Bread breaks in the middle while in the oven

I would like to clarify a couple points from the question and the comments here. First of all, remember that flour (wheat or spelt) does not contain gluten. Gluten only forms as a complex protein once two simpler proteins in flour, gliadin and glutenin, are hydrated. And while not all of the protein in flour will form gluten in the presence of water, the overall protein content in flour is usually used a proxy to represent the gluten-forming capability of the flour. So flours that are higher in protein typically form more gluten in the presence of water and kneading.

Now, having said all that, spelt 630 flour actually contains much more protein (~16%) than wheat 812 bread flour (~13%). While 3% protein content might not sound like much, it makes a significant difference when making bread.

Again, your spelt 630 flour will generate MORE gluten in your dough than a typical bread flour. It is considered a high-protein flour.

I would suggest that much of your problem might stem from over-kneading your bread. Gluten in dough is a bread's best friend only up to a point. If your gluten network in the dough is over-established, your baked bread will bake-up dense and dry and could conceivably split through during baking.

So a dough with overdeveloped gluten would be something like the proverbial hardwood tree in a storm - the tree that breaks because it doesn't bend.

While I believe the scoring point made above is absolutely relevant, I don't think an un-scored loaf would split through if there wasn't a problem with the bread dough itself.

I think the best solution to your splitting problem would be to mix-in some different lower protein flours to drop the protein content of the spelt flour. If that option is off the table, then consider kneading much less (probably stay away from the mechanical kneading unless you're making batches too large to manage by hand). If you can manage the kneading by hand, you should feel that magical dough elasticity that signals when it's time to stop.

Is it related to no gluten and the fact it's obviously not as elastic as your normal wheat bread?

No, it isn't. First of all: spelt is not gluten-free. It is very closely related to wheat, and has lots of gluten in it.

Second, you make it sound as if you suspect that spelt bread will always have a split crust. But this is not the case, spelt breads don't always split.

I would look at the usual culprits for split crusts, there are many of them, and work the same way on spelt and normal wheat. They include improper scoring, improper rising (especially using too much yeast), wrong oven temperature, or doing nothing to soften the crust, to name just a few. It is impossible to guess what goes wrong from your description. If you need such high quality that a split crust is a problem for you, you need to learn the basic process for making yeast leavened breads, for example from Peter Reinhart's books.

I have done some investigation, and this is what I found. The gluten in spelt is water soluble; it is degraded by heat and is easily broken down by mixing action. Wheat gluten, in contrast, does not break down in water and only relaxes when exposed to heat and seems to get stronger as it is mixed – bakers refer to it as “developing the gluten.” If you over mix spelt, it will break down. If you over mix wheat, it will get stronger.

This basically means I am using the same kneading time for spelt and wheat alike, which means in all comparison I'm doing it right in wheat but overkneading in spelt... :(