I got to the point that it is a problem when no item is stacking that is from the same sort of item. Also i have got an nice idea, so you could implement another research to use direct energy converter for the previous fusion reactors so you have not to use turbines and heat exchangers in the endgame -> space efficient and probably also a little bit fps/ups efficient.

I got to the point that it is a problem when no item is stacking that is from the same sort of item.

I don't know what you mean, could you maybe explain it more or send some screenshots?

Also i have got an nice idea, so you could implement another research to use direct energy converter for the previous fusion reactors so you have not to use turbines and heat exchangers in the endgame -> space efficient and probably also a little bit fps/ups efficient.

DECs can only be used with aneutronic reactors. I want to keep the mod realistic.

so that when you want to build more reactors then you need also mor heaters and they don't stack so i wish they could because they use many space in my inventory ^^

Well don't carry around whole fusion power plants then! A single power plant can produce gigawatts, it shouldn't be that portable.

Okay, could you please implement that i can rotate the reactors?

I don't have the original models, so I can't make the rotated textures. Besides, the textures don't look as well rotated. I could modify the code to allow rotation, but the textures can't rotate.

Oh okay, than it is not so nice

I know you don't have made the texture but as if you get the original textures, should this be symmetrical? See picture: https://imgur.com/mMVV8iH

You aren't supposed to put a heat exchanger at each of the outputs. They are symmetrical, though.

One last question that i have is have you planed to implement a building like a condensation tower do get some water back from the steam that you create when you make deuterium with boilers. And the water could 1. be reused as an input to the refineries or 2. you implement a second building thet is capable of moving the water back into the sea where it came from.

That's one of the main disadvantages of boiling water directly instead of using the GS process. It's steam, so the easiest thing to do is venting it into the atmosphere; might as well generate some energy with turbines so it doesn't get wasted.

Yes but the problem that i have with the turbines is that when they can't produce power because you have enough than you don't use the steam and so you don't produce the fuel for the fussion reactors also when you have a 10% or 20% heavy water production. I think it would be nice you implement something like this mod (https://mods.factorio.com/mods/GotLag/Flare%20Stack) to your mod but with a little bit more throughput.

And when you don't want to waste Steam you could upgrade the Flare Stack so you could activate and deactivate with the network through the amount in a tank for example.

You can use the discharge pumps with the GS process to get rid of deuterium-depleted water.