Customer called us out for a water hammer that while I was their they showed me on their phone but had the water running in the shower prior to my arrival. Once there i was able to observe the pressure rise on the prv from 60-100. Opened the laundry sink and it dropped right back to 60 and started to climb again. Prv is new main valve is new. Expansion tank is full of water and should be replaced this will allow the expansion air being created while heating water. Customers t&p valve was pressed against the wall and was unable to release any of the pressure if needed trapped in the system during heating. Customer did not want inspection today and is calling insurance to see if they'll help with payment on the expansion tank replacement