Okay so I went back to a dead server and checked out the explosions again. I will retract the flame statement and will agree that they could look better BUUT I still think their is a 'Heat Wave', its just hard to notice.
I was tossing around nades like mad and I couldn't replicatethe heat wave I remembered so I thought I was going crazy
but then I equiped the rocket launcer and fired it at the Lambda on the day Tat map (Mos Entha I believe). The explosion definately warped the image of the lambda and also a Watch Tower that was far away too.
The key to seeing said warping effect is to be a good distance from explosion (25meters plus) and using a grenade/rocketlauncher/APM's not emps, medic nades, or det packs.
If you're in a AT-ST you can also see warping effect if you change camera view and fire the grenades and watch the explosion.
AT least this is what I see... I'm running on a 23" Widescreen Monitor with a fast refresh rate too...