Primary loop / Secondary loop

[JRG]

I guess I should have done some more research, I did find that this setup is the standard.
The spacing between T's is very important as well as the stubs for primary / secondary systems.
Now this brings up a new question:
I have a very small system, 2 zones basement and main floor.
Approx. 800square ft per floor.
Very little piping as you can see.
Could I get away with just a primary zone?
I have approx. 10deg F drop in temp from my supply to return.
I am going with a boiler instead of the tank less hot water supplying a heating box for my radiant heat.
The heating box has broken down and I don't want to put money into it.


I have this setup and don't understand the cross section between the supply and return.
See attached.
I would think that the supply and return would be separated.

[walker]

Im no expert in these, but I think its acts as a poor mans low loss header.

I'm sure someone with more knowledge on these will chime in.

[Admin]

It does help reduce the pressure drop.

They call this primary/secondary pumping.  This common pipe separates the primary and secondary loops.  The common pipe comes into play when the secondary loop pump is off.  This helps increase the water temperature returning to the boiler.