Need to remove ceiling grill cover
Disconnect electrical wiring
Remove the 4 hold down bolts in the corners
Lift old unit up and out of roof opening...best done by 2 people
Remove old roof gasket
Clean up roof area
Install new gasket on unit
Set unit in roof opening......best done by 2 people (make sure gasket is properly positioned)
Install the 4 hold down bolts in corners----tighten evenly in 'X' pattern until new gasket has been compressed by half (new gasket 1" thick....tighten until it's 1/2" which is roughly 40 inch pounds of torque----that's INCH Pounds not FOOT pounds. Bolts should be 'snug')
Connect electrical wiring