if you lose psi over nite and it is cooler out side, that is ok, but when it heats up the gauge should climb back up
you have a leak.
the obvious places to check first are, valves, check the packing nut, notorious for leaking
valves again, valves leak threw, so you need to disconnect and cap off
if your gas piping is already hooked up to the boiler
STOP...do not pressurize the gas regulator STOP.....
disconnect the piping and cap it off THEN test,
you will destroy the gas regulator if you over pressure you gas line
finding ''seepers'' is a royal pain in the ass, mix a spray bottle with soap/water spray a fitting and stare at it
a seeper will not blow a big bubble but will blow a buch of little bubbles
note*****anywhere you have a valve, the valve must be capped off because valves leak through