Heat is needed only for germination and not recommended for growing on. You'll find several discussions here about this vital point.

Standard recommendation is once the seeds germinate they should be removed from the heat and provided with cooler growing temps to avoid cooking the young roots (among other things). Any covers should also be removed at the same time.

Heated soil not only risks the roots but encourages leggy growth and soil fungus problems. 45-65 or 70 is considered the ideal growing range. Cooler requires added heat, warmer requires active cooling.

Dave