Steam Boiler Help

OK, some more details.

Why is the pressure so high, radiation to boiler mismatch, radiator EDR vs boiler Square Feet rating. Is the gauge accurate ? Does the pressuretrol work ? Pigtail and path back into the boiler clear of any obstructions.

Your 5 PSIG is concerning. With your situation you may have an oversized boiler and/or other issues, my house heats fine at no more than 0.07 PSIG (2 inches of Water Column).

For best performance the boiler size should match the radiators' ability to dissipate the heat the boiler makes (the total of all of the radiators). The steam moves the heat. With the radiators they call it Equivalent Direct Radiation (EDR), with the boiler they call it 'Square Feet' on the rating plate, these two numbers should be close to each other. The EDR of each radiator can be calculated from charts of different radiator types then all the radiator's EDRs are added together.

A common situation is the boiler is oversized so the radiators can't dissipate all the heat the boiler is producing so the pressure rises, to me this is wasteful. The pressuretrol is suppose to shut off the burner when a certain pressure is reached, commonly 1.5 PSIG. Assuming the pressuretrol is set correctly and operating correctly it needs to be able to monitor the boiler's pressure, this is done through the pipes connecting it to the boiler. Very commonly the pipes (including the pigtail) between the boiler and the pressuretrol plug up with debris causing the pressuretrol to not be able to monitor the boiler's pressure. If you have an oversized boiler the pressure will keep building (until the thermostat is satisfied) since in this example the pressuretrol can't sense the boiler's pressure and shut off the burner.

A redundant pressure gauge like 0-5 PSI can be added as a second opinion of the system pressure and to verify the pressuretrol functionality.

Pipe pitch correct, can the system drain condensate back to the boiler properly. Any low spots that traps water. Incorrect piping that traps water.

Since you have odd noises and hammering and water coming out of the vents, besides possible excessive pressure issues there may be water (condensate) puddled in places where it should not be. So the steam pushes it along to places it should not be. In a steam system the pipes should be pitched so they drain correctly, minimizing the amount of condensate in a steam pipe. With age, renovations and other issues the pipe pitch may not be correct in various places trapping water where it should not be causing problems. The system's pipes should be visually inspected (possibly using a level if needed) for proper pitch.

Clean boiler water, skim to remove any oil.

The boiler works best with clean water that is not contaminated with rust or oil and other stuff. Draining the contaminated water can help remove the rust in the water however fresh water has oxygen so draining and refilling should be done as little as possible. Skimming is a process to remove oil contamination from the top of the water. Oil contamination will cause the boiler water to do strange things. Most boilers have a skim port which allows the oil to be drained away from the top surface of the water.

If you don't have the boiler's manual, with the make and model you probably can find one on the net and it should show where the skim port is.

most of the radiators in their pictures are sunrad type radiators. that is the shape the cast iron is cast in.

Sunrad or CastRay. Should be able to get sqft ratings from one of these: