I'm with you on the cost-benefit thinking. Last year I thought my rusty heater just needed a quick patch-up...big mistake. Ended up replacing it anyway.
Learned that lesson the hard way, haha."once rust starts showing externally, internal corrosion often isn't far behind."
Replacing is usually the safer bet, but honestly, I've seen some heaters with surface rust that still had plenty of life left inside. External rust doesn't always mean internal doom—depends on the location and severity. Had a customer last month whose heater looked rough externally, but after inspection, internals were surprisingly solid. Sometimes a thorough check-up can save you from jumping the gun on replacement...though I get why you'd rather not risk it again, haha.
Had a similar situation a couple years back—heater looked like it'd been through a war on the outside, rust everywhere. I was ready to toss it, but figured I'd pop it open first just to be sure. Glad I did, because inside was surprisingly clean and solid. Ended up sanding down the surface rust, repainting it, and it's still running strong today. Definitely worth checking thoroughly before pulling the trigger on replacement...but yeah, sometimes peace of mind wins out.
Went through something similar last winter. First-time homeowner here, so naturally I was pretty cautious about anything involving gas or water heaters. Mine had rust spots all over the bottom and sides, and honestly, it looked like it was ready to give up any day. I spent a few sleepless nights imagining worst-case scenarios—leaks flooding the basement, gas leaks, you name it.
Anyway, I called a plumber friend to come take a look, figuring he'd tell me to replace it immediately. Instead, he opened it up, checked everything thoroughly, and told me the inside was actually in decent shape. He said surface rust isn't always a sign of internal corrosion or imminent failure. Still, I wasn't totally convinced—peace of mind is a big deal for me, especially with something that could potentially cause serious damage or safety issues.
I ended up sanding down the rust spots and repainting it with some rust-resistant paint, just like you did. But even after that, I kept checking on it obsessively for weeks afterward. Eventually, I decided to install one of those water leak detectors nearby just to ease my anxiety a bit. It's been almost a year now, and it's still running fine...but honestly, I'm still keeping an eye on it.
I guess my point is, sometimes the heater can look worse than it actually is—but if you're anything like me, the peace of mind factor might tip the scales toward replacement anyway. Rust on the outside doesn't always mean disaster inside, but it's definitely worth getting a professional opinion if you're unsure.
Had a similar issue about two years ago. My heater had rust patches, and I was convinced it was on its last legs. After some research, I learned that external rust isn't always a death sentence—it's internal corrosion you really need to worry about. Ended up flushing the tank thoroughly, replacing the anode rod (cheap fix), and repainting the outside. Still going strong today...but yeah, I installed a leak detector too, just in case. Better safe than sorry.
