A/C Coil Fins missing in places

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  #1  
Old 08-20-07, 08:29 AM
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A/C Coil Fins missing in places

Moved into a house a few months back and in two of the lower corners the coil fins are gone and blue green corrosion is on the ends of whats left of the good coils. AC/C seems to be running and blowing cold air just fine but how long will this last?

There were weeds/grass growing around the unit almost as high as it was. Think it is better/cheaper to get it inspected or replaced this fall or just wait until it dies?
 
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  #2  
Old 08-20-07, 09:17 AM
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Sounds like dog urine. This will eat up the aluminum fins. The result is high head pressure and increased power consumption. Since the fan pulls air through the coil, a large section of missing fins will allow more air to bypass the remaining fins. Combine this with loss of surface area (missing fins), you can easily get into trouble.
If only a small percentage of fins are missing, you are probably OK assuming the rest of the coil is clean, allows air to pass through it and there are no freon leaks.

The only real fix is to replace the condensing unit or just the coil if the unit is fairly new.
 
  #3  
Old 08-20-07, 10:01 AM
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It is just shy of 5 years old. The neighbors did say that the previous owners had a dog they never let in so that was it im sure. It is about as big as my hand (on each side) and I think I can see 4 tubes. As for how well it performs I have no idea. Just moved to this area and we don't have to run it a lot since it isn't that hot. I do have to replace the insulation around the line running into the house. That is all chewed up and now I know why.

Thanks
 
  #4  
Old 09-25-07, 07:34 AM
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Well I had decided to replace it, but then I got to thinking. Jim-connor, you mentioned that you can replace the coil. Is there a rough estimate on cost of a new coil. It is a Luxaire 3.5 ton which is about 5 years old. I've been trying to do some research about it, but it doesn't look like there is much out there on this. Model is a HABA-FO42SE.

Thanks if anyone knows.
 
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Old 09-25-07, 10:01 AM
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Post a pic if you can. Most likely from your description the unit is just fine and does not need replacing. Have the coils cleaned and you should be good for many years. All the fins do is help distribute the heat from the tubing as long as air is flowing across the tubes themselves you will still get a percentage of heat transfer. My favorite saying is IF IT AINT BROKE DONT FIXIT
 
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Old 09-25-07, 10:21 AM
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Like said 5 years old and it runs good . Let it alone till it dont work. Id just wash out the coil good there.
 
  #7  
Old 09-25-07, 10:50 AM
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Well it keeps corroding and growing it has easily doubled in 3 months. It still blows cold but it can't be working as efficient and I don't want it to burn out or cause other problems from running to much.

Originally Posted by Ed Imeduc View Post
Like said 5 years old and it runs good . Let it alone till it dont work. Id just wash out the coil good there.
 
  #8  
Old 09-25-07, 11:09 AM
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I will post one tonight. Thank you for the suggestions.

Originally Posted by Mr Fixit View Post
Post a pic if you can. Most likely from your description the unit is just fine and does not need replacing. Have the coils cleaned and you should be good for many years. All the fins do is help distribute the heat from the tubing as long as air is flowing across the tubes themselves you will still get a percentage of heat transfer. My favorite saying is IF IT AINT BROKE DONT FIXIT
 
  #9  
Old 09-25-07, 02:39 PM
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Pictures of corrosion

This is one corner (click to see larger)



This is the other corner



I know it is hard to see but this is what it looks like inside behind the holes.



Thanks,
Dan
 
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Old 09-25-07, 04:15 PM
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Wow now that puppy has some potent weewee. Apparently he is still whizzing on your unit if the spots are growing and your new unit would no doubt suffer the same fate shortly. You will have to install a fence or some kinda barrier around your condenser to keep the pooch away, or of course you could take him on a hunting trip and forget to bring him back LOL. Right now start taking the water hose and washing the units coils daily to keep the urine from eating up the fins. And see if you can figure out which neighbors puppy is doing the deed, maybe they can keep him in tied up or penned or something. That damage is severe and will affect the performance of your unit especially during peak temperatures when the unit needs every square inch of fin it can have to perform its heat transfer operation.
 
