Geothermal units work well and save a lot of energy in the production of warm and cold air. What we are talking about, here, is how that air is distributed throughout the home.
Folks, you may want to review NEC 300.22 especially section ©
Wiring within air handling spaces in dwelling units.
Now you’re just clouding the issue 
It is what it is Jeff 
The way I read it NM is not one of the permitted wiring types in the space in question.
It is not a constructed plenum/duct so section (C) applies.
I would have to agree.
Let me pee in your post Toasties some more, supply air is not allowed in a wood chase period it does not matter what the source of the air is. Return air is allowed in a wood chase and again supply air is not allowed. Ya guys were just discussing the heat side think about what the moist air will do to those wood chases in the cooling mode Geez come on guys
*Furnace blows warm air into the Floor cavity, and then subsequently out of the registers. Cold air return is natural though the louvered doors, stairwell, and balcony. This is an irregular but not necessarily an unsafe method of heat distribution considering the heat is geo-thermal. Installing ductwork would help improve the efficiency of the air flow system, but would change the “warm floor” feeling. *
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Gee is this much different then what My gas fire place does blows warm air out into my rec room??? Roy
Roy, it’s wrong.
What does Canadian code say?
First reply… Roy
No.
I don’t know how the tubing which is well below frost line would burst due to freezing.
Also the water in the tubing is mixed with glycol so that the water doesn’t freeze. Tubing is guaranteed for 50 years.
That floor space is adding allot of extra volume to the system that it may not have been designed for. Also how is space not being heated? The space below is being heated just as much as the space above. I also wonder how well sealed the whole things is to direct the air to where it needs to go, a duct blaster test would be very interesting to see if and how much leakage to the outside there is.
If you did not call this out and I was the buyer you and me would be in court and I would be asking you to pay for proper duct work and to re- mediate the mold that was growing in the the supply air duct during the cooling mode:shock::shock:
Better yet why don’t ya send me the name and E-mail address of your buyer and let me talk with him perhaps me and your buyer can split the settlement
I had a 10000sf house in 2007 that had geothermal that used the whole underfloor area as the supply plenum for the first floor. It was a poured concrete crawlspace that was sealed and completely lined with a sealed membrane, like a shower pan. Of course this was an integral part of the design of the house and not an afterthought.
It was the prettiest house I think I have ever inspected.
That is still not wood, wood supports mold growth
Like Charlie said:
Call it or send them my address for the future suit.
For Example:
There was NO ducting present. Furnace blows warm air into the Floor cavity, and then subsequently out of the registers. Cold air return is natural though the louvered doors, stairwell, and balcony. In our opinion this time of arrangement would tend to be inefficient and has potential for air leakage, hig utility bills and mold growth. In 35 years we have never seen a system like this. In our opinion there [FONT=Arial]were [FONT=Verdana]conditions present in the [/FONT][/FONT]heating system that indicate a liberal approach to normal and proper installation practices. WE believe this type of installation has potential to become problematic in the future. We recommend having a licensed and competent HVAC contractor read the inspection report; evaluate the buildings heating and mechanical system; then service, repair, modify or replace any unhealthy or unreliable conditions or deficiency’s in a safe and proper manner prior to closing.
Was the Builder Korean?
Ondol
Would be State of the art Heating in the Bronze Age.
This design was/is used in some commercial/industrial applications where the plenum space is absolutely sealed and CFM/FPM design is part of the Med. or High velocity design. I’ve never seen what you are describing in a residential setting, and would be very suspect, not only for heating capabilities but especially for cooling purposes. I’d also be worried about the possibility of mold becoming a problem within the supply plenum space. IMHO
But in those cases you cannot use type NM wiring.
From my training…
Open framing only acceptable for means of return…
never supply…
Note and recommend further review / repair…
That is irrelevant its secondary to the primary problem install proper supply air distribution duct and your NM wiring will be just fine;-)
It is not irrelevant by any means. Read the NEC.
This wiring method is simply not permitted in environmental air passages.
If the wiring was in pipe or using approved materials you could have this type of plenum.
Is it a great idea? no.
Would I call it out? yes
Whenever I see something out of the ordinary I call it out and express my concerns apart from any code.