What is the maximum water pressure for a domestic dwelling?
How will this affect boliers?

What is the maximum water pressure for a domestic dwelling? About 60PSI should be about tops and your boiler will handle that. Good luck Tom

Most all codes in the US say 80psi max. As for your boiler, it depends on what you are calling a boiler. If it is a boiler for hot water heating, it needs to have a pressure reducing valve to bring the pressure of the boiler down to roughly 12psi.

Yeah, 80 PSI is a max. and anything near or over that requires a pressure reducing valve be installed. Boilers, as mentioned by MGD77 should have a pressure regulating valve that sets the pressure at the boiler between 12-20 PSI (maximum). Here, as temperature increases (and thus pressure) you will see a fluctuation in pressure (usually handled by the expansion tank) that can exceed the 12-15 PSI the typical boiler pressure regulating valve is "factory set" at, but this range.. 12-20 PSI is reasonable as a whole! Anything beyond that can be a problem for cast iron radiation systems, for sure!

Mark