I bought the brand often called the most reliable (Trane), and I bought a nearly top unit with 10 year warranty (I avoided the most expensive unit because it was twice as complex and had other issues, notably R22, that made me wonder about the long term). I had it installed by an installer recommended by an engineer friend. It's been maintained every 6 months by a top rated servicer. And yet, it looks like I may have to replace my central air conditioning system after only 12 years of service. It failed for the first time in years in June. I called out the servicer and they fixed it with a Freon recharge and EZ seal. There appeared to be a significant leak, probably in the indoor coil which would cost $1000-$3000 to replace. They predicted 18 months to 2 years more service if the EZ seal worked--at which time I'd have to replace the entire unit. The only previous failure I've had was when the compressor went out in 2008, just after 5 years of use. Fortunately that was covered by the 10 year warranty I had, under which I didn't pay anything (I think you need extra contracts to cover labor now, and maybe I had done that in 2003).
I was thinking air conditioning (I mean heat pump) systems, the good ones, should last 20 years. And I was thinking I was doing more than most people, so I should get at least 20 years. Now my servicer tells me that 10-15 years is the norm in San Antonio Texas, and that I've done well keeping it to at least 12. (Of course they would say that, being that they've done all the servicing.)
I don't feel good about this, and I wonder if it isn't a kind of scam. An air conditioner is just sitting there, doing a job it is engineered to do. I don't see why it couldn't last forever with only small part changes. It's a very different situation from, say, an automobile, which faces road hazards, driver hazards, and so on, and yet they're typically doing fine in 10 years now, and still running at 15. That to me sounds like a much harder job.
One problem is that after 10 years or much less, your replacement options are limited. You may not be able to get a new outdoor and/or indoor unit unless you get a whole new system.
Another "problem" is that the technology does actually keep improving. They often say that after awhile you are better off getting a new unit because of energy savings, you might come out ahead (in actual money) in just a few years. I suspect that's rarely true now if it ever was, because most units have been replaced since at least 10 if not 12 SEER was the norm. The change from 5 to 10 SEER was far bigger a cost difference than 10 SEER to 20 SEER. Consider the following napkin example:
5 SEER energy cost $4000/yr
10 SEER energy cost $2000/yr.
20 SEER energy cost $1000/yr
Now 5 to 10 and 10 to 20 are both doublings in efficiency, and energy cost is also halved each time. But the first halving made a $2000 difference in annual cost, whereas the second halving only made a $1000 difference. That is half as much savings from the second doubling in efficiency. For me, since I'm already at 15 SEER, a 20 or 21 SEER replacement won't be that much of a cost reducer.
My own experience with a higher efficiency heat pump (supposedly 15 SEER as compared with the original 5000 or less) was that I saved nothing in energy costs. Instead, I ran the system for full comfort, not fearing it would fail from running all the time. Full comfort for me meant cooling to 75-80 and heating to 72-75. Now this kind of factor is so commonplace economists have a name for it, how often "savings" from efficiency may lead to greater expenses. But I'm thinking in this case, it wouldn't happen a second time, because I'm already extracting full comfort or nearly so. And new systems extract humidity more efficiently (without as much extra running) compared with mine. Still, based on my last experience of saving nothing on energy costs, I have doubts.
And that $1000 difference is about the same as the $10,000 replacement over 10 year use, by which time it's almost worn out and time to buy yet another. If you include interest and maintenance costs, the total amortized equipment and service costs are likely greater than the energy costs nowadays. And it seems hardly anyone is talking about things that way…instead I'm still hearing about how efficiency pays for replacements.
The thruway culture aspect bothers me, along with the high cost of buying and servicing central and also "ductless mini split" air conditioning systems. A friend of mine and others have switched to using room air conditioners because they are so much less expensive to buy, can be user installed and don't require professional periodic maintenance. In fact my friend was distressed by the idea that I wanted to stick with the exorbitantly costly central air conditioning model when room AC is a less expensive overall system…allowing for and assuming a some loss in comfort as well (you're not trying to keep the whole house comfortable 24/7 like me). But both she and her mother now get by with room air conditioners in their houses, and it's ok, and she remembers back before the room air conditioners… And all we need here in central texas is radiant electric heaters for local and temporary heat which doesn't cost much. I like the fluid filled radiator style, which I used in San Francisco but not anymore here--since my room remodeling my master bedroom doesn't need supplemental heat, I sleep with a sheet or less year round, and nowadays blankets cause cramps, and I maintain a comfortable house getting more comfortable mostly, I hope.
Given how expensive it is central air conditioning and heat pump systems should last much longer when properly maintained. Given that I have little assurance than any system is going to last much longer, it also seems that it's not worth spending that much more for a super efficient system, which is just going to have to be replaced in 12 years like any other. I've heard claims that ground sourced heat pumps last longer but I'm doubting it, and wondering how much higher the maintenance costs are, not to mention the much higher initial cost.
