Pipe plug "fixes" leaking PRV

JUGHNE

Call was for 80+ year old dripping CI radiator; only leaked during heating season.

No, we can't take it apart to fix nor easily buy a new one.  Go for a look at the boiler and of course the pressure gauge is shot, sitting stuck on 40 PSI.  Look to open the PRV and find a 1/2" pipe plug in the bottom drain opening!!  It is a 3 year old B&G combo fast fill & PRV.  So the eventually the storey comes out;  3 years ago something dripping/leaking in bsmt--local HVAC guy looks at it & orders new--helper comes to install later--all is good--lady calls him back 30 minutes later--something still leaking--helper fixes leak with 1/2" ips plug and all is good again. 3 years later radiator leaking. Jump to yesterday: remove plug, drain 1 gal water, pressure drops to 16 PSI ,gauge was actually good, fire boiler: pressure up to 25 psi in 30 seconds--of course compression tank completely waterlogged.  HO says that gauge pegs out over 80 psi in the winter time.  I think their Angels are with them all the time and gave the warning at the leaking kitchen radiator.

Boiler is Bryant 8W-26 C LG (now NG) SN 21177 180,000 BTUH.  Surprised by Install book being inside cabinet "effective 7-1-54".

100 year old house, gravity piping, all CI radiation, had pump added with this boiler.  Of course could just do a cleaning, get air in the tank, flush out boiler, (probably never done in 60 years)  and leave out the pipe plug!!

HO show interest in higher efficiency, I don't believe condensing unit justified for this CI system.  The only item I'm uncomfortable with is the Gas Train----Basco valve with t-couple pilot--Bryant Diaphragm main gas valve (1/2 A634 SN:9KT) -- adjustable water temp control limit control (not electric) "Titan T-43-B" which has 1/4" Al tubing to act on the diaphragm of main valve.  It does light off nicely though.

Any suggestions--total replace--clean w/new gas train.  Thanks! JUGNE