This is the kind of engineered obsolescence, designed-to-fail stuff that just infuriates me.
Our home A/C is a Trane XB10 from 2005, about 3 tons IIRC. It just died. Technician found the leak with his sniffer at the evaporator, which is a tube-and-fin style. IT has copper tubes with aluminum fins, pretty typical. At the end of each tube there are u-bends of copper brazed/soldered on to plumb all the tubes together. Also quite typical.
Ah, but the header plate at the end? GALVANIZED STEEL. Now, you might already know that zinc touching copper is going to cause galvanic corrosion of the copper. There's no way the engineers at Trane did NOT know this.
But who cares? That means when the evaporator fails in 15 years because of corrosion they could have prevented, you won't be able to get a replacement part (naturally, out with the old) so they'll get to sell you and entirely new system for $10,000+ because they decided to use cheaper galvanized steel instead of aluminum for the header plates.
So now the question becomes: Now what? What do I get to replace this rusty old dumpster fire of an HVAC system that has never worked very well in 20 years?
Since the furnace also needs to go (it's very rusty), I'm thinking just biting the bullet for a whole new system. The ducting in the house seems fine. But I'm pretty frustrated that my 2005 HVAC system is essentially no different from a 1960s unit-- single speed fan, single speed compressor, constant output furnace.
Best I can tell, I the smart call for my part of Indiana is a higher capacity heat pump with variable speeds on the compressor and fan and then have the gas furnace backup for when the heat pump cant keep up.
Sometimes being an engineer means living a life of frustration when you can see every defect of design right in plain sight. Especially when it costs you a small fortune.
