The boiler relief valve or the blow off
valve is a safety valve that protects your
heating system from building up to much pressure
and possibly blowing up.
It's a very important part of your heating
Some times the relief valve or blow off valve
will leak, and naturally people assume that it
is because the relief valve is defective.
Sometimes this is true, and if it is leaking you should
replace it even though it is leaking for other reasons.
But it may just be doing it's job. There are 5 reasons a
relief valve leaks.
Click on any image to see a larger image.
The First reason:
Nothing lasts for ever, and a
relief valves or blow off valve
|The second reason:
The expansion tank on a boiler allows
the water in the boiler to expand. Water can not .....
The third reason:
The pressure reducing or
fill valve for a
boiler is set to only allow 12 psi in to the
boiler. If this valve fails .....
|The Forth Reason
Some boilers have a hot water coil, sometimes called a
tank less water heater. Some times a coil will develop
The fifth reason:
The aquastat or aquastat relay, This is a very
important part of your heating system. the item in the picture to
the right .....
Boiler gauge settings:
The pressure should be
from 12 psi to 18 psi
The Temperature should be between 160
and 180 degrees f. but can be up to 200
To replace a relief
valve. Turn the power to
the boiler off, let the
boiler cool, turn the
water to the boiler off,
remove the drip tube
from the outlet side of
the relief valve. (this
must be put back after
the relief valve has
been replaced) Drain the
pressure off the boiler,
remove the relief valve,
make sure you replace
the relief valve with a
boiler relief valve of
the same rating, DO NOT
USE A WATER HEATER
RELIEF VALVE ON A
BOILER. after you
replaced the relief
valve and put the dip
tube back on, turn the
water back on and
purge the system,
then turn the power back
Don't want to try this
yourself? Use the
See a stuck boiler gauge
It's very important, that you read and
understand the instructions written on the
boiler relief valve tag, the tag is on the
relief valve under the lift lever.
on this tag is small, and many times, even
though, the first thing printed on the tag is
"DO NOT REMOVE THIS TAG", the tag is removed.
So to help you read this very important
information, I typed it out, so that you can
Please follow the following links,
to read both sides of the boiler relief valve
Read the front of the
boiler relief valve tag
Read the back of the
boiler relief valve tag