Premature Coil Failure and other ?

[egorss78]

Hi, looking for some guidance since the contractors in my area are all over the board on this one. We had the AC coil replaced in my AC unit about 3 years ago. Was told last week it is leaking again. We asked the service tech, why did it fail again already, he said that is the average life span of a unit in FL.

So we are at the position to just get a whole new unit AC unit installed or replace the coil again. We have had a couple contractors come out to give us estimates, and each one has a different answer to the coil questions. They range from Carrier makes cheap coils, to the AC unit was installed incorrectly. That one has caught by attention(and the only one that makes some sense). That sales rep said the unit ducting is incorrect and is causing moisture to form on the coils and degrades them quicker. Has anyone else seen this before?

Also out of many sales guys that came out to our house, only one spent the time to do all the calcuations for heat load etc. His estimate came back recommending only a 4 ton AC unit, instead of the 5 ton I have in the house. This person had some reservation about having to expand a door frame to house a larger unit, so we are not sure if his recommendation for a 4 ton is accurate, or he just does not want to deal with trying to fit a 5 ton unit(which we already have). Is it normal for a home builder to put in a larger than required unit?

Sorry for the long winded explination, just looking for some 3rd parties for guidance who are not looking to make $$ from me.

Thanks

[karsthuntr]

They guy that did the load calculation (as a general rule of thumb) is the going to be the most honest.

I would say 90% of the systems installed without a load calc. are over sized.

As far as the leak goes, with out knowing exactly where the leak is it would be very hard to determine a cause. I just replaced a Carrier system that had a leak in the indoor coil and I had just replaced it 3 years previous. So that tells me that coil quality is very poor, at least in my case.

The comment about the coil getting wet seems very odd, since its an A/C coil its supposed to get wet.

[skippedover]

There are issues at play that have even the most educated in the industry stumped. I spoke with a manufacturer today about an oil burner problem and was told that it's industry wide and they really have no idea as to why it's happening. So it is with the rash of coil failures we've seen in the cooling industry over the last 5 or 6 years. We do know about formicary corrosion, which is primarily the result of aerosols and other airborne corrosives in the indoor air. Carrier/Bryant has gone to tin plated coils in an attempt to get longer life. Believe me, it's not that it's 'cheap' coils. They offer 10-year part warranties on their products and it is not in their best bottom line interest to be cheapening the coils to the point of premature failure.

That said, virtually all of the companies are fighting the leak issue as well as the size issue. There is roughly double the amount of copper in a coil of today as was in the products of 15-years ago.

I'd recommend a couple of things to lessen your chances of another premature failure.

1. Get a tin plated coil. Accept no substitutes.
2. If you use any of the 'smell pretty' house sanitizers or aerosols, stop their use. They're not healthy for the HVAC system and they certainly can't be healthy for your lungs. Marketing is a wonderful thing only for the purveyors of the product.
3. Get a good quality, homeowner serviceable, electronic air cleaner. Maintain it religiously. Have the EAC sized properly so you don't suffer high static losses across it but having one you can service is very important to keeping the unit effective.

[bmathews]

What is the brand of the coil and the model number?

[egorss78]

What is the brand of the coil and the model number?

Not sure about the model, will have to check when I get home. The unit is a carrier brand, installed about 12 years ago.

[egorss78]

They guy that did the load calculation (as a general rule of thumb) is the going to be the most honest.

I would say 90% of the systems installed without a load calc. are over sized.

As far as the leak goes, with out knowing exactly where the leak is it would be very hard to determine a cause. I just replaced a Carrier system that had a leak in the indoor coil and I had just replaced it 3 years previous. So that tells me that coil quality is very poor, at least in my case.

The comment about the coil getting wet seems very odd, since its an A/C coil its supposed to get wet.

Thanks for the feedback, just assume a coil would last longer than 3 years, or everyone around me would be having coils failing. We are having another vendor come out and he will do a load calc, so at least I can compare those two.

[egorss78]

There are issues at play that have even the most educated in the industry stumped. I spoke with a manufacturer today about an oil burner problem and was told that it's industry wide and they really have no idea as to why it's happening. So it is with the rash of coil failures we've seen in the cooling industry over the last 5 or 6 years. We do know about formicary corrosion, which is primarily the result of aerosols and other airborne corrosives in the indoor air. Carrier/Bryant has gone to tin plated coils in an attempt to get longer life. Believe me, it's not that it's 'cheap' coils. They offer 10-year part warranties on their products and it is not in their best bottom line interest to be cheapening the coils to the point of premature failure.

That said, virtually all of the companies are fighting the leak issue as well as the size issue. There is roughly double the amount of copper in a coil of today as was in the products of 15-years ago.

