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The boiler relief valve, what it does, why it leaks, and when to replace it.

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.

The boiler relief valve

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. ... Read More

The Second Reason a boiler relief valve leaks is:

Furnace expansion tank

The expansion tank on a boiler allows the water in the boiler to expand. Water can not be compressed and when it is heated it expands. the expansion tank has a diaphragm with 12 pounds of air pressure in it. This allows the the water a place to go when it is expanding. ... Read More

The third reason a boiler relief valve leaks is:

Furnace fill valve

The pressure reducing or fill valve for a boiler is set to only allow 12 psi in to the boiler. If this valve fails it will allow the pressure in the boiler to reach 30 psi or higher. ... Read More

The Fourth reason a boiler relief valve leaks is:

Some boilers have a hot water coil, sometimes called a tank less water heater. Some times a coil will develop a pin hole in it. If this happens it will cause the house pressure to seep into the boiler.

... Read More 

The Fifth reason a boiler relief valve leaks is:

Boiler Aquastat

The aquastat or aquastat relay, This is a very important part of your heating system. the item in the picture to the left is a secondary aquastat, it's purpose is to back up the main aquastat.

... Read More

The pressure should be. Click here to read more.

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