#OxygenNotIncluded early-ish inexpensive heat deletion: It began with a reservoir filled with ~24C water. Once the water leaving the reservoir exceeds 77C, it is emptied into another reservoir, to be used by electrolyzers for O2&H2 generation. The reservoir is set to 0/90, so that once it has emptied, it will be refilled with more ~24C water (the pipe & shutoff to the right of the refinery).