Need to replace expansion tank

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Old 12-02-13, 12:15 PM
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Need to replace expansion tank

I need to replace the expansion tank on my system. I have a cutoff valve on the expansion tank.

Is replacing the expansion tank as simple as shutting the valve off, unscrew the expansion tank and putting the new expansion tank on?

I have done a bit of research and read that I need to drain the boiler to bring it down to a suitable pressure and then replace the tank. Is this necessary?
 
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Old 12-02-13, 01:08 PM
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Hi. Not if you have a valve there... Thats what makes it easy and no need to drain the system..

Just be sure to check the psi in the new tank before you install... Should be 12 psi....

How do you know your old tank is bad? Did you try adding air to it?
 
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Old 12-02-13, 01:36 PM
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Actually... I would recommend draining the boiler to zero and then closing the valve between the system and the tank, and THEN removing the tank.

If you simply close the valve first and then remove the tank, any water and pressure that is in the tank and pipe at the time you close the valve will spray out when you remove the tank.

It may not be much, or it could be a bit... depending on the condition of the tank and how much water is in it.

IF you have the shutoff valve on the line, AND a DRAIN VALVE between the tank and the shutoff, you don't have to drain the boiler. Close the shutoff, open the drain into a bucket to relieve pressure from the pipe and tank, and remove tank.
 
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Old 12-02-13, 01:42 PM
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Numerous people have told me that the expansion tank is done because when you tap on it it sounds like its completely filled with water. Also I have a valve that continues to drip water (into a bucket). My buddy that is a plumber said the valve is a failsafe if the expansion tank goes and the reason why it keeps dripping water is because the expansion tank is shot.
 
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Old 12-02-13, 03:40 PM
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Numerous people have told me that the expansion tank is done because when you tap on it it sounds like its completely filled with water.
Professionals these numerous people?

I personally have no faith in the 'tap test'. One would have to know what an empty tank sounds like as opposed to a full one. How can one tap on a tank with no other reference and say... oh, it's shot, it's full of water.

Also I have a valve that continues to drip water...a plumber said the valve is a failsafe
I have to presume you are talking about the SAFETY RELIEF VALVE, and yes, it will drip water when the pressure approaches 30 PSI in the system.

So the next question becomes, what IS the pressure in the system?

Thing is, the tank might not be 'bad', it might just need an air charge.

Show us some pictures.
 
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Old 12-02-13, 06:21 PM
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Yes all professionals who have told me the tank was bad. A total of 3 people, and I didn't even ask them about it.

I ended up going out and picked up a new expansion tank. I shut the valve off and replaced it. The old tank was completely filled (I was able to almost fill a 5 gallon bucket). The tank is 4.4 gallons.

I will get a reading on the pressure of the boiler tomorrow and let you know!
 
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Old 12-03-13, 10:28 AM
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Yes all professionals who have told me the tank was bad. A total of 3 people, and I didn't even ask them about it
Were they looking for work? What did they do, knock on your door and ask if they could tap your tank? How much did they want to replace it?

Mind you, I never said that the tank was NOT bad... just disagreeing with the 'tap test method'.

Now that you've replaced it, how's it working?
 
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