If you are learning to play the piano from scratch or perhaps buying an instrument for a child, it is advisable to take along a qualified Tuner / Technician to assess the pianos you may be considering buying.
A new piano may be guaranteed for faults in manufacture, but if it isn't matched to its intended use and environment, it may be difficult exchanging it for a more suitable one without financial penalty. As with all major purchases, you want to get it right first time.
A good quality new piano should last many decades if carefully selected and regularly maintained.
When considering a used piano, even more care must be taken. Components wear and deteriorate with age and the cost of restoring a very worn piano can be high. It is always a mistake to buy a cheap ‘pub piano’ with the intention of spending some of the money you may think you're saving on a little restoration. This scenario nearly always ends in tears!
Always buy the best piano you can afford. The sound and touch should be even as you play up the keyboard. It should be free from excessive mechanical noise and should be in reasonable tune.
If you can, check that the pitch is at A440. This pitch is the international standard and the one pianos of all ages are designed to be tuned to. If you intend to use the piano with other instruments, it is essential the piano will tune to A440. If a piano is flat, i.e. low in pitch, the only way to know if it will go to concert pitch for certain is to have it assessed by a tuner and tuned if necessary. Only then will you know if the tuning pins and strings will take the extra tension. A semitone pitch raise to A440 puts the equivalent of ½ ton of extra tension in total on the 230 strings of an average piano.
60 Stony Lane