Your hot water boiler or furnace may have a stuck pressure and temperature gauge.
Above are some pictures of boiler gauges, you would think that something
as important as your pressure and temperature gauge would be right in front,
and easy to read, In some cases it is, in others you need a mirror, and need
to bend like a pretzel to read it. So you will need to locate your gauge,
one part of the gauge reads the pressure the other part reads the
temperature. either one of them can become stuck. First the pressure. it
should read 12 psi to 20 psi.
I just removed one the other day that is
still reading 12 psi (stuck at 12 psi) the boiler really had no pressure at
all. But how did I figure that out? I needed to test the
boiler relief valve, to be sure it
was not stuck (this is very very important ) When I pulled the tap, just a
little water came out, this could have been because the relief valve was
clogged, so I had to investigate a little further. I turned the power to the
boiler off and hooked a hose to the boiler drain on the bottom of the boiler
and opened the drain, water came out but with no pressure, and the fill
valve did not let water back into the boiler. so now I decide to drain the
whole system, (because I know I have to make repairs) I remove an auto vent
on the top of the boiler to let air in to the system so it will drain, the
gauge is still reading 12 psi, so I had to replace the gauge and the
fill valve and the
expansion tank. to get this boiler
How to test your gauge.
First see what the gauge is reading, write it down, (both temp. and Pressure) Then turn the power to the boiler off, then turn the water off. then hook up a hose to the boiler. and let just enough water out to make the gauge move down to zero. if the gauge does not move it needs to be replaced. if it moves. stop draining water and turn the Water back on, If the pressure goes back to the 12 psi to 20 psi, the pressure part of the gauge is fine. Now for the temperature. leave the boiler off (if it is not heating season) for a few hours to let it cool. (it may not go below 100% f this is normal then turn it on and wait till it shuts off by its self, then check the temperature it should be below 200% f . If it gets higher you may have an Aquastate problem Or your aquastate is set too high. If it does not move at all it needs to be replaced.
Solve your boiler pressure gauge problem faster by using the Open Dialog Service.