Heat Transfer:
Click on someone on your team and give to them, by a percentage, the heat you have on that stage.
Maximum heat limit:
When you have max heat, you no longer obtain any. Therefore evenly distributing heat to those who need it.
In Depth:
Probably suggested before, but this wouldn't be any sort of item.
You know when you click on a persons portrait? How you can click their energy symbol and hit add to tab? Perhaps, on that thing, you can also say "Transfer heat." and then when you click on that there will be a drop down of percentages, probably going up in 5's. That way, at the elevator, if I have max heat, or maybe if I just don't care about having heat and he only has 1 item and needs that extra boost to get it from 9 to 10, I can give him my heat and presto. Happy.
Maybe, at least, when all your gear hits Heat level 10, you no longer obtain heat, and therefore you no longer take heat away from others in stages. That way, when heat is distributed evenly, you don't suck away the heat from those who need it. I mean, you don't need it, why take it from others who do?
Just a small suggestion.
You know I've been wondering if at some point in a level if I'm going to stop collecting heat, because I get my large ying yang shaped swirly vortex of warmth, but once it reaches that point, it doesn't change. Maybe if anything is implemented with the system, we could see some numbers like typical experience collection? Not on the gear at the end of the phase, but just as a total above the lovely swirling fire of doom.