With the Iridium Boilers
?
'Nother thing is Ic2 provides Coolant Cells, maybe some sort of "liquid Coolant Cell"
It'd be interesting to see LP Iridium Boilers being Solid Fueled and the HP being Liquid.
Also, do you think liquid Glowstone/Redstone is any hot?
Actually, I'm thinking of diverging a bit from what Railcraft does, in that regard. Instead of the fireboxes being liquid or solid-fueled, you can place either liquid
tanks or solid fuel hopper blocks as part of the boiler multi-block, and perhaps even let you combine the two. As for molten glowstone/redstone, I don't know how hot they'd be, really. I mean, glowstone -is- native to hell and it seems that, in Minecraft, light = heat. However, if we're talking about molten glowstone
dust, that wouldn't give off much heat, I'd think, since melting down a powder is significantly easier than melting a solid block.
Redstone's conductive, yes, but conductivity doesn't really equate much to heat in terms of the molten variety of the material. I might could use them for a few aesthetic things, like lights that can be part of the boiler structures; if you want them to be always-on without a redstone signal, you'd need to fill both buffers with molten redstone -and- glowstone, kinda like a glowstick.
Also, I'm not going to divide them up into simply "high-pressure" and "low-pressure" boilers. How much pressure a boiler can withstand will be dependent on the material its made with. If you make a boiler out of steel, it'd be less durable than one made out of saaayyyy, tungsten. As for secondary coolants, that might be a nice idea as an emergency stop-gap measure if your boiler, for whatever reason, runs out of water before fuel, leaving it dry, but still incredibly hot. Though, I'm thinking...perhaps you could literally pour water on to the boiler to cool it off, while evaporating the water. You could also do the same with ice, and provide more cooling at the same time.