At the moment, players going solo or being removed from a party loose their heat.
This is totally wrong. There is no valid logical reason for this; so it must be coding issues, to be overcome.
Lost heat is especially annoying, if a party leader is AFK for a long time, since there is no way for others to vote him away and they can't use an elevator to get their heat. In this situation heat is basically lost for everyone.
Also, when a party leader is an evil person and removes players for no proper reason, he also removes their heat and is doing them wrong twice that way.
No, this is intentional.
If you would like to see this changed, make a thread in Suggestions, but this is not a bug.