hydronic heat for the barn - part 3

My much anticipated online order of hydronic plumbing parts finally arrive after a week from the East Coast. I had no disillusion that despite my well laid plan and countless check and reviews that it will need a few iterations to get all the parts procured. Having the physical parts is necessary to lay them out and check for accuracy and fits against my schematic. While I can lay out the parts on a mockup set on the floor it is only 2D. The actual plumbing installation is a 3D real world.
 I planned this being the first of two orders I will need to get all the needed plumbing parts. I am thankful it arrived on a Friday to give me plenty of time to get as far as I can and identify the remaining parts before Monday rolls around.

The boiler combustion air ports are 3 inch but because I have such short run even with 2 inch pipe I will have next to no restriction to worry about. I figure out using two 3"-2" bushings is the lowest cost design as I only need to buy one 2" pipe, 3 ells, and a couple of couplers. I will use the coupler to create DIY screen fitting to prevent critters from getting into the pipe.

the down adapter bushings is the most elegant solution

the 1 1/4" x 1 1/4" purge tee valve is the only thing that tripped me up in my schematic that I used to identify the needed copper and brass parts; it is longer than I expect WRT to the two water ports of the boiler

as I said it is a 3D problem so the radius of the expansion tank must be comprehended in the plumbing installation

these isolation valves have integral drain port as well as union which make removing the boiler a snap

next I locate the left most side of the manifolds

all these copper plumbing parts I have will save me a lot of money

I use this piece of cardboard to accurately lay out the plumbing parts in 2D

there are a few alternatives and I want to optimize their placements, particularly the expansion tank so it is least likely to be bumped into

checking the instruction it seems that putting it upside down is not advisable

because of the  1 1/4" x 1 1/4" purge tee valve length I overlooked I am short two 1 1/4" ells

my intuition is to run the outgoing hot water through the manifold that has the flow valves thinking the clear plastic flow gauge would be better protect if they are on the return path

checking the instruction it shows the flow gauges should be on the out going hot side

Thinking about how these flow gauge work I know I cannot have the flow in opposite direction as they simply will not work.

so the manifold with the flow gauges will need to be on the bottom where the hot water supplied by the boiler and fans out to the 8 loops

so with the 2D mockup I identified that I need to procure two 1 1/4" ells but when it comes to plumbing you can never be 100% certain until you are done

While I have yet to have everything I need to complete the installation. What I have on hand are enough to keep me busy over the weekend, and able to identify the remaining parts, which include a circulation pump. As to the right pump there are more pumps out there than you can shake a stick at. That is the problem with Western democracy when there are too many choices. I like Taco as they design their pumps with replaceable motor cartridge. I never had one that failed on me. 

My goal is to not having to drive anywhere on a special trip or pay shipping to get what I need. So far I have been successful.