I'd recommend a couple of things to lessen your chances of another premature failure.

1. Get a tin plated coil. Accept no substitutes.
2. If you use any of the 'smell pretty' house sanitizers or aerosols, stop their use. They're not healthy for the HVAC system and they certainly can't be healthy for your lungs. Marketing is a wonderful thing only for the purveyors of the product.
3. Get a good quality, homeowner serviceable, electronic air cleaner. Maintain it religiously. Have the EAC sized properly so you don't suffer high static losses across it but having one you can service is very important to keeping the unit effective.

Great comments, saw one of the quotes we got was for a bryant system, and it looks like I can get tin on those coils. Also saw trane is moving to a aluminium coils, any comments on those compared to tin.

I am just leary of installing another carrier/bryant system after the failures we have had with our existing carrier. My understanding is bryant and carrier are pretty much the same company/parts.

Thought replacing a AC system in my house would be pretty straighforward, but each contactor is giving different opinions on what is causing the coil failure and which system I should get installed(4 ton/5 ton)

Random other comments, one vendor recommended we replace the copperline that runs from the inside unit to the one outside. Other two said they will flush the existing one out with nitrogen. Any thoughts?

[precision hvac]

Many contractors will simply bid like for like when it comes to size. If you have a 5 ton now- that's what the replacement bid will be. Some will look further.
Maybe you built a patio across the entire back of house & all the windows are shaded now.
Maybe you upgraded the windows to double pane.
Maybe you upgraded insulation

All these things will effect the size.

Linesets- we replace when we can, flush the ones that are difficult to replace. Always a good idea to replace the lineset.

[egorss78]

Many contractors will simply bid like for like when it comes to size. If you have a 5 ton now- that's what the replacement bid will be. Some will look further.
Maybe you built a patio across the entire back of house & all the windows are shaded now.
Maybe you upgraded the windows to double pane.
Maybe you upgraded insulation

All these things will effect the size.

Linesets- we replace when we can, flush the ones that are difficult to replace. Always a good idea to replace the lineset.

Thanks, no upgrades to the related to size/insulation, so I think you may be right, they are just bidding the current size.

The lineset is between the floorboards(2 story house), so to replacement it requires running the line across attic, out the side and down 30 feet. Do not like the idea of a pipe hanging off the side of my house, so I am leaning towards asking them to clean the existing one out. Figure if there is a problem with it later, then can run the line then.

[billygoat22]

I see a lot of leaky evap coils in spring, when people switch over to cool mode. the coil issue is hit or miss from house to house. like others said, formicary corrosion, pitting from offgassing of new materials and even the chinese drywall issue.

trane and goodman both have al coils now.

[TOOMANYHACKS]

We are in the process of getting a new split system put in to replace our dead 20 year old Trane XL1200. Trane/An Standard has had Alum. coils for years since our old system has an Alum. coil and we never had a leak or needed any r-22 added when it worked.

I noticed that two of the quotes we got for a Trane xl15i included a 4TXCC042BC3HCA which is their TRANE AlumaTuff™ ALL-ALUMINUM COMFORT™ COILS.

I highly recommend the aluminum coils over the copper/ alum ones. Several people I know had to have their non all-aluminum ones replaced.

[egorss78]

We are in the process of getting a new split system put in to replace our dead 20 year old Trane XL1200. Trane/An Standard has had Alum. coils for years since our old system has an Alum. coil and we never had a leak or needed any r-22 added when it worked.

I noticed that two of the quotes we got for a Trane xl15i included a 4TXCC042BC3HCA which is their TRANE AlumaTuff™ ALL-ALUMINUM COMFORT™ COILS.

I highly recommend the aluminum coils over the copper/ alum ones. Several people I know had to have their non all-aluminum ones replaced.

Thanks for the advise, we have decided to get a trane system installed tommorow. Hoping this will correct the issue for a long time(10 years at least).

[Keith73]

Maybe I overlooked it but, I am assuming because you are in Florida (FL) that it would be the outdoor coil (condenser). Salt air will destroy these coils quickly unless you "pony up" for the ones that are rated for that condition. Some warranties have exclusions (as I understand it) when installed in coastal climates.
Just my two cents worth.

I saw lots of comments about evaporator coils also, that could be a different issue!

[amd]

Are the all aluminum coils any good?

[amd]

3. Get a good quality, homeowner serviceable, electronic air cleaner. Maintain it religiously. Have the EAC sized properly so you don't suffer high static losses across it but having one you can service is very important to keeping the unit effective.

Why? I'm sure they're great for the submicron particles when properly maintained (smoke, etc.), but how can an eac prevent a coil from leaking?

A media filter is the best option because eacs don't get maintained. cleaning every 2-4 weeks is required.