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Old 09-25-07, 05:28 PM
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You could ride it out, you may not be it's peek SEER. When we moved into our house, we had the same thing on our coil. When I had the new furnace bid, the dealer said he could get me a new coil.. Come the day of the install, the coil was on back order, and the price of it has gone up alot, so he just got me a new Trane instead for the price of the coil.
 
  #12  
Old 09-25-07, 05:34 PM
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Well the dog is not doing it anymore. This was a previous owner of the house that had one. It also chewed the insulation around the copper piping.

My house is fenced and I have female dogs. My neighbors all have the same unit and a few are in the same shape. Only I took a hose to mine to clean it and just washed it all away.I am guessing it was wee wee from an earlier post. That is why I was wondering if it was fixable or just get a new unit.

I've looked at the big names and then I read about American Standard, Gibson, and one of the installers I spoke with mentioned Ducane. I've been researching and it seems the big names are good but your of course paying more for the name. Then these other brands looked good also so now I am just looking at getting about 1/2 a dozen quotes for a new one if it isn't fixable.

On a side not I did have one quote and it seemed to good to be true. I have a 10 seer unit now and he said he could give me a 13 seer Carrier for $2600. He didn't even come inside though to look at the air handler so not to sure about him. I know a good contractor is what makes the difference.
 
  #13  
Old 09-27-07, 07:50 PM
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Well I think Im going to go "hybrid." A heatpump isn't to much more and should save me some money in the winter. Southern MD doesn't get to cold and I have a gas furnace. Hard to decide if I want to change it out too and go with a 2 stage variable furnace.

Haven't settled on a brand yet but I like the AS dealer here. Now to "interview" the rest.
 
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Old 09-27-07, 08:21 PM
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how old is the furnace?

If it's a few years old, and 90%, then I'd keep it, and upgrade to a heat pump.
 
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Old 09-27-07, 09:44 PM
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Why dont you go and check out and compare fuel cost for where you live http://warmair.net
To see if a heat pump is good for you there. If it cost more stay with just the gas furnace and go for a seer of 15 on the AC. You can get a tax credit from the IRS on it
 
  #16  
Old 09-28-07, 05:36 AM
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Thanks for the calculator link that will be helpful. Do you know how what number I would plug in for the efficiency of a heat pump. I know it is not the SEER, but is it the HSPF? If it is then it looks like a heat pump would be great (with a gas furnace for below 40.)

Im using .01166 for the Gas Cost and .0971 for the electric cost. Im not sure what my 5 y/o Luxaire efficency is but the heat pump HSPF is up to 9. So I played with 85%-95% for the furnace and 5-9 for the heat pump. The heat pump was less then half of a furnace at 95% for furnace and 5 for HP.

Am I doing my calculations right? If gas were to fall in price sometime in the future to what it was 5 years ago then it would be a closer battle.
 
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Old 09-28-07, 09:47 AM
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if your furance has the white pvc vent, then figure 90%.

If it's metal with a small fan to remove the exhaust, then it's 80%.

Depends on what model of heat pump you are looking at, you kind have an ideal??
 
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Old 09-28-07, 10:26 AM
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Im looking at the American Standard/Trane lines. I had another great contractor come in today. The more I talk to them, read on here, and learn on my own the better it gets.

If my furnace is getting around the 90% efficiency (it is PVC) and since it is only 5 years old I will most likely get the American Standard Heritage 14 or TRANE XL14i plus it may need a matching coil. They say I don't have an expansion valve.

If I were to replace the furnace also then I would look at the 2 stage systems with a variable speed furnace. The money I save on a furnace I will use for one or all of my wish list items. In order of what I would like best it is.

