Expansion tank Schrader fitting rusted almost shut?

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brasseng

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Starting a few months ago my 40 gallon domestic tank relief valve leaks once in a while to relieve pressure. Today I tried to check the pressure in the expansion tank, and read no pressure. I tried to add pressure to the expansion tank after shutting off the water and opening a faucet, but it was almost impossible. I could add a small amount at a time using my compressor. Compressor gauge would spike up and then over a few minutes slowly fall. It appears that I was successful adding pressure because a few hours later there was a lot more water on the floor. But I also cannot relieve pressure when I push in the needle on the Schrader valve. It’s almost like the Schrader valve has rusted almost totally shut inside the tank. The needle does move when I push it. Seems like I may need another tank if that’s what is happening. Thanks for any thoughts you may have.
 

Jadnashua

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REplace the tank. There should never be water or rust...sounds like the bladder is shot which is why it rusted and the T&P valve is opening. Note, it's not a bad idea to replace the T&P valve once it has been opened. It might be fine, but watch it and be prepared to replace it. Mineral deposits and corrosion over time can prevent it from resealing all of the time.
 
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brasseng

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I replaced the tank and the problem was solved. I removed the schrader valve from the old tank and tried to insert a rod through the opening. I couldn't insert it very far, it felt like the bladder was stuck against the shell of the tank. I decided to cut the tank apart. There was definitely enough rust for the bladder to stick to the shell. Attached is a picture. Thanks guys for your help.
 

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brasseng

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The shrader valve didn't look rusty when I removed it. My guess is that the air wouldn't go in only because the rubber was adhered to the shell. I should have tried reinserting the shrader valve after I pulled apart the tank to verify.
 

Jadnashua

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The seal on the Schrader valve is rarely perfect. A rubber seal in the cap, when present, can act like a backup, and keep air in there for a long time. But, once the air does leak out, the bladder will be pressed against the metal, and if there was rust, it also had to be leaking...iron doesn't rust without some moisture to aid it along in that sort of thing.

The key to this is preventive maintenance. Few people do it, and it is a tribute to the engineering that these things last as long as they do after being ignored, but like most tools, they'll last longer if you do some PM on them.
 

Gary Swart

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I would wonder where the rust is coming from. Do you have galvanized plumbing? Copper, PEX, and CPVC do not rust. Was the inside of the tank rusted?
 

FullySprinklered

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I replaced the tank and the problem was solved. I removed the schrader valve from the old tank and tried to insert a rod through the opening. I couldn't insert it very far, it felt like the bladder was stuck against the shell of the tank. I decided to cut the tank apart. There was definitely enough rust for the bladder to stick to the shell. Attached is a picture. Thanks guys for your help.

Nice cut. What did you use?
 
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