CPAP Expiration

Does anyone know how long a CPAP is good for? In other words, must you replace it every so many years? I am really having trouble with compliance for my job. I have been using it over 4 hours a night but I am still missing the mark of 70%. The employee health doctor thought there might be a leak in the equipment causing the issues.

Many insurance companies will cover cpap replacement every 5 yrs. How old is your machine?