Before I get into how
to replace it, I should ask, does it really need
to be replaced?
If it is leaking,
then it's simple, It needs to be replaced. See
Boiler relief valve
If it is full of
water, it needs to be replaced, Tap the tank the
back should sound hollow, if not, it is full. if
it is full, that means it will be very heavy, So
be careful not to let drop on your fingers when
you remove it.
The Rest is easy unscrew
the old one and put some kind of pipe dope or tape dope on the threads. (only on
the315 and #30) and screw the new one back in The #109 And #110 do not need and
pipe dope or tape dope they have an O ring that makes the water tight seal. ok
that's it you are done put the auto vent back. turn the boiler drain off turn
the water back on
Get the Air out
turn the power back on.