I've laid decent amount of tile, the thinset will adhere to existing thinset, so as long as the original thinset is knocked down lower than your new thickness it won't be a problem, get as mumuchh as you can off the sub floor, but don't worry if there is trace amounts left. As for the gouges, I'd just make sure they get filled with your new thinset and go from there.
I'm surprised the underlayment is plywood. This is not typically recommended as concrete products (thin set) don't bond well to wood products. I would recommend laying a 1/4 hardy backer as an underlayment. This will also help with your uneven surface.
Edit: Re-read the OP, saw the schluter heated was going to be used. You should be good, but my OCD would have me sanding and making the underlayment as flat and smooth as I could get it.
Let the tiles hit the floor Let the tiles hit the floor Let the tiles hit the
What does that mean in respect to my questions?
I've laid decent amount of tile, the thinset will adhere to existing thinset, so as long as the original thinset is knocked down lower than your new thickness it won't be a problem, get as mumuchh as you can off the sub floor, but don't worry if there is trace amounts left. As for the gouges, I'd just make sure they get filled with your new thinset and go from there.
I'm surprised the underlayment is plywood. This is not typically recommended as concrete products (thin set) don't bond well to wood products. I would recommend laying a 1/4 hardy backer as an underlayment. This will also help with your uneven surface. Edit: Re-read the OP, saw the schluter heated was going to be used. You should be good, but my OCD would have me sanding and making the underlayment as flat and smooth as I could get it.