Best way to PID tune bed with heated chamber

[Aurimas]

hi all,

any ideas how to tune bed while heated chamber is on?
tuning separately doesn't really work since the bed is slow to warm up on its own and would not reach 150C
chamber needs to be 120-150C
also fairly slow to heat up.
when both are heating up it faults out few times
after resetting the faults and it has heated up the temperatures overshoot big time.
big time as in 10-20C and the PID is out of the water and cannot control the temperature properly