pressure reducing valves

According to Canadian NPC, provision must be made for thermal expansion when check valves or pressure reducing valves are installed. Is the T&P relief valve sufficient to meet this requirement? Or must an expansion tank be installed. I always install an expansion tank when check valves are...

Long time lurker, first time poster here... I'm looking at add a PRV to an existing underground sprinkler system that was plumbed using 1" PVC. For ease of maintenance, I'd like to mount the PRV above ground on the riser that holds the PVB. Seems pretty standard fare except...I'm not sure how...