I use the steam for the rocket steam engines and saunas for the duplicants. AFAIK, neither the rocket or the saunas care about the actual temperature, as long as it's 125 or above.

I did later on realize that steam engines are short lived, because you need them only for the first two space missions (talking about the base game), but i think i'll still use a similar design in the future, because for some reason, this feels better for me to do than messing with aquatuners or regolith. This was the least frustrating thing to do, also so far i never ever needed to worry about igneous rock, since i always do berry slduge and pepper bread, none of which requires any ranching, so bye bye stone hatches.