Water has dissolved air in it that bubbles out and gets trapped in
radiators, not allowing the hot water to flow fully. Each radiator should
have a little bleeder at the top that operates with a little wrench or
screwdriver. These bleeders might also be at high points of the piping
where the pipe goes up and then down. Repeated bleeding is needed till all
the air is eliminated. Since a boiler uses the same water over and over,
eventually, all the free air gets eliminated.
If your system is typical, then, no it shouldn't use much fresh water.
Maybe the relief valve is leaking, or blowing off for some reason, but when
fresh water is introduced into the system, with it comes more dissolved air.
Then the bleeding must take place again and again.
Again, if your system is typical, the pressure gauge should read about 14
psi. If it's much greater, then the automatic fill valve is faulty. The
temperature is a harder call, since systems vary so much, but if it's more
than 200 degrees, there's probably a problem. You might also simply have a
leak in the piping that's undetected.
I continue to have to bleed the system. I do realize introducing new water
brings air, so I must install some auto bleeders. Where do you recommend
them going? I get a bang after the circulator pump turns on after approx. 10
seconds. The bang seems to be coming from the closest radiator to the
boiler. Today I noticed the system pressure dropped to 11 psi.. The
climate is a little milder lately and the boiler has run less. I don't know
if I am only watching it more because of the bang or if the psi has done
this in the past. But I always thought it stayed at 14 psi. Temp set at
180*F. I also thought the accu-stat may have been at fault so I turned it
up to test for the heck and when set at 220*F it boils near 212*F which
would be correct.
How do you determine how full the steel non-bladder tank is filled?
Thank You, Mike
If your expansion tank is waterlogged, the pressure relief valve will run
every time the boiler kicks in. Can you see where the relief valve drains?
The automatic bleeders are usually placed near the boiler, on a high area
of the main feed line.
If you have the non bladder type of expansion tank, you should not be using
automatic bleeders. If you have problems with air in the radiators it is likely
from low pressure, not using a boiler fitting on the boiler, not using an ATF on
tank, or not properly piping the tank to the boiler. You have to continuously
separate and return air to the expansion tank or you will get air bound in the
radiators and water logged in the expansion tank.
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