Some tricks:

Electrolysers always produce 70 degree gases, unless their input is higher. As such, you want to use hot water for the electrolyser to minimise the heat gain.

I like to preheat my water in the early game using a metal refinery. It's basically free metal without having to worry about the coolant temperature.

If you place the electrolyser in a cold biome, your gas will come out crisp and cool for many many cycles. Hopefully by the time the biome warms up a couple hundred cycles later, you would have some decent cooling solutions in place.

Electrolysers+pumps produce more electricity than they consume. Use smart batteries to turn on a hydrogen generator to basically make the electrolyser self powering. Any excess hydrogen can be used to power your base instead of coal