Pressure Drop
Your issue may be related to volume and not pressure. You may have a strainer in line prior to the RPZ. If it has any debris it will drop volume which coul be related to you having problems at full capacity.
This is General information for owners in all states. It pertains to the testing of any and all backflow devices. All backflow devices are to be inspected by a state certified inspector. Most states are generally requiring a once a year inspection. Our state of Indiana requires inspection every...