Regardless of the what the original system was, system MUST be able to withstand 3bar pressure.. PRV is set to 3 bar so one does not have an option but to ensure system will be ok at that pressure.
PRV is meant to lift at 3 bar. I would check the PRV at service intervals to ensure it operates. If the PRV is never checked (saying--- I am not touching that as it will start leaking moment I touch it) the PRV seat can stick to the metal, then valve will not operate at 3 bar but MUCH higher with possible damage to other parts. This is not figment of imagination, but have seen this often. So, I always operate the prv to check it lifts and discharges. If it starts to leak, well then have ready supply of replacements and easily replaced.