Ever check if your anti-scald setting is too low? Sometimes those get bumped during repairs or cleaning and limit the hot water. Also, are you sure your mixing valve is rated for solar setups? Some aren’t built for the higher temps.
Also, are you sure your mixing valve is rated for solar setups? Some aren’t built for the higher temps.
That bit about the anti-scald setting getting bumped is spot on. I ran into that at a job last month—customer swore their water heater was “broken” after a plumber swapped out a cartridge. Turned out the anti-scald dial got nudged way down during the install. Easy fix, but it’s not always obvious if you don’t know to look for it.
About the mixing valve, I’ve seen some that just can’t handle the higher temps from solar setups, like you mentioned. Some of the cheaper ones start sticking or leaking when the water gets hotter than what they’re rated for. Did you notice any weird noises or sudden drops in temp at the tap? Sometimes that’s a clue the valve’s not happy.
One thing I’m curious about—do you have a recirc line or is it just a straight run from the tank? Sometimes long pipe runs cool things off before the hot water even gets to you, especially if the pipes aren’t insulated. Just a thought.
I get what you’re saying about the mixing valve, but honestly, I don’t see as many issues with them as folks make out—at least not if you go with a decent brand. Sure, the cheaper ones can stick or leak, but I’ve seen plenty of solar setups running just fine for years with a solid valve. Sometimes I think people swap them out too quick when the real culprit is something else.
Sometimes long pipe runs cool things off before the hot water even gets to you, especially if the pipes aren’t insulated.
That’s a big one in my experience. I’ve lost count of how many “hot water problems” were just cold pipes sucking up all the heat before it ever hit the tap. Even with a recirc line, if your insulation isn’t up to snuff, you’re losing a lot more heat than you think. I’d check your pipe runs and insulation before blaming the valve. Honestly, half the time it’s just heat loss along the way, not the gear itself.
I hear you on insulation making a big difference, but I’ve actually seen mixing valves cause more headaches than folks realize—especially when they’re not sized right for the flow rate. Even with good brands, if the valve’s undersized or not set up for solar temps, you can get lukewarm water or weird fluctuations. Had a job last month where the valve was technically “fine,” but just couldn’t keep up with the demand. Swapped it for a higher-capacity model and the problem vanished. Sometimes it’s not just the cheap ones that act up...
I ran into something similar—thought my solar heater just wasn’t cutting it, but it turned out the mixing valve was the real culprit.
That’s exactly what happened here. Swapped for a bigger one and suddenly showers weren’t freezing halfway through. It’s wild how much that one part can mess with the whole system.“if the valve’s undersized or not set up for solar temps, you can get lukewarm water or weird fluctuations.”
