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In most cases the water pressure into the boiler is controlled by a feed valve
It looks something like this
Under normal operating conditions it will automatically feed 12 to 15 psi into the system
One possible exception is if your system is filled with anti-freeze
I see that on boiler, are you saying it could be bad
If the one you have is identical flip the lever on top so it's straight up. If you don't hear water running it may be no good. It's also possible you have a bad pressure gauge. We always verify the accuracy of the boiler gauge with our own gauge. Do you here water rushing through the pipes when you turn the heat on?
the one i have does not look exactly like this one, it has no lever on it. i do hear water running through the system when i call for heat, but shuts down, i assume because there is no pressure.
Hearing water indicates there is air in the lines. If you want to tackle this yourself the first thing you need to do is get a pressure gauge 0-100 psi and a fitting to adapt the gauge to a female hose connection so you can screw it onto one of the hose bibbs (faucets) on the system. What color is your feed valve?
How old is the system (if you don't know guess)?
There's a good chance the feed valve is plugged with rust. Does it have any levers on it at all?
Or a thumb screw on top
there is some kind of screw on top
OK, the screw is likely the fast fill feature (like the lever on the one in the picture). You would crank it down to boost the pressure BUT if you do the feeder may no longer accurately control the pressure once you return the screw to the original position so you need to be prepared to replace it. Here are instructions on how to purge the air out of most systems but be sure to get your gauge before you try this. The pressure must stay below 30 psi or the relief valve will leak.
A purge station is typically a shut off with a hose fitting above it. There can be 1 piece purge stations where both the shut off and hose fitting are combined in one piece. Or it can be a separate valve(shutoff) with a hose type "faucet" (we call it a boiler drain) above it. They are usually at the boiler on the pipe above the circulator pump. You need to determine which one goes to your problem area. I have seen them in old systems some distance from the boiler on the heating line (pipe). You need to shut the valve attach a hose to the hose fitting then open the hose "faucet". Some all-in-one fittings close the valve and open the hose at the same time so be sure your hose is attached first if you have one of these fittings. If you have zone valves with multiple purge stations all the zone valves should be opened manually. If you have zone valves and only 1 purge station then you need to open the zone valves one at a time and fully purge a zone before opening the next valve and closing the valve you just purged. You also need to jack up the pressure while you are doing this but you need to keep the pressure under 30 psi. This is done by increasing the pressure at the feed (pressure reducing) valve. Some types have a lever that you flip up from a "horizontal" position to straight up. This is the easiest type to use. Some require that you tighten the screw at the top of the valve. You should be warned that if this valve hasn't been touched in a while disturbing it in this manner can cause it to fail in which case it will need to be replaced. This device is located on the water supply line to the boiler. Be sure to turn the power off to the boiler while you are doing this. When you hear no more bubbles coming out of the hose for several minutes you shut the hose off at the same time you return the feed valve back to it's original position. Then open the shutoff. Be sure the pressure on the boiler is between 10 & 15 psi when you are done before you turn the power back on. The boiler you have has no bearing on this process. It is the same what ever type you have. Having said all that this is not something I would recommend that you try yourself unless you feel very confident about doing it. You may have to call a plumber anyway if the feed valve fails.
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