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.
Sprinklers usually drop your pressure while on but other than that there should be no change in pressure. I am thinking of lawn sprinklers.