. We all know what can be done to help our coustomers. Times are still rough and they do not have any extra money. Some of my long time coustomers never get a bill. They cannot pay so why send them a bill.

    Happy Mothers Day to all those wonderful ladys that changed our dippers for 18 years or longer.
    Blue Fox

  13. #13
    Join Date
    May 2011
    Posts
    8

    New info on problem

    Based on all your info and with my small amount of knowledge in the area (I come from a construction family) I remembered a problem we had with some rental property a few years back, where a similar problem was occurring....lots of water being generated from the coils and the unit constantly dripping. Our AC guy at the time opened the unit and discovered the coils completely clogged with cat dander. He cut out the coils, cleaned it and put back in and prob solved.

    When I recalled this, I wondered if I might have the same problem? When I purchased the home a few years ago I noticed one day that the upstairs filter had been "sucked in" and not in position. Who knows how long that was in that position. So I took a gamble, and took apart and separated the coil section from the furnace and looked in. The coils were clogged solid with an accumulation of dust now turned hard and at least 2 or 3 mm thick embedded in the coils and on the surface!

    PLEASE SEE PHOTOS ATTACHED

    I vacuumed lightly to get as much as I could then used a coil cleaning spray and then pressure rinsed the coil until I could see straight through.

    The primary pan was in good shape with almost no rust at all but the drain opening was clogged with dirt, which is probably keeping the moisture in for long periods thereby producing the odd odor when running the unit.

    I unclogged the pipe, put the unit back together, retaped everything and turned on the unit.

    Odor is now gone, and for now it cools to 73 degrees within 20 min, whereas before the unit struggled to get to 78.

    New question:

    On the front side (warm air side before going through the coil) are 2 openings. One is for the drain pipe, which drains to the outside of the home I suppose as an emergency if the coil area should fill with water, but the other is just an opening through the metal work (please see photos)


    Hole (B) the drain pipe already has air pressure running through it, but what purpose is (A) and was wondering if I should seal it off?
    Attached Images Attached Images   

Page 1 of 3 123 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event