New Coil?


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Old 05-18-11, 05:22 AM
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New Coil?

Hi guys-

Question/thoughts on an issue with my central a/c. I have owned my house for about 2 years. The first year I lived in it I had the freon filled in it 3 times, by 4 different hvac guys. The first time it was filled it lasted about 1.5 months and the outside unit was cleaned. The 2nd time I hired a different guy because I was upset the first guy didn't "fix" the problem. The 2nd guy was looking at the copper tubing outside and said the leak was there and "fixed" it. He also said my unit was way too big and my ducting was all wrong and I needed to replace everything. Ok. Didn't really believe him because even though this is my first house and I don't know much, he seemed odd in other ways I didn't really trust his opinion. 1 month later problems again. I called the first guy back because of issues. He told me that the 2nd guy put way too much freon in the system and it needed to be taken out. OK. Well, he couldn't do it that day and would be back. Multiple calls and didn't come back. On to the 3rd guy. He came took a look at things and said everything should be ok once he gets the freon at the right level. Great. This was Sept of 09.

Everything worked great until the first time I turned it on this year. Wasn't cooling house again. Called out the 3rd guy. Freon is down 1#, or about 15%. This time he tells me that I should replace the coil inside that sits on top of the furnace. He said he was 99% sure it was leaking in there. He also said by the looks of it (outside housing of coil) that it is extremely old and could possibly be from when the house was built??? House was built in 1973 and the unit outside is a Ruud build date of 1993.

So finally on to the question. I asked if I needed a new a/c unit and he said that even though it is a little big for the house (2.5 ton, he recommends a 2 ton), that the thing that would fix the whole issue would be to replace the coil. $600 ($300 part, $300 labor.) He said that by replacing the coil he was 99% sure that I wouldn't need freon for a long, long time and that the new coil would be much more efficient. He did say he could put some kind of "stop leak" in the unit for $75 but doesn't like to use it because it can foul up meter readings if the unit loses freon again.

So to make a long story longer, what are your thoughts? The only parts(as far as I know) that were checked for leaks was the copper tubing running for the unit up to the house. Could it be leaking in the tubing running through the basement to the coil, or do you think he is right and to get the new coil?

Thanks for help & suggestions!
 
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Old 05-18-11, 07:27 AM
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A leak search needs to be done to determine the exact location of the leak. The quoted repair sounds very cheap. I do NOT recommend stop leak! Your outdoor unit is 18 years old and average life of an ac in the us is 12 - 15 years. I would consider replacing the whole system. Now, as far as sizing goes, you cant just look at a house a determine the size of unit needed. A manual J load calculation needs to be done to determine heat loss to size the equipment properly.
 
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Old 05-18-11, 07:40 AM
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Thanks for the reply hvactechfw. I mis-typed. The a/c unit is actually 2003. So 8 years old. The issue I'm having is wondering why nobody will do a search for the leak inside of the house. Not sure if they are just lazy or what. The guy I'm using now is kind of a family friend. My dad has know him for 20+ years. He is very reasonably priced and seems like a good guy. Just don't know what to think about him not looking for the leak and assuming it's the coil. Is it possible to look inside the coil housing to determine a date? Also he noted rust stains in the drain tube coming out of it. Said most likely it is rusted inside and could rupture and take out the furnace electronics. I guess my dilemma is get a new coil and trust the family friend or get another opinion. I'm not sure why 3 different guys can't pinpoint the problem.
 
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Old 05-18-11, 07:48 AM
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A leak search should be done with an electronic leak detector. The good ones are very expensive and some techs dont have them, but the only way to determine where a leak is is using one. Soap bubbles often dont find leaks in the middle of coils. MOST of the time leaks are found in the indoor coils but that doesn't mean all leaks are found there. As far as rust goes..... You will most often find signs of rust water in drains due to the composition of the coils..... They are made of aluminum, copper, and steel. The steel rusts due to oxidation caused by condensation on said parts. Ive seen rust in the drain lines of a 1 year old system. If the evap coil drain pan is made of metal then that is not good. They used to be made of steel and are now made of a polymer so that they dont rust out and leak onto what ever is below them.
 
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Old 05-18-11, 08:19 AM
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Thanks again hvactechfw. Good information. I guess maybe I should ask him if he does replace the coil if he'll warrant that there will be no more leaks and if there is then he needs to fix it free .

1 more question. On average how long do coils lasts? If it is 8+ (who knows) years old, do people generally wait for it to completely stop working before replacement?

Thanks again!
 
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Old 05-18-11, 01:25 PM
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It used to be that coils lasted for 20 years.......Now it depends......Manufacturers rifle the copper tubes in the coils to make them more efficient, this is typically the reason why newer coil fail so often. The rifling process thins the copper tubes. Homeowners vary with their decisions to replace their systems. This is because every home and every financial situation is different. Most homeowners either wait until they have a breakdown and then a tech lets them know how bad the system actually is (usually from lack of maintenance), or those who have regular maintenance down by a trustworthy company tend to replace it before the system is completely broken down because together with the technicians assessment and the homeowners understanding they can agree about who the system has been working, the repairs that need to be made for longevity, the age of the unit, and the efficiency of the unit. Its really depends on the situation.
 
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Old 05-18-11, 03:24 PM
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Thanks again. Very insightful! I guess it does make sense to replace it if in fact it is the culprit. The age of it, along with energy savings and frequent refills makes me think it is time. Now you have me worried about the new one not lasting as long
 
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Old 05-18-11, 03:34 PM
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have it maintained yearly.... thats the best thing you can do to ensure a long life of your a/c
 
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Old 05-18-11, 05:46 PM
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1 more question for you please. You mention to have it maintained yearly. When I had the guys over to fill the freon, each 1 told me to keep the outside unit clean and use a hose to clean out on the exterior of it (careful of the electronics). Never has anything on the inside really been inspected beyond the drain line. Are they supposed to be cleaning out the coil also?

Thanks again!
 
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Old 05-18-11, 07:07 PM
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the evap coil should be checked... The outdoor unit needs washed out with water from the inside out. Electrical components checked. Amp draws checked. Filter checked. Blower checked. Drain line cleared. And some other items im just not remembering right now.
 
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Old 05-19-11, 12:08 PM
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sounds like you are getting inexperienced technicians. It takes time to find leaks, guessing that its in the evap coil is a shot in the dark he could get lucky though. If I can't find the leak with bubbles and leak det. I isolate both parts evap and cond. for a few days to determine exactly where the leak is. Anything short of that and chances are you will have more problems.
 
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Old 05-19-11, 02:14 PM
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Thanks for the replies guys. 2 of the guys are 1 man operations and the other guy is the owner and had like 5 or 6 employees. My new thought is to hire a "big" hvac company to come out and do a thorough cleaning and see if they can find the leak. If it is determined that it is the coil, I'll just get the last guy to come and do it for $600, since it seems like a "deal".
 
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Old 05-19-11, 07:36 PM
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All the coils should be cleaned before charging. You can't get proper charge with dirty coils. Sounds like u need another tech
 
 

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