Since I'm pretty new to the DIY'ing, I was hoping someone would be able to help me out...

I have in-floor heating as my primary heating system, which also heats my DHW through an indirect. The boiler has been sitting around 33-35psi for the last little while, causing my PRV to release water on a semi-regular basis. I originally thought my expansion tank was the issue. It's 9 years old and was full of water. I replaced it a couple weeks ago, and the boiler pressure evened out at around 20psi.

Now, about 2 1/2 weeks later, my PRV is leaking again. Was hoping it was just a faulty valve after the workout it got before, unfortunately I checked my boiler, and the pressure is back up to ~33-35psi. Any thoughts or ideas on what could be going wrong here?