Water tends to leach off a bit of copper... that sometimes looks green...

Some copper ore... is greenish

 

Bay a pic further away

 

from further away:

 

does this leak out from the coil inside?

 

id say the fat black line is sweating , dripping onto the little copper line

Do you replace you air filters every few months ?

What MERV rating are you using on your filters?

 

I use Filtrete Premium Allergen Bacteria and Virus Air Filter 1900 MPR MERV 13
I don't change every month. But 2-3 months.

 

You couldn’t pick a worse filter for that system.

 

why? And what would be better?

 

Filtrate filters have small print that they only work in ductwork systems designed for the restrictions they add.

Use the basic low cost filters, change them every 30 days and you are good to go.
If you want better filtration, you need a media filter with high surface area. 3” to 6” depth, and sized to prevent duct loss in the equipment.

 

As to your original question, the black line appears properly sealed and shouldn’t be leaching copper.
Has the ac been replaced since the furnace was? I don’t see any leaching on the coil box.

 

Just to be sure, you referring to green circled area?

BTW: is the black line going inside, is not terminated on the outside? The grey putty is a bit spotty.

 

yes, the outside compressor and the AC coil have been replaced about 2 years ago. Before, I never noticed green stains

 

Looking closer at the insulation, it appears the installers taped the cut insulation in sections, but left gaps between the tape.
The insulation needs to be airtight, seamless.
Look it over carefully, and verify there is an open seam.
When the cold line gets warm moist air around it, moisture will collect, and leach the copper from the line, it will dribble downwards, and show up as a stain on the furnace.

You should be able to tape up the insulation seam, and be protected from further leaching.

 

if you put too thick of a filter in there , which slows down the air , which makes the air colder , which makes your Grilles sweat , and makes other parts sweat if they arent insulated enough

Use a Merv 8 if you really want , bur Merv 5 is adequate

 

BTW. this Filtrete is rated at 1025 CFM
When I look at a Honeywell MERV 8 it states 1390 CFM


Out of curiosity, what is a good CFM rating for my furnace?

 

I had my AC and cooling coil replaced about a year ago.
Now, I am noticing the green stains on the AC unit. What is causing them? A refrigeration leak? Should I be concerned about it?

It's not a refrigeration leak. Moisture, probably condesation from the suction line, has been dripping onto the bare copper liquid line and then onto the furnace. The water strips a smidge of the copper off of the liquid line and deposits it on top of the furnace when it dries out. The condensation might be working its way out from under the insulation, or its possible that your AC froze up at some point and then dripped when it thawed.

I use Filtrete Premium Allergen Bacteria and Virus Air Filter 1900 MPR MERV 13
I don't change every month. But 2-3 months.

Don't. They tend to restrict airflow, especially if you leave them in that long. They could also cause your AC to freeze up. Don't pay more than $5 for a filter, stick to MERV 8 or less.
If you have dust or allergy problems I'd recommend a duct cleaning and having a media air cleaner installed.

I'm not a fan of how they installed your coil. Steel clamps on the liquid line are a no-no and the line shouldn't be touching the flue pipe, ESPECIALLY if water drips on it. The liquid line could develop galvanic corrosion and begin leaking refrigerant. Have your service company move that liquid line next time they come out to clean your AC.

 

Thanks. I will downgrade the filter.
I imagine retrofitting a "media air cleaner" will not be that easy? Given the 1" space between duct trunk joining up with the furnace.

 

Well worth the expense!

 

Any competent installer should be able to handle it.

 

Here is my setup.

Unless, I could do something like this angled product?
https://jacksonsystems.com/product/...-1442305525416:pla-295531751190&hsa_kw=&hsa_mt=&hsa_net=adwords&hsa_ver=3&gad=1

 

I think I am sold on the idea. Just not sure how it will be accomplished.
will I need a 90 degree module?
https://jacksonsystems.com/product/...-1442305525416:pla-295531751190&hsa_kw=&hsa_mt=&hsa_net=adwords&hsa_ver=3&gad=1

Moving the whole return trunk would seem major work

 

Increase the duct, install the housing, decrease the duct size.

Turning veins will help.

 

back to my original stain issue. A beautiful summer day in Chicago made me turn on the AC. And yes the condensation is coming out at the bottom where the black insulation meets up with the putty. I put black insulation tape around it. Will see if I get it dry.

I am not happy with the work the installer did. The black insulation sleeve is pushed onto the exhaust pipe. More, the copper return is also touching the exhaust.