Running PEX for Future Hydronic System

I'll try to make a long story short ...

I'm removing my homemade handfed stove and installing an underfed stoker in my garden-level basement (4' concrete walls). Prior to installing the stoker, I decided to lay ceramic tile under the stove and on the walls near the stove. In the process, I tore some paneling off the foundation wall, and by accident, removed some sheetrock as well.

What I found was that my foundation wall is not insulated . They just ran some 2x4 furring strips horizontally along the foundation wall (one at the floor, one at the 2' level, and one at the 4' level). I believe that I should insulate this space, so I tore the rest of the sheetrock off. Should probably put cement backerboard on anyway for the tile substrate.

Here's my question: I can see that down the road a few years, I'd like to put a coal boiler outside, to avoid the mess in the house, hauling coal/ash, etc. Half of my house has a crawlspace, so running PEX would be easy there. The basement would not be easy, unless my idea to follow would work: What if I glue 3/4" foil-faced foamboard against my foundation wall, attach 1/2" PEX tubing to the foam horizontally every 8", and then lay another 3/4" foam board between the PEX? Cover all that with cement board or sheetrock, then tile the wall.

Eventually, I'll do all the basement foundation walls that way, working my way to the crawlspace where I can put my manifold, etc., and them head outside to a boiler someday.

Do you think I'd have enough heating capacity/PEX if I do it this way? The basement is about 24'x24'. I could insulate the foundation wall on 3 sides, in 2 different zones, less than 250' of PEX for each zone. House built in 80's, R-11 walls, poor windows that need replaced, but pretty efficient overall. I heated the house just fine with a handmade stove and about 5 tons of coal last year. Other than a coal stove, my house has electric baseboards, which I hate to run, as the electric meter and bill goes crazy when they run.

Any thoughts? I've got some free 1/2" barrier PEX tubing, and the foamboard needs to go in the wall anyway. Maybe I could get by without having to run PEX on the floor later for much more expense and hassle?

Thanks,
Steinke

Radiant walls also give you that radiant heat feeling. Not as good as radiant floors. In any case you should plan on insulating the floor. If radian floor installation is not possible the walls are the next best alternate. Any radiant installation will work better with aluminum distribution plates. You should use them. You need to do a heat loss calculation to determine how much tubing to install and where. Either the floor or the wall radiant emitter can be designed to meet the heat load loss of the basement. The key is designed. It's not something for SoP engineering. SoP = Seat of Pants.

Thanks Yanche. I don't know nearly enough about hydronics at this point to jump into design. I just know that I won't get another chance at running PEX in this wall, as I'm going to be tiling over it. I can physically only get so much PEX in this wall, so any design that showed needing more PEX than the wall will hold will just mean that I need pex in the floor or ceiling too.

I think since the tubing is free, I'm going to go ahead and stick some PEX in the wall before I tile, about 8" OC, and leave the ends accessable to grab when I decide to tackle the other wall another day. If it turns out I never get a boiler, then there's just some unused pipe in the wall. If I put a boiler in someday, and I need more tubing to heat the basement than can be placed in the walls, then I'll deal with that then.

Good call on the aluminum diffuser plates. What little I read indicates there are a must.

Steinke