Anyone built or seen a trombe wall built into an ICF wall?

I have two corner fireplaces going into my new ICF home, one in my basement, and one in my main floor living room.  These will be efficient zero clearance wood burning stoves/fireplaces totally inside the ICF envelope.  These are being installed one above the other with both flues sharing the same chimney chase.  These fireplaces will occupy a triangular space of approximately 6' x 6' x 8.5'.  These fireplaces are on the back of the house which faces due south.

On the exterior wall over these corner fireplace "rooms", I'm thinking about incorporating some passive solar heating in the form of trombe walls thus:

Strip off the outside layer of ICF foam to accomodate a 4' wide x 6' tall double pane (fixed) window (not low-e).  Paint concrete flat black.  Install window in foam cut-out using tapcons into the concrete.  I may have to fur out the window a bit if the 2.5" of removed foam is not enough clearance for the window frame.  Flash as you would any other window.  Prior to the pour I would install some 4" or 6" pipe chases in the concrete wall at the bottom and top of the window opening to allow the heated air to flow up and into the house.  I may install some small fans to help circulate the warm air.

On the exterior I would buy or build some operable insulated shutters.  Close them in the summer, open them in the winter.

I'm located in central Arkansas.

Good idea or waste of time and money?

Interesting. If I were you I would cut out the "window" before the pour and block it out to the depth you desire. This way you'll get exactly the depth you want. ICFs have ridges or dovetails to grab the concrete and by design are very difficult to remove from the foam. Some ICFs don't have this "feature". This feature is desireable because concrete shrinks about 1/100th of an inch per inch of thickness. When the concrete cures it will pull the wall in and basically lock it to the foam. This is a tornado feature - but is really there to ensure that if water ever got into your wall due to a roof leak it would be forced to move more or less straight down.

I'm using LiteForm Xtra ICF with are smooth on the back. They still stick to the concrete, but are easier to pull away than the forms with grooves on the back.

How can those grooves on the back of some ICF forms be considered a tornado feature? Does any ICF manufacturer make such claims? I could possibly see some minor benefit if you are using a synthetic stucco exterior without any mechanical connection to the ties, but any siding material that uses screws into the ties, I just don't see it.

BTW, I'm installing brick veneer over the entire house with adjustable wire ties connecting the brick directly to the concrete, so I can't imagine how grooves in the foam would have any effect during a tornado.

A couple of potential hitches. Without thermal breaks, your heat would "escape" into the concrete core that isn't vented to the inside. At a minimum, your surface would start the day a good bit cooler than a trombe wall that is inside the conditioned space. At night, you'd have the problem of the exposed concrete conducting cold into the core. I suspect you'd still have a net plus in Ark, but nowhere near the efficiency of a collector leaning against the wall. http://www.motherearthnews.com/Do-It-Yourself/1977-09-01/Mothers-Heat-Grabber.aspx

Arkie6, My mistake calling it a tornado feature. It is my understanding that the main reason for this feature is to eliminate the air gap due to shrinkage. Also, when i replied i didn't yet know which type of block you were using. However, it does go without saying that blocks without internal groves are many many times easier to separate from the concrete. My intention was to save you the trouble -- your block will probably come off easily enough. That said, it is rather rare, even in commerical construction to feel the need to anchor all the way back to the concrete. Good luck with your project. I am looking forward to learning more about trombe walls. Regards.

TexasICF wrote: "...it is rather rare, even in commercial construction to feel the need to anchor all the way back to the concrete."

What is typically used for securing the brick veneer to the ICF in your area?

It is my understanding that the typical corrugated brick ties used in wood frame construction are only approved for use on wood framing. I know many ICF manuals show the use of these screwed to the ICF ties, but I don't think that is a code approved method of securing the brick veneer.

Another reason for me wanting something more secure than corrugated brick ties screwed to the ICF ties is that I'm on the fringe of the New Madrid seismic zone. If the big one hits, I want my brick to stay on the wall.

STRENGTH TESTING – POLYPROPYLENE WEBS FASTENER TYPE TEST STANDARD ULTIMATE WITHDRAWAL CAPACITY No. 6 (3.5mm) Dia.Drywall Screw ASTM D1761-88 185 lbs·force / 83.9 Kg force No. 8 (4.2mm) Dia. Self Tapping Screw ASTM D1761-88 242 lbs·force / 109.8 Kg force No. 10 (4.8mm) Dia. Self Tapping Screw ASTM D1761-88 274 lbs·force / 124.3 Kg force You will need to consult your block manuafacturer for these tests as these numbers pertain to NUDURA. There numbers show a very significant strength improvement over wood. If your blocks numbers are similar i wouldn't worry about it. That said, i have had inspectors require two screws per regular tie despite the above -- if you have doubts but still want to avoid going all the way back to the concrete i would suggest you use a commerical tie. They aren't cheap but would save you quite a bit of labor. I think we have a few photos on our site but i attached on for you here.

Below (bottom right example) is what I had in mind for my brick ties.  Simple installation for my LiteForm ICF since they are smooth on the top and bottom of the 8" high forms - just lay the 3/16" diameter wire fixed part of the tie between the forms every 16" vertically and every 16" to 24" horizontally as the foam is being stacked.  Set them so the eye part of the wire is flush with the outside face of the foam.

http://www.wirebond.com/adjustrecties.html

Another example here:

http://www.heckmannanchors.com/Submit/262-263.pdf

Another similar option (page 5, Hook Tie & BLT-2):

http://www.blok-lok.com/pdf/catalogue2007/03_masonry_anchors_and_ties.pdf

Looks fine to me. Good luck with your project.