A pitch raise is just like a regular tuning, except, it isn’t. A tuner will typically do a pitch raise tuning when a piano is really flat or really sharp, but it needs to be brought from where it is to a target pitch, usually A440.

If the piano is far enough away from its target, however, any tuning will fall below its target significantly when it brought to said point.

For example, if a piano is resting somewhere at A4 = A4-25cents(flat), then this is pitch raise procedure is necessary. Instead of bringing it just to A4+0cents, the piano needs to be brought to about A4+10cents, respectively from section to section across the piano, and the treble part of the piano especially should be raised significantly by ear or using an electronic or computer tuning program. The treble wire is usually the most responsive to changes so this area often goes out of tune and requires the most amount of work during a pitch raise.