1. Dual Zone (easy enough to put in with the way my ducts are)

2. Whole house humidifier.

3. Air cleaning system. Two dogs, and I have allergies, although someone mentioned a spray on product in another thread. I still have to research this idea more. Maybe just go with the AprilAire filter or like.

My house is only 5 1/2 years old so my copper pipe is the right size and in good shape. I also have at least 5 wires running to my outside unit so no need to that.
 
  #19  
Old 09-28-07, 08:53 PM
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Well once again reading this great forum and using the search function has changed my thinking. I thought making the 2nd story a separate zone would keep it cooler and save money. Now I am not so sure. A few mentioned just closing the vents on the lower level. That works, it can be a pain but its not hard.

Another post mentioned running the fan non stop. I heard bad things about doing that in the cooling season. Something about not giving the moisture time to be removed from the coil after the AC shuts off.

So the answer seems to be find a thermostat that has a setting for a fan that cycles on/off more often then just when the AC comes on. That makes sense to me and surely will be a lot cheaper. Of course now its back to research more.
 
  #20  
Old 10-13-07, 09:52 PM
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Well found the energy sticker today when I went to turn the furnace on. It had a 93.4% AFU on the ole Luxaire. I just wish it had a variable speed fan. Heat pump should be installed in the next two weeks. Now I just have to talk to the HVAC guy and see what the correct balance set point is. I keep hearing 40 degrees, but from all the reading I've done that can't be right. Once I get the load calc done that should help.

The only thing I don't know about is the humidifier. I decided against the steam. The cost was too high so I am going to go with a Aprilaire either the 700 of 400. I may wait and see how the humidity is since this is my first winter here.

Thanks everyone for all the help. Its been a real eye opener and money saver.

Originally Posted by Jay11J View Post
if your furance has the white pvc vent, then figure 90%.

If it's metal with a small fan to remove the exhaust, then it's 80%.

Depends on what model of heat pump you are looking at, you kind have an ideal??
 
  #21  
Old 10-14-07, 06:32 AM
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Yeah, give it a winter and see how your house behaves over the winter.

I've seen heat pump here in MN run down to the teens. You can get a nice Honeywell T-stat like VisionPro or IAQ t-stat, and will automaticly switch over to back up if it's can't keep up.
 
  #22  
Old 10-19-07, 06:13 AM
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I got the results of the manual J and surprise surprise it said a 3 ton unit should go in not a 3 1/2 like what was there. Wonder how much more efficient it will be with just a 1/2 ton difference?

If it wasn't for you guys I would have never known to ask, THANKS!!
 
  #23  
Old 10-19-07, 09:02 AM
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I should have posted the results but it was too late to edit it so here is another post.

Outdoor Unit Model Number: 4TWX4036B1

Indoor Unit Model Number: 4TXCC037BC3

Furnace model that was used was *UX1B080A9H3 but thats not my furnace. I hope it is similar. Im not replacing the furnace. I won't be at this house for more then 10 years.

Cooling Capacity (BTUH) 35400
EER 11.70
Seer 14.00
Heating Capacity (BTUH) @ 47 degrees 30600
Region IV HSPF Rating 8.50
Heating Capacity (BTUH) @ 17 degrees 19300


Does this look normal?
 
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Old 10-19-07, 06:59 PM
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Sounds like you are getting a good set up.

Do you know what you are getting for T-stat?
 
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Old 10-20-07, 06:49 PM
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Ya the 802, now how come the btu heating seems so much lower then some other 3 ton models? Maytag for instance was a lot higher, Gibson even looked a bit higher.
 
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Old 10-20-07, 07:14 PM
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Originally Posted by dn0121 View Post
Ya the 802, now how come the btu heating seems so much lower then some other 3 ton models? Maytag for instance was a lot higher, Gibson even looked a bit higher.
Honestly, I don't know why it's lower then some of the guys?

You know if they are planning on using the outdoor sensor?
 
  #27  
Old 10-20-07, 08:00 PM
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Yes he said they will.
 
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