There is a problem with the piping design for the wood boiler. I finally got all the leaks fixed and the system holds air pressure, but I had the vent pipe plugged so that air would not escape up into the overflow/header tank.
Sometime in the process I started to wonder what was going to keep the water from just pumping up into the header tank and filling it to overflow instead of pumping the water out to the storage tank. The pump puts the header tank under pressure from below. The pipe is plumbed to dump the water into the tank but through an open hole, not a sealed one. This open tank just doesn’t seem to make sense.
In fact the water enters the tank from an opening in the side, more like this drawing.
I planned to plug up the other opening in the tank and connect a tube to the highest as an overflow. I didn’t have a return loop to the boiler from this tank because I am filling the system from the storage tank side where the incoming water is located.
The overflow is supposed to go into the upper tank if the stove gets too hot–here is the photo of it getting temporarily installed for testing.
The pex pipe would connect to the upper copper pipe and the air assembly below that disassembled and plugged since I won’t have a cold return from the tank. Unless I have to! More investigation is required. I did post this question at the Boiler Room at Hearth.com hoping some expert will let me know how to deal with this issue. (Hearth.com experts were not happy with the pex pipe to the overflow, nor the small size of it–and cautioned that the pex would expand and move with any heated water in it and possibly disconnect from the tank entirely, so this pipe would have to be copper too–I had planned to use copper when the tank was moved to a structure above the stove but now the entire open system is scrapped for a closed system instead–See Wood Stove Clarification.)