This will depend on the humidity of your room at the time. If it is at 40% to 60% you might not hear any change, however a prolonged period with the system off at 0% to 40% and or 60% to 100% will cause the piano to go badly out of tune.
Note: If your Piano Life Saver System has been turned off and your piano is booked for tuning. Allow 3 weeks for the piano to settle again before tuning. So you may need to re-book your tuning.. We recommend not turning off the system at all. Use a lightening protection adapter for your system.
Call Gary on if you are worried about you system. (7am to 7pm WST Australia) or better still send me an Email firstname.lastname@example.org