Bad evaporator coil/cores???

[Katkt]

I originally posted this question/comment up in the residential geo-thermal forum, but wasn't getting any response.

I'm getting ready to have the third evaporator coil/core in as many years, replaced in my WaterFurnace right now. Leaks have been verified either with a sniffer, or visual oil residue
I've been told that this is an industry wide problem(by both the contractor and WF).

Are crappy evaporator coils/cores an industry wide problem, or is this something that is plaguing WF?

Its a 4 ton closed loop system, that works great except for this.

Our previous home had a Carrier gas furnace and AC that went 14 years without a problem

[Swampfox]

Yes, chronic problem in the industry, and the manufacturers dont seem to be doing much to address the problem unfortunately.

3 in 3 years is a bit extreme though, I would look for some environmental issues in your home that may be contributing to these failures, was the house built in late '05 or around that time? do you have the dreaded drywall imported from China?

[Katkt]

Thanks for the reply.

The home was completed in 01.
This unit sits on a slab in an environmentally controlled space under the home. We run a dehumidifier in the crawl space, and the exhaust from our central vac is discharged in this area. Its better then most basements except for the gravel floor over poly. The temps remain in the seventies in this area, and the humidity is probably never over 65%.
The first unit we had was ruined by Ivan, in 04. The water and waves were deep enough to breach the ground under the footer. This was repaired, cleaned up and returned to pre storm conditions. We didn't have any problems with the evaporator coil in the first unit.
The second(this unit we have now), was installed in the fall of 04, and the first evaporator coil was replaced in less then 6 months. The second was replaced in the spring of 08, and we are ready for the third now.

[claymoore73]

I would start with the environmental issues with the house. In Florida when people have well water that has a high sulfur content that can eat up Evap Coils quick. Same issue with the Chinese Drywall and the high sulfur content. When they take the coils out is the copper black in color? The only thing I have found that extends the life of the coils is have them treated or dipped before install. This extends out the life several years.

[Katkt]

Its a closed loop system, that was filled with tap water.
The only coil thats having problems, is the one that the refrigerant circulates in, where the air enters the unit from the air return duct.

There is no exposed unfinished drywall in the home. The walls are painted with an oil based primer, and two coats of satin latex paint(I applied the paint). The floors are tile and bamboo. The home was completed three years before this second unit was installed.

[claymoore73]

What kind of water do you have in the house for showers, washing dishes and so on? Is it well water? Do you know if the water has high sulfur content?

When you take showers, wash dishes, Clothes this all puts moisture in the air and when the AC is running this moisture accumulates on the evap coil to drain outside. When this collects on the Evap coil the sulfur will deposit on the copper and cause it to rot. Then pin holes will start in the coil and then needs replaced. This will go on over and over no matter who makes the coil. Even if you put in an aluminum coil it may last a little longer, but will do the same to the aluminum. The only thing I have used that helps extend this a few years is applying a product to a new coil call "Coil Guard". You wash the new coil with soap and water let it dry and then apply the product. The best way is to have the coil dipped or coated professionally. The only other option you have is a very expensive water system that will treat the water supply for the house.

This is all speculation without seeing the coils. Some tell tale signs are a black colored coil.

The Chinese Drywall issue doesn't matter if it's painted or not. If built in 2001 I think you would be safe from that.

[dash]

tightly built homes have the most issues with "formicary corrosin"

A quick search should get you some info on it.

Bring in some fresh air to dilute the VOC's and other stuff that's likely causing the coil leaks.

[Katkt]

Gentlemen,

Thankyou very much for your help. When I was researching the "formicary corrosion", that Dash mentioned, I found this link.


http://hvac-talk.com/vbb/showthread.php?t=172866


Its funny, because I heard the state senator down here(Bill Nelson) trying to cash in on the health aspect of air quality that can damage an AC coil. I think the guy is a blathering opportunist, but hey its all about timing.


That Trane and Carrier are onto a solution, is the type of information I was looking for.
My feeling about this, is along the lines that Swampfox mentioned. It was eluded to in the attached link also. It seems that as long as the units were flying out the door during the big building boom(that came crashing down recently), everyone was rolling in the dough and patting themselves on the back, instead of addressing the issue.
People are staying in their homes longer now, and equipment failure is becoming a headache.

I can see companies persisting with the cheaper copper coils, and rolling the dice that they wouldn't have to deal with a warranty issue. Kind of the proverbial "tail light guarantee".

Just some additional info about our home. We don't use well water, All of our household water is city/treated/ comes through a meter at the street water. The "aldehydes" mentioned in the other link, seem like they could be as big or bigger problem then "sulfur". "Aldehydes" are big components in adhesives etc. used for plywood and other stuff.
I don't believe I'd classify our home as super tight. I'm a carpenter(not a builder:p), and am aware of the stale air issues that can arise from homes without adequate air exchange. The second floor ceiling, is 1x6 TG. The ceilings are vaulted, with dormers and although it looks good, and is extremly tough compared to sheetrock, it allows alot of air to move thru.

Hopefully, the folks at WaterFurnace have something going with their coils. The attached link, was from mid 08, and Trane and Carrier where getting the copper out even though it sounds like they were kicking and screaming.

Thanks again for the help. I'll check back and give ya'll an update when the dust settles. I'll look over the coil for discoloration, and if theres anything interesting I'll share it.

[Katkt]

I'm a bit tardy getting around to adding this to the thread, but here is what happened.
It took close to four weeks to get the new coil from Water Furnace. Its been in and operating for a couple of months now.

Just a refresher, this is the third coil in this unit from fall of 04 until this summer.

The original coil that only lasted a year....less actually, the unit was installed in October, and the first coil was found to be leaking in the spring when things warmed up enough to require serious cooling........ was your standard run of the mill copper tube coil.

The second coil....and I had forgotten this until I saw it when it was removed,.....had some sort of epoxy ?????? black shiny finish on the coil. The AC contractor had mentioned it, when it was installed. I'm guessing that this was Water Furnace's first attempts at dealing with what they thought was a problem with "formicary corrosion".
When the core was removed, it had numerous areas that showed oil leakage on the surface/face of the core.
My first impression, was that the problems looked to be more along the lines of a badly made coil, rather then "formicary" issues.

The coil that was installed this time, appears to have been made of either aluminum, or an alloy of some sort. This is the third generation, and I have high hopes that it will out perform everything to date. I'd imagine the folks at Water Furnace, are hoping the same thing.

The folks at Water Furnace seemed to weather the storm as well as could be expected. The young lady that was hired to deal with customer complaints, was a very optimistic and sincere person, who was only a little put out by my suggestions that the company's efforts to date, were less then substantial. I suggested, if more money had been spent on R&D for the coils instead of bonus monies for the upper tier, the problem might have been solved sooner.

In the end, I vented, Water Furnace provided a new improved coil, and the installation went without a hitch.

It's great having the benefit of the ground loops to provide cooling in a pinch, but the higher utility bill wasn't fun. All things considered, I'd be hard pressed, to go the GEO route a second(third?) time. The unit and the new coil, will have to run flawlessly for the next 15 years, to ever salvage my reputation with my wife for choosing the GEO a second time after Ivan wiped out our first WF system. She was ready to simply go with a conventional system, that would have been a third of the replacement cost. Not having an outside unit is a plus where we are, because of the wear and tear on them and the general lack of eye appeal and noise of the units running when people are outside, in what is for us, a very quiet neighborhood.

Thanks for the info that was shared.