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The boiler relief valve what it does, why it leaks
and how to replace it. But, as always, the safest and most comprehensive solution often comes from the help of a professional plumber. You can find one in you area by
filling out the short contact form here.
The boiler relief valve or the boiler 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 system.
Relief valve on boiler not holding? Then, this could be true. It's also possible you'll need a replacement, so try searching this site and others for 'replacing pressure relief valve on boiler'. Sometimes leaking just means it is doing its job, however. There are 5 reasons a relief valve leaks.
The first reason is, it is defective or just old.
The second reason is, the boiler pressure is to high because of a bad expansion tank "See Expansion tank"
The third reason is the pressure is to high because of a bad
fill valve.
The forth reason is, the pressure is to high because of a leaking coil or a leaking indirect hot water maker.
The fifth reason is, the boiler is over heating and making steam.
What should the gauge on my boiler read? |
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The First reason:
Nothing
lasts
for
ever,
and
a
relief
valves
or
blow
off
valve
will
go
bad.
A
boiler
relief
valve
needs
to
be
tested
every
three
months
to
be
sure
it
is
operating
properly.
if
you
have
not
checked
yours
out
for
a
long
time,
you
should
have
it
checked
out
ASAP. |
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A boiler relief or blow off
valve, that has
not been tested in a long time may become rusted closed, causing it to
be as dangerous as not having one at all. You can test it yourself but
it can be dangerous you can get scalded by the 180 degree to 210
degree water, Water this hot will cause a very serious burn. and in
most cases once you pop the lever, the valve will not seat again, and
the valve will need to be replaced. if you want to do it your self
turn the power to the boiler off and leave it for about 2 hours before
pulling the lever. Check the temperature first. |
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The second reason:
The
expansion tank on a boiler allows the water in the boiler to expand.
Water can not be compressed and when it is heated it expands. the
expansion tank has a diaphragm with 12 pounds of air pressure in it.
This allows the the water a place to go when it is expanding. over
time the tank can become water logged or the air leaks out of the
tank. when this happens the water has no room to expand, so the
pressure builds up and the relief valve will start to leak. the best
way to test to see if this is the reason your relief valve is leaking
is to watch the pressure gauge (see
stuck pressure gauge) when the boiler is heating if the pressure
builds while the boiler is heating, the tank is bad and needs to be
replaced see
expansion tank |
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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 it will
allow the pressure in the boiler to reach 30 psi or higher. causing
the relief valve to leak. if your gauge goes over 30 psi and the
relief valve does not leak, turn the boiler off and call a plumber
ASAP. This is a very dangerous situation. To test for this problem,
turn the boiler off, wait till the boiler is cold, drain off some
water till the pressure drops below 10 psi, then with out turning it
back on, wait to see if the gauge starts to go up again if this
happens it is probably the fill valve (it may also be
Reason Four) to eliminate the fifth reason turn the water to the
boiler off, if the pressure does not raise with the water off, it's
the fill valve. if it still raises with the water off, it is reason
four. |
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The forth reason:
Some boilers have a hot water coil, sometimes called a
tank less water heater. Some times a coil will develop a pin hole in
it. If this happens it will cause the house pressure to seep into the
boiler causing the the relief valve to leak. to test this turn the
water to the coil off and see if the pressure stops raising. An
indirect water heater. can become defective and cause the same thing
as the coil. to test this turn the water to the tank off and see if
the pressure stops raising. |
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The fifth reason:
The aquastate or aquastate relay, This is a very
important part of your heating system. the item in the picture to the
left is a secondary aquastate, it's purpose is to back up the main
aquastate, if it fails. Most area codes require this aquastate be
installed on your boiler. if you don't have one you should have one
installed. Now if the aquastate fails, the temperature of the boiler
can raise to a very dangerous point, causing the relief valve to blow
off, this is an extremely dangerous situation and must be corrected
immediately, turn the power and gas to the boiler off and call a
plumber.
Find a local Plumbing and Heating contractor |
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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 degrees f.
See a stuck boiler
gauge
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 on.
Don't
want
to
try
this
yourself?
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