During my inspection on Sunday I noted that the boiler was leaking, and upon further investigation found that the pressure relief valve was leaking. I took one picture of the valve and wanted to get a better picture, just as I clicked the picture and the valve went off like old faithful. Scared the crap out of me!!
This is a good reason to recommend that there be a Pressure relief valve drain line on the boiler.
The boiler was short cycling and steam could be seen coming from the valve also.