Find a boiler (hydronics) contractor that can, when asked to, explain what an outdoor boiler reset control is and how it can help your comfort issues and also potentially save you on your heating bills. When you find one that takes the time to explain things to the point where you feel educated..... that's the one you want to hire.
For your reading, search "outdoor boiler reset control" on the internet.
This information is all assuming that the new boiler that was installed 5 years ago is a standard efficient cast iron unit (vented into a chimney with galvanized pipe) , not a high efficient modulating unit (vented with plastic/PVC piping).
Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.