The Pressurised Fluids mod compresses and decompresses various fluids; for steam they have specific temperature ranges that can be compressed. They ship with the temperatures for the default steam, but for a non-standard temperature like the 270° steam you create a little custom work is required to register it.

Lovely_Santa, the author, has kindly agreed to integrate on their side, but they also provide an API to register the steam temperature yourself during the data phase if their mod is installed. Since having you control the temperatures is relevant if, say, you ever introduce more than one temperature or, oh, had a startup setting for how hot the steam was...

https://mods.factorio.com/mod/CompressedFluids/discussion/5ed970383059ad000b654f30 has the discussion, and explains how to register the temperature. It should be fairly simple -- just that couple lines, plus a check for their mod, and done.

I'd appreciate the integration. :)