You are correct that many HVAC guys don't know much about sub cool and TXV's. Pistons are still used and many conventional systems are charged by super heat.
Geo units have been exclusively TXV from the giddyup, so most geo mechanics are going to understand TXV's, sub cool etc. For those who don't know how to do the math, digital gauges do it all now.

Posted By joe.ami on 09 Oct 2013 08:35 AM
"I do again understand the difference in heat rejection"

Okay so since you are an ME perhaps you can explain to me the difference between cooling and rejecting heat (cause that's generally how we cool in unsophisticated HVAC land).

They certainly are not one in the same but target the same goals and work hand in hand.  One is resistance of thermal gain, the other is transfer of the thermal gain (btus).  There has been quite the misuse of terminology in "heat rejection" and heat ejection".  Some refer to them as one in the same but they are not, or at least how I was taught. 


Anywho, maybe we could get down to productive chat?  Is there any geo data I can obtain through the geological sites online to determine approx soil temps at depth in my area? 

As well, I am trying to make some decisions regarding O2 barrier tubing for the radiant floor.  I will probably just use barrier tube for the floor regardless but due to cycling fluid into a geo loop, the entire geo loop would need barrier pipe unless I use a water/water exchanger which I kind of planned to do anyway. 

The general thoughts on O2 as I understand it are mitigating the corrosive properties of O2 in water.  However, I seem to remember O2 filtration components that might function as the same? 

I still have not done enough research to determine what type of water I want in the system too.  As of now it seems that distilled or very pure water may be a no-no and possibly just using some decent demineralized water that would still have enough mineral base to be non-reactive? 

We generally use what ever water is on hand. Some suggest distilled, some suggest that distilled is a vacuum that will attract contaminants. If you are recirculating water in a closed system with no loss, then you shouldn't concentrate junk like you would in a boiler system for instance.

You could look at the geo designer software from Climatemaster for approximate soil temps at depth, but as you mentioned before, they will not remain unaffected by your loop system.

There are experts in various radiant floor materials in the radiant forums.