Mixing valves... the sneaky troublemakers of plumbing. Had a job last month where the homeowner was convinced their solar heater was just “old and tired.” Turned out, the mixing valve was basically bottlenecking all that nice hot water, like a traffic jam but for your shower. Swapped it for one that could handle the higher temps, and suddenly it felt like a spa in there.
Funny thing is, I used to think bigger pipes and tanks were always the answer, but sometimes it’s just that one little valve causing chaos. I do wonder if folks check the temp settings too—seen a few set way low because people are scared of scalding, but then you barely get a warm trickle. Solar setups especially seem picky about the right mix.
Anyway, wild how you can go from ice-cold misery to actual hot showers just by swapping out a part that costs less than dinner out.
Getting More Hot Water From My Solar Heater—What Am I Missing?
“Swapped it for one that could handle the higher temps, and suddenly it felt like a spa in there.”
That’s interesting about the mixing valve. I’ve always assumed if the water was lukewarm, it was either an undersized tank or just not enough sun that week. Never really thought about a single valve making that much difference.
I’m curious—when you swapped out the valve, did you have to mess with any of the anti-scald settings? I’ve read those can be set pretty conservative from the factory, which is safe but not exactly great if you want a hot shower. I’m all for safety, but if I’m paying for solar, I want to actually feel some heat...
Also, does anyone know if certain brands of mixing valves are better for solar setups? Or is it just about making sure it’s rated for higher temps? I’m trying to avoid spending more than I have to, but don’t want to cheap out and end up with the same problem again.
Mixing valves are sneaky little culprits—seen a lot of folks blame the tank or the sun, but it’s often that valve throttling things down. When I swapped one for a solar-rated model, I did have to tweak the anti-scald setting. Factory defaults are usually set for “lukewarm at best,” which is safe but not exactly spa-like. Just don’t crank it too far or you’ll be doing the hot-foot dance.
As for brands, I’ve had decent luck with Watts and Honeywell—main thing is making sure it’s rated for higher temps (some go up to 180°F). Cheap ones tend to stick or get weird with fluctuating temps, so I’d avoid bargain-bin specials if you want consistent hot showers.
Not sure I’d pin it all on the mixing valve, honestly. They can be a pain, but in my experience, solar heaters sometimes just don’t recover fast enough if you’re pulling a lot of hot water back-to-back. Even with a good valve, if your collector or storage tank isn’t sized right for your usage, you’ll still end up with lukewarm showers.
Cheap ones tend to stick or get weird with fluctuating temps, so I’d avoid bargain-bin specials if you want consistent hot showers.
That’s true, but I’ve also seen some higher-end valves act up if there’s mineral buildup—especially in hard water areas. Sometimes folks swap out the valve and still have issues because the lines are gunked up or the check valves are sticking. Worth checking the whole system before dropping cash on a new part.
If you’ve got a recirc loop or booster, those can mask valve problems too. Just saying, it’s not always the valve’s fault.
I’ve run into the same thing with my setup—thought it was the valve at first, but after flushing the lines and cleaning out some scale, things improved a lot. Hard water’s a real pain for these systems. I do wonder, though, how big is your storage tank? I found out the hard way that mine was undersized for our family, especially in winter when the sun’s not as strong. Ended up adding a small electric booster just to get us through cloudy stretches.
Have you checked if your collector is getting enough sun throughout the day? Sometimes shade from trees or even a neighbor’s new fence can sneak up on you and cut down the efficiency. Just curious if you’ve noticed any changes there, or if it’s always been like this.
