I'm having a sprinkler system installed and the PSI meter in my garage went from 85 psi to about 105 psi. Is it expected that a sprinkler system increases water pressure to my house? If not, is adjusting the pressure release value a reasonable approach to fix it?
It can, if you live in a hot sunny climate and there is no one-way valve to the sprinkler system. Cold water in, or on their way to the sprinkler valves will be heated by the ground or sun, and expand will a little causing significant back pressure.
If you have ever left your garden hose filled with water with the hose bib shut off on a sunny day, then pulled the trigger on the hose end, you will see the same effect. Lots of water pressure.