so, I already resolved the issues; the root of the issue was that 'heat_capacity' is per-temperature-increment (which most people use as degrees C). There was no documentation about this anywhere in the API or modding info; I finally stumbled across it in a fluid mechanics guide in the player's portion of the wiki. I had incorrectly assumed that 'heat_capacity' was the total energy of one unit of fluid at 'max_temperature', and thus the amount of heat needed was quite astronomical; about 8000 times more than it should be. The other aspect I realized was that vanilla water is 250 liters per unit, if the heat_capacity of it is to be believed, thus 1 unit of liquid = 0.25kL, rather than 10L as I had originally assumed.
Concerning making sure the temperature is correct for the recipe, I wrote a script that checks 15 times per second for fluid in a separate 'intake' entity, and if enough fluid is present of the right temperature, it removes the appropriate amount from the intake entity, and inserts the corresponding amount into the blast furnace (an assembler type entity). If the intake fills beyond a certain point with air that is not hot enough, it removes some so more can come in. The linking process for it is essentially the same as Uranium Power's access port linking (I admit I looked to it for ideas on how to do this). I have to say, the number of nil and valid checks one must do in this is pretty silly, but that's probably just me coming from a strong typed language background...
Because of the massive amount of materials a blast furnace consumes, I also wrote a script for it to pick up valid items that are adjacent, which is also processed 15 times per second. So far, it's (finally) all working out nicely, now that i've uncovered more of the silly API's tribal knowledge. Armed with what I have now, I can jury-rig around most any further obstacles I run into, I believe.
Thanks for your time and you mod! It's a lot of fun, and I look forward to how it further develops. My only suggestions for it would be 1) move it further up the tech tree + split out some of the techs a little more, 2) increase the amount of depleted uranium needed per pellet, as currently it's pretty trivial to replace all ammo with the (somewhat powerful) depleted uranium rounds.
oh, and increase the decay rate on the uranium; giving it a base-line decay as well that happens even when it's not under any load.
But, those are only suggestions; the mod is already a blast and really cool
PS: Rseding said he has written up some code for allowing recipes to have heat constraints on liquids, but it's pending approval by one of the leads, who has been super busy with multiplayer lag-hiding and end-game stuff. It'll be in the game in some build relatively soon methinks, but that may yet be a moth or three, depending on priorities. Just thought I'd give you a heads up