The boiler relief valve or the blow off valve is a safety valve that protects your heating system from building up too much pressure and possibly blowing up. It's a very important part of your heating system.
Some times the relief valve or blow off valve will leak, and naturally people assume that it is because the relief valve is defective. Sometimes this is true, and if it is leaking you should replace it even though it is leaking for other reasons. But it may just be doing it's job.There are 5 reasons a relief valve leaks.
The first reason a boiler relief valve leaks is:
Nothing lasts for ever, and a relief valves or blow off valve will go bad.
A boiler relief valve needs to be tested every three months to be sure it is operating properly.
If you have not checked yours out for a long time, you should have it checked out ASAP.