I have a Hydro Therm gas fired hot water boiler. I assume it is from the year the house was built in 1963 as the sellers were not the original owners and they didn't know. Our PSI ranges from 10-20, sometimes it has gotten close to 30. A few weeks ago water came out of the release pipe but it has been three weeks. What is the normal PSI and Tempure on this boiler?

Normal pressure for a cold boiler is approx. 12 PSI. As the boiler heats it can often rise to 25 degrees. Check the pressure when it's cold. The fill valve should keep the boiler at 12 PSI. You also have an expansion tank which helps regulate the pressure, not unlike a well water system. Both the fill valve and the pressure tank, when beginning to fail can cause this issue. Although boilers can certainly last 45 years, not all of the parts do. A service call will certainly find the problem. But you may consider a new boiler since they are so much more efficienct than those of 45 years ago.

A rule of thumb is 1 lb. of pressure for each foot of height that the water must rise. Bleed the air out the system. Air can cause an unusal rise in pressure, otherwise, follow Missouri Bound's advise.