What to do about my AC system or HVAC system in general? Likely leaking evaporator coil.

pudgemail

My AC system has a refrigerant leak, likely in the evaporator coil. Refrigerant has been added twice and it continues to leak. Both a nitrogen leak test and UV dye test have been performed with the most likely leak location as the evaporator coil. The evaporator coil also shows signs of corrosion. The compressor seems to work though its contactor might be failing.

House and current system:

Location: Chicago, IL
Size: ~1400 square feet

Insulation: The house is from the 1950s and the wall insulation was upgraded in the 2000s. There are a lot of double pane windows.

Duct sizing: I think the ductwork is sized for ~1000 to 1200 cfm. It probably has some leakage and I can definitely see some gaps in the ductwork in a few places in the basement.

Condenser: International Comfort Products, N4A336AKB200, 3-Ton, Manufactured in 2012

Evaporator: International Comfort Products, EDD4X42LA2, 3.5 Ton, Manufactured in 2011

Furnace: International Comfort Products, C9MPX100L20A, 100,000 BTU, 92% AFUE, D-size width, single stage, constant torque blower, manufactured in 2011.

Thermostat: Ecobee 4

The current furnace is likely considerably oversized. It is 100k BTU and should more likely be 60k BTU. The furnace hasn't given me any problems so far. The return plenum and filter boxes are likely a little undersized.

The "D" size width of the furnace is problematic in terms of fitting a new evaporator coil and will likely require some ductwork to adapt to a 454B 3 ton evaporator coil.

I have gotten quotes from a number of HVAC contractors for four potential options. Most of the quotes came up with roughly similar sizing with heat loads of 60 kBTU to 70 kBTU and cooling loads of 30 kBTU to 36 kBTU. This matches pretty well with my rough checks using online Manual J calculators, though it does seem to depend heavily on the assumptions I make about the wall and attic insulation.

There are four overall options that I see.

1)Replace just the 410a evaporator coil and add refrigerant.

2) Install a new AC system (condenser, evaporator, etc.)

• The sizes range from 2.5 Ton to 3 Ton condenser units paired with 3, 3.5, 4, or 3 to 5 Ton evaporator coils.
• The evaporator coils will need to be adapted to the D width furnace.

3) Install a new AC and a new furnace

• Estimates covering a wide range of high efficiency furnaces. Some with 2 stages and variable speed blowers.
• The sizing ranges from 60 kBTU to 80 kBTU for the furnace.
• The higher end quotes also typically include modifications to the return plenum, a furnace box, and a larger filter box.

4) Install a dual fuel heat pump and furnace system (theoretically I could just get the heat pump I guess and keep the existing furnace for the time being).

• If I go this route the systems I am leaning towards are either a Bryant Preferred Crossover (really made by Midea) or a Bosch IDS Premium.

Any recommendations on what I should do?

Option 1, doesn't make much sense to me given the cost relative to a totally new AC system especially given the condenser is 14 years old and there may be other leaks. My concerns with only replacing the AC is that I still have this mismatched furnace that the evaporator coils must be sized to fit. If the furnace needs to be replaced in the future am I just continuing the mismatch. Will I likely then have to swap out the evaporator coil? The new furnace and AC or dual fuel heat pump and furnace is tempting because it would correct the furnace sizing and mismatch issue and if I went with a variable speed blower would likely have more comfort but it is almost double the cost of just replacing the AC.

What would you do? Any thoughts on the situation or other things I should consider?

I added some photos of the evaporator coil in the following Imgur album.

https://imgur.com/a/AWBlXM4

Jamie Hall

Please remove the price quotes from your post, in accordance with the site rules (we don't have many — but that is one).

EBEBRATT-Ed

@pudgemail

Please delete your pricing as it is not allowed on this site.

With 14-year-old equipment you are at the crossroads. It's not that old but most will not even try and repair it.

It would be nice if the service tech could pinpoint the leak. "Likely in the evaporator" doesn't help. They are too lazy to look.

Have them find the leak and then determine if it is repairable or not. Without knowing that everything is just a guess.

They want to sell equipment.

If you replace the equipment do a manual J so you get the right size equipment.

Mr. hall beat me to it as I was typing!!

pudgemail

Thanks, I edited out the pricing information. I have contacted five companies with good reputations and none seem to think it is worth the time to try to find the leak with a system 14 years old. Basically replacing the existing evaporator coil is a little less than half the cost of installing a whole new AC system.

mattmia2

making a transition to connect one size furnace to another size coil or furnace or coil to ductwork is done all the time. i wouldn't really consider that an issue.

aspen coils can make/stocks various size coils so you could probably get a coil from them that fits and is compatible with your condenser.

you'd want to separate the coil and the condenser and pressure test them overnight to a couple days with nitrogen to see where it is leaking before replacing just the coil.

your condenser really doesn't get a lot of use in chicago. unless the system was contaminated or it was run without charge for a while rust is more the limiting factor in the life of the system. every time i buy something new i feel like it is worse than what i'm replacing. while you have the system open it would be worth it to add some schraders for low and high pressure switches if it doesn't already have them to protect the compressor if the charge escapes again or the condenser fan or air handler fails.