you got good insurance???
Just In my humble opinion...
maybe you have done plumbing for years and years, I dont know.
but being on the 22nd floor of a high rise building is not
really the best place to be learning the plumbing trade....
or fooling around with anything in general.....
hopefully , you are not messing with the water system too?
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fools rush in where wise men fear to tread...
I dont go above 5 floors high and never will just becasue of the HUGH liability that can incur from just one very small leak....
If you have not done a lot of plumbing, it could cost you or your insurance company a large bundle , and they arent going to be happy.
niether are the neighbors below you either.
I apologise if you are capable of doing this work, but
all I am saying is it might be better to cough up some dough to the maintainance staff of the building and have them do this for you,
or call a plumber willing to risk it all,
then you are off the hook if something goes wrong.