Heating Help

Hydronic piping layout

I am remodeling my basement, and want to add a new zone to
my existing hot water baseboard system. 
My question regards piping. There are two door ways that need to be
navigated to complete the loop. In past discussions I have been told that I can
not run pipe over one door header, then back down and over a subsequent door header.  Is this correct?  I do not have an issue cutting the slab and running
the copper through an insulated chase.


Any input would be greatly appreciated.

Hydronic piping in cellar:

What reasons did they give you for it not working?
I'd like to know what I have been doing for years thatworks and doesn't work now and what changed.

Justification for issue

The answer I received was vague and had little to do fluid
flow theory and mechanics.  Insufficient
pump head was not mentioned either. I was told that would add excessive noise.
Nothing relating to hammer, cavitation, just noise.  If this is completely unfounded and you have
had numerous successes running pipe up and over doors, I will gladly do it.

the only reason I could think of

is that they could be air traps if you had air problems.

Good purging and a good quality air separator along with good "pumping away" practice could make that a non-issue.

Pumping Away

Thanks everyone for the input.

What does "pumping away" refer to?.

Pumping away....

means to have the system circulator pumping away from the extrol/diaphragm tank. This arrangement is better because it allows the system to run at a pressure that will keep air more or less in solution and not bubble out into the piping creating air locks and noise. Many systems are pipied w/ the circ on the return side of the boiler effectively pumping  toward the extrol tank.