I switched to tankless about two years ago, and while I definitely noticed some improvements, it's not necessarily the magic bullet you're hoping for. Before upgrading, we had the same annoying issue—someone flushes or runs water elsewhere in the house, and BAM, instant ice bath. After installing the tankless heater, things did get better overall. Showers are more consistent temperature-wise, especially if you're just running one at a time.
But—and here's the skeptical eco-friendly homeowner in me talking—tankless isn't always perfect when multiple fixtures are running simultaneously. It depends heavily on your home's plumbing setup and water pressure. In older homes (mine's from the late 1960s), pipes are often narrower or partially corroded, which restricts water flow. Even with a new heater, if someone flushes a toilet or starts laundry mid-shower, you might still notice a slight temp dip or fluctuation—not as drastic as before, but still noticeable.
That said, I don't regret going tankless at all. The energy savings alone make it worthwhile from an environmental standpoint, and I love not having to worry about running out of hot water during longer showers or when we have guests staying over. Plus, it freed up some valuable space in my basement where the old bulky tank used to be.
If your main goal is smoothing out shower temps during simultaneous use though, I'd suggest looking into your home's plumbing first—maybe adding thermostatic mixing valves or pressure-balancing shower valves could help more directly address your problem without such a hefty investment upfront. Tankless is great for efficiency and convenience, but it's not always the cure-all for older-home plumbing quirks...
"maybe adding thermostatic mixing valves or pressure-balancing shower valves could help more directly address your problem"
Good point, but honestly, thermostatic valves made a bigger difference for me than switching to tankless. Installed them last year—no more icy shocks, even with our ancient pipes. Worth considering before bigger upgrades.
"thermostatic valves made a bigger difference for me than switching to tankless"
Interesting perspective, but I had a slightly different experience. When we moved into our older home, we initially tried thermostatic valves hoping they'd solve the cold-shock issue. They did help somewhat, but honestly, the improvement wasn't as dramatic as we'd hoped. Eventually, we upgraded our main plumbing lines—turns out the old galvanized pipes were severely restricting flow and causing pressure drops whenever someone flushed or ran water elsewhere. After replacing them with copper lines, the difference was night and day. No more sudden temperature swings at all.
Not saying thermostatic valves aren't helpful—they definitely improved comfort—but sometimes the underlying plumbing issues are the real culprit. Might be worth checking your pipes' condition before investing in valve upgrades or tankless systems...just something to consider from my own trial-and-error experience.
Good points about the pipes. Another thing worth checking is your pressure balancing valve in the shower faucet itself. Had a similar issue a while back—every flush meant instant ice bath. Thermostatic valves didn't do much for me either. Turned out the shower valve cartridge was old and worn out. Swapped it for a new pressure-balanced cartridge, and problem solved. Cheaper fix than redoing pipes or going tankless, too...might save someone else the headache.
That's a solid suggestion about the cartridge—I’ve seen that happen more than once. But before swapping parts, I'd recommend checking if the shower faucet itself is actually pressure-balanced. Older homes sometimes have standard valves without pressure balancing, so replacing the cartridge alone might not do the trick. Had a client once who replaced cartridges twice before realizing the valve body itself was outdated...talk about frustration. Always worth double-checking the model first to save yourself some unnecessary hassle.
