If you could, please identify the items in the attached pics.
What are they, and what do I do with them?
No problem if they need to be seen in context of where they are installed in the system, let me know.
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Items 1, 2, and 4 are flow control valves. They don't shut off tight like a ball valve, but they add internal restriction to balance flows between various loops that hav different restrictions. And they do it without the noise associated with turbulence. Ball valves, for instance, are terrible for system balancing because they add so much turbulence and noise. You can add restriction to a free flowing loop, to make the higher restriction loop perform and get heat. This what balancing a system is all about.
The fill-Trol valve on the expansion tank is an interesting piece. It is used only with open expansion tanks. An open tank has air exposed to the water, to provide expansion room for the water in the system, when it heats up. It is a tank with both water and air in it. When the water heats up and expands into the tank, it absorbs air. Then that air is carried around and delivered to bare iron parts that can rust. Air can also accumulate and cause problems with noise and circulation. Eventually, closed loop systems can fill completely with water and have no air cushion. This leads to wild pressure swings, corrosion, leaking, and a general deterioration of the system. The fill-trol stops this form happening with a dip tube that reaches up into the water and somehow prevents air absorption. Modern systems with diaphragm tanks do not use these, because the air is separated from the water with a rubber membrane.
To me, the old school open tanks are superior. One of the most common system problems with modern hydronics is the diaphragm expansion tank.
I designed the system at my house with an open tank. However, I located it up high and on a dead end line. No hot water reaches the tank to absorb more air. It cannot accumulate an air bubble anywhere. And the absorbed air, actually, oxygen, in the water cannot cause corrosion, even if it does find some iron, because I have a corrosion inhibitor that keeps the system fresh and free flowing.
