Hot Water Problems

I have a super-duper high efficiency on-demand hot water heater that is a backup to the solar hot water. After it was hooked up, but before we moved in, sometimes the hot water didn't work at all. It turns out there was some problem with the gas line being too short, so gas pressure didn't build up, so it didn't always work. Or something like that. So Steve Carlyle of O.C. Mechanical added a loop in the gas line to make it longer. Then it worked fine. Then, a couple weeks ago, my morning shower was warm, but not hot. That continued, so I emailed Steve, but he was out of town. I talked to him when he got back and he came over to look at it, but couldn't find anything wrong. Then I figured out the luke-warm showers started about the same time I installed a Waterpik Ecoflow Showerhead. I like Waterpiks and always have had one in every place I've lived. I like being able to hold the showerhead and rinse off more easily.
There were two problems with this Ecoflow, though. Number one, the shower spigot was way up near the ceiling, and when I installed it, I could barely reach it standing on my tiptoes. When I complained to Jeffrey (who is like 6'6" or something) that the plumber was an idiot for doing that, he admitted he had marked the spot for the spigot. Well, I've shrunk to 5'51/2" now, and I'd try to put the showerhead back in the holder, and wouldn't quite make it and twice if fell and banged on the tub, and the third time it fell and hit me on the head. The next day I went to Home Depot and bought and extender. I bought it right before I had a dinner party, and put it somewhere to get it out of sight, and then I lost it. But I found it tonight. Oh, the second thing that was wrong with the Ecoflow was that it said on the package it had a "pause" button. I like that, because, being green, I don't like to waste water. So I like to turn off the water while I wash my hair and lather up. If the water's on, it washes everything off while you're trying to lather up. Anyway, the pause button lowered the flow considerably, but didn't shut it off. Pause means stop temporarily to me. When I read the fine print, it never said it stopped the flow. It tapped danced around what the pause button really did. So when I bought the extender, I also bought a real pause button to hook on it. Then I figured out the third thing that was wrong. It was so "lowflow" that it wasn't triggering the water heater to come on. So I was getting the heat from the storage tanks, which has been about 104 degrees early in the morning, but the water heater wasn't kicking in. That's why the showers were warm, but not hot.
So tonight, I took out the Ecoflow, seen here below (see how close it is to the ceiling!)
and put back the Delta lowflow with an extender and the stop button. I'll get a different Waterpik that's not so lowflow. So I have this beautiful Waterpik Ecoflow I can't use. I'll give it to my sister Cathy; I remember the last time I visited her, she had such a lowflow contraption that it took five minutes just to get wet.

Then another problem with the hot water is that I keep the tank capped at 110 degrees. This is lower than even the LEED certification requires (120). But my mom doesn't want the water really hot because she's afraid she'll burn herself, that's why I keep it at 110. When the storage tanks are hotter than 110, though, the hot water heater won't kick on, it just lets the hot water pick up heat from the storage tanks, which are getting up to 160 degrees now in the afternoon, on a sunny day. They'll get even hotter as the sun gets hotter. So that's a problem. I need to let the tanks get hot so the heat lasts all night, which it has been doing. I'll need to talk to IPS and Steve of O.C. Mechanical to see if there is a fix for that.