Incorrect Pressure gauge on Burnham boiler

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Old 10-12-06, 07:22 AM
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Incorrect Pressure gauge on Burnham boiler

I have a Burnham Series 2 gas fired boiler (25 years old) and I believe the pressure/temperature gauge is reading incorrectly. With no pressure (boiler drained) the gauge shows 10~15psi.

How easy is this to replace? The metal housing around the boiler appears to be in the way. Hopefully I don't have to remove the housing.

What prompted this is a continual draining of water through the safety valve when the boiler is running. I discovered recently that my two year old Amtrol expansion tank had a leaking diaphragm (lost the air cushion in the system) so I replaced it. But I still get water through the valve. I suspect the cold pressure is much higher than 12 psi because of a defective pressure reducing valve but I cannot determine that due to a suspect gauge. Is there any way to determine the pressure in the boiler by other means than the gauge on it?
 
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Old 10-12-06, 05:24 PM
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Boiler pressure

Where the relief valve screws on you could put a tee & a pressure gauge off the branch of the tee. As a one time check, you could use a tire gauge on the tank. The tank pressure will be the greater of either the air charge in the tank (usually 12#) or the boiler pressure. Relief valves often need to be replaced after opening a number of times due to a bad tank. An easy way to check the reducing valve is to pressurize the system to 20# on your existing gauge then turn the water off to the reducing valve. If the pressure does not go up, it is almost certain the reducing valve is bad.
 
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Old 10-13-06, 07:28 AM
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Originally Posted by Grady
An easy way to check the reducing valve is to pressurize the system to 20# on your existing gauge then turn the water off to the reducing valve. If the pressure does not go up, it is almost certain the reducing valve is bad.
I'm sure you are right but I don't understand the mechanics of this procedure. Why should the pressure in the system go UP when the water is turned off to the reducing valve? Are you referring to the pressure in the house/pipe (40~60psi) or in the boiler?
 
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Old 10-13-06, 06:56 PM
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Pressure

Exactly. The pressure should not go up with the valve to the reducing valve closed.
If the pressure steadily increases with said valve open, but not when it is closed, it tells you the reducing valve is not ceasing to feed water once the boiler reaches the set point of the reducing valve.
The reducing valve should only feed water when the boiler pressure is BELOW that of the set point on the reducing valve. Most reducing valves are factory set at 12 psig.
Hope this helps to clear things up.
 
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