Haven't seen many issues, so far, with Trane but Carrier version we have a near 100% failure rate within the 3 year warranty period. Mostly on Gemini. I do have an Aquasnap in its 3rd year with no leaks so far. 14 coils, I think, on it. Does have an intermittent HP issue on Circut C but the coils seem to be holding up on it. Compared to the GX it replaced cleaning is almost a pleasure.
Here's a very good cut away photo of micro-channel condenser.
This design has been used in car A/C condenser for a long time.
I don't know the advantage to having dividing bridges and have multiple channels as opposed to one flat shaped tubing. Perhaps it adds structural strength to resist ballooning under pressure.
Flat surface provides much more effective surface are for fins to attach onto. The fins on automotive A/C coil is fairly rigid while tube and fin HVAC fins are paper thin and very finely spaced such that it traps cottonwood, lint etc like a filter media.
It is resistant to galvanic corrosion as long as it is properly isolated from contact with anything conductive. Think about it. Car condenser is exposed to road salt splash, road debris and severe vibration. The aluminum parts are galvanically isolated from steel with rubber grommets and plastic stand-offs.
Car A/C is about 1.5 tons and the evaporator is the size of a letter size paper and condenser is about the size of a 26" TV screen due to space limitations.
This translates to condenser running at 30-40 F above ambient which means even though 134a is a medium pressure refr, it runs at 410A like pressures. When its 105F, condenser runs about 340psi. Despite this, car condensers usually don't leak unless a big debris hits it or you crash the car.
Stationary AC units aren't exposed to the same level of corrosive salts or vibration.
What I read is that well made elastomer seals with o-rings resists leaks better than flare fittings in less than ideal environments. So, the condenser can be fitted with automotive like bolts and o-ring and the copper line can be brazed to that fitting piece. The copper/aluminum junction can be tarred to protect from elements and if there is a galvanic corrosion it will be that fitting that needs replacement. Not the condenser.
For refrigeration applications you could use two coils and use a three way valve to choose summer only(all coils) and all year configuration (partial coil used) with minimal effect on total system charge.
Caustic and acidic chemicals will damage aluminum, but conductive(ionic) chemicals are fine as long as its not in direct contact with other metals.
Copper free construction gives modest edge against metal thieves as long as scrap aluminum value stays low enough to not attract scum bags. Obviously it would have to be marked "copper free coil" clearly.
The new micro channel coils have even smaller passages than that automotive one.. There is a cuttaway of a york one at one of my wholesalers, and the passages are probably a quarter the size of the one in that picture. Just askin for problems if u ask me..
It depends on your monitor and all that, but on my screen, it definitely comes up about 4-5 times the size of the actual coil. The tube (containing multiple channels) is only 1/2 to 3/4" wide.
Originally Posted by coolerik
As someone else already said, don't get trash in there.