The burn as is seems to me to suffers from a greater problem... Because each point of burn inflicts one point nonlethal damage per level that cannot be healed until the next day, it means that average kineticist cannot use more burn per day than 4.5+Con modifier. Which at higher levels is about two wild talents/metakinesis use, three or four with Constitution increasing effects. 20th level character focused on Constitution can reasonably have ability score of 36, which gives +13 modifier - about 17-18 burn points per day. Seems ok, allowing to use the max boosted powers three times per day. Assuming you don't do anything else... And you don't mind fainting ever other round when an opponent stabs you for 1d6 damage dropping you current hit points below nonlethal damage already suffered...
I 100% agree with this. Burn needs to be overhauled, probably with set damage values.