Sometimes it’s not even the system—just more hot water use than you realize, especially with guests or laundry days.
That’s definitely true, but I keep wondering about the mixing valve settings. Has anyone checked if the tempering/mixing valve is set too low? I’ve seen it a couple times where folks crank it down for safety and then wonder why the showers run cold super fast. Also, what’s the collector orientation like—any shade hitting the panels during peak sun? Sometimes a tree branch is all it takes to knock down performance.
Has anyone checked if the tempering/mixing valve is set too low? I’ve seen it a couple times where folks crank it down for safety and then wonder why the showers run cold super fast.
Yeah, I ran into that exact issue last winter. Thought my system was underperforming, but the mixing valve was set way lower than I realized. Bumped it up a notch and suddenly had enough hot water for two showers instead of one. Also, don’t underestimate how much shade can mess things up—even a neighbor’s fence started blocking my panels in the afternoon and I didn’t notice for weeks. Sometimes it’s the little stuff that makes the biggest difference.
Had a tenant crank the mixing valve way down once because they were worried about scalding their kid. Next thing I know, I’m getting calls about “no hot water.” Took me a while to figure it out. Honestly, people overlook the basics all the time. Shade’s another sneaky one—trees grow faster than you think and suddenly half your panel’s useless.
Shade’s another sneaky one—trees grow faster than you think and suddenly half your panel’s useless.
That’s a good point about shade. I had a similar issue last year—neighbor’s maple went from “nice bit of privacy” to “why is my solar output tanking?” in what felt like a single summer. It’s wild how fast things can change.
On the mixing valve thing, you’re not alone. I’ve seen folks crank it way down thinking they’re playing it safe, but then the water’s barely lukewarm. It’s easy to miss if you’re troubleshooting, especially if you’re expecting a bigger problem.
If you’re still chasing more hot water, maybe double-check the basics: mixing valve setting, any new shade, and even sediment buildup in the tank (that one caught me off guard once). Sometimes it’s just a combo of little things stacking up. Don’t beat yourself up—these systems are finicky, and even the “simple” stuff can trip you up.
Funny you mention sediment—had a plumber out last fall who found a layer of gunk at the bottom of my tank that was basically acting like an insulator. I’d been blaming everything else, but flushing it out made a bigger difference than I expected. It’s easy to forget how much that stuff can build up, especially if your water’s even a little hard.
If you’re still chasing more hot water, maybe double-check the basics: mixing valve setting, any new shade, and even sediment buildup in the tank (that one caught me off guard once).
I’m with you on the mixing valve being sneaky. I always worry about scalding, so I tend to keep mine on the lower side, but then showers get lukewarm fast. Have you tried using a thermometer at the tap to see what temp you’re actually getting? Sometimes the dial isn’t super accurate. I’ve read that 120°F is the sweet spot for safety and comfort, but I’m always second-guessing if it’s too low.
On the shade issue—did you end up trimming back that maple or just live with less output? I’m always nervous about asking neighbors to cut back trees, but it really does make a difference. I’ve started checking my panels every few months just to see if anything’s changed. It’s surprising how fast things grow when you’re not paying attention.
One thing I haven’t seen mentioned much is pipe insulation. If your hot water lines run through a cold crawlspace or attic, you could be losing heat before it ever gets to the tap. Worth checking if you haven’t already.
Just curious—how old is your system? Sometimes those older tanks just don’t hold heat as well anymore, even if everything else seems fine. Not saying you need to replace it, but it might be part of the puzzle.
These systems are great when they work right, but there’s always something new to keep an eye on...
