Morning All, So I am relatively new to the home. It has a hot water heating system I am not that familiar with. I am familiar with a typical boiler, baseboard steam heat, and hot water heater tank. I have a few pictures that show the entire system. My question is, where and how is the hot water heated and what would cause hot water flow to drop to the point where sinks and showers have good cold pressure but struggle to output hot water? I know there is the black knob shown in the attached picture which allows me to regulate how hot the water throughout the house gets. I can turn it from 120 to 160 degrees. It will make it hotter (a little) but kills the flow. Is it sediment somewhere? Could it be the pump tank? (second photo of blue tank) There is a whole house water filter (just changed filter media) as you can see in the bottom right corner of the first pic. Any advice is greatly appreciated!! Thanks in advance from a noob!