PEX pattern for pasv solar gain redistribution?
 

Within a 16x16 4" slab that has the front half in direct passive solar exposure is there a best pex layout pattern for both standard hydronic heating and distribution of solar gain by running pump more or continuous? I can think of concentric outer to center layout, back and forth from front to back and side to side front to back. Any modeling or work in this that anyone has come across.

The adjacent 16x16 loop of 16x32 floor does not have more than 25% solar exposure so the potential or need to redistribute solar gain is limited.

That is an easy one. Your hot line which would be leaving your boiler should go to the coldest area which is the window. So, under high solar gain, that heat is moved to the cooler area on the way back to the boiler(regardless of whether it is on or off) and during night time, the boiler may be running and doing its normal thing.

Yes, that makes sense but what pattern might best accomplish this. Circular exterior to interior and back out, linear back and forth across floor area from front to back(at desired spacing) or linear back and forth, side to side from front(solar gain area) to back(cooler non exposure area)? Or might they all work almost equal. My thinking would be the from front(as you say window loss area) to back(area of continuous insulation, no windows) might be best. Fluid would hav greatest amour of time to pick up solar gain and have greatest contact with cooler floor area. Sound reasonable?

When I do this (which is often as I do lots of passive solar houses) i run straight to the old wall (window) and serpentine back. I use the concentric circle design when I am doing a larger room with a consistent, average heat loss throughout the room.

Mike, Old wall??, is this a typo for cold wall? Wall of greatest heat loss? Which in passive design is likely the south window wall. You pattern your pex run serpentine back thru passive gain area(E/W) into non passive area of floor than back to manifold. The adjacent half of full floor is as you suggest more heat loss/gain uniform and I plan the spiral out to in pattern. Is there a significant head or flow pressure difference in layout patterns that has to be balanced? I.E, can one loop be serpentine another circular and still be in same zone if matching length?

Opps, missed a C there. No problems doing the circuit either way and there should be no difference in pump head, just takes longer to put the tubing down when you have more bends.