Boiler press relief valve leak

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Old 02-23-11, 10:29 AM
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Boiler press relief valve leak

Valve relieving, a quart an hour, when boiler running. Pressure is 12 psi sitting, 31 running. Relief valve 30 psi

Problem checking expansion tank pressure. Got no reading on tank. Drained sys to 0 psi, and get no reading on tank. If I try to fill it with bike pump, it is very hard to pump, but when I pull the pump, puff when air escapes, then reads 0 on tire gauge. Opened tank drain, water escaped, then drained system to 0 again and got no water, air escaped. Reset system, 12 psi again, nothing in expansion tank.

Even if expansion tank is shot, where's the 12 system psi? The tank is mounted nipple up, so even without a diaphragm, nowhere for air to escape. Any ideas?
 
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Old 02-23-11, 10:37 AM
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also,hear water sloshing in expansion tank, when sys is reset at 12 psi.
 
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Old 02-23-11, 10:39 AM
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The air goes into your boiler piping. Your tank is shot and needs to be replaced.
 
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Old 02-23-11, 02:39 PM
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Opened tank drain, water escaped,
What 'tank drain' are you referring to?

The tank is mounted nipple up
You mean the air valve is on top?

I kinda agree that it sounds as if there's a problem with the tank and it needs replaced, but I don't quite understand what all you are talking about...

Can you take a few pictures so we can see what yer working on?

Free account / Image hosting, free photo sharing & video sharing at Photobucket / upload pics there and come back here and drop a link to your PUBLIC album.
 
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Old 02-23-11, 03:33 PM
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i also want to add that the expansion tank does not provide pressure for the system. It is there to provide a place for the water to expand into when it gets heated up. You put 12 psi of pressure on the air side of the expansion tank to make it equal with the water pressure on the water side. That reduces the strain put on the bladder inside the tank. Under normal conditions with both sides of the bladder set at 12 psi, the bladder will only experience a pressure differential of 5 psi when the boiler water is hot. If there was 0 psi on the air aid, the bladder will experience 17 psi of pressure. That will make it stretch a lot more and reduce its lifespan.
 
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Old 02-23-11, 08:17 PM
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The tank is attached to the system as follows: from a tee between the cold water feed, and an american air purger, follows a horizontal line through an inline shutoff valve, elbows to vertical, through a cut-off valve then into tank. Air valve is thus on top of the tank. In the cut-off valve threaded into the bottom of the tank is a little thumbscrew. It releases air and or water from the water side of the tank. That's how I drained it.

Thanks for the help, here's a link to photos

https://picasaweb.google.com/tweed75...eat=directlink
 
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Old 02-23-11, 08:22 PM
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I'd come to the same conclusion on the tank, but still curious about the air. In this config, it's like a diving bell (I'm a Navy guy) So with water below, and a solid tank above, how does air escape? Seems like it'd just be trapped above the water.
Not to overthink it or anything....
thanks
 
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Old 02-23-11, 09:28 PM
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That bleeder in the side of the valve under the expansion tank could be tank side or boiler side.

You are going to get water out of it.

You shut the red handle valve to the expansion tank you will have 12psi in that short length of pipe to the expansion tank. So you bleed off the pressure and residual water so you dont have a flood.

Now before you do anything... the air valve at the top of the tank where you are testing the pressure....try to relieve some air out of it like you would a tire. What comes out????

If water change the tank.

If nothing then you should be able to pump it up.

Possibly the shrader valve it defective or you did not put the pump on far enough.

Here is some info on expansion tanks.

http://s3.pexsupply.com/manuals/1260..._PROD_FILE.pdf

Let us know
 
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Old 02-24-11, 04:52 AM
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ok, that's the big mystery. System running right now, press on valve stem, NOTHING. No air no water, no sound. The valve stem depresses fine. Open thumb screw on bleeder in side of valve and water and air spray out.
 
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Old 02-24-11, 04:57 AM
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Try to "inflate" tank with a tire chuck and 20 psi, still get nothing after I pull it off.
 
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Old 02-24-11, 06:10 AM
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Originally Posted by ted757 View Post
I'd come to the same conclusion on the tank, but still curious about the air. In this config, it's like a diving bell (I'm a Navy guy) So with water below, and a solid tank above, how does air escape? Seems like it'd just be trapped above the water.
Not to overthink it or anything....
thanks
Ok. I understand your question now. Yeah, your tank is not mounted properly. I'm not sure how much that will affect your performance as far as the tank is concerned. It the air on the water side probably will never get out.
 
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Old 02-24-11, 06:38 AM
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Anyway, just replaced the tank, old one full of water, now we wait.

Thanks for all the help.

T
 
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Old 02-24-11, 06:41 AM
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So far so good, and Amtrol guy said the tank works in any orientation, it's worked for 7 years and the one on the old boiler was mounted the same. So looks like the tank failed, and the weight of the water created the lack of pressure reading. That's my guess and I'm sticking to it!
 
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Old 02-24-11, 06:52 AM
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I hope you changed that air vent on top of the air seperator. It looked pretty cruddy. Probably not working.


Mike NJ
 
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Old 02-24-11, 04:24 PM
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Amtrol guy said the tank works in any orientation, it's worked for 7 years and the one on the old boiler was mounted the same.
While it is true that the tank will work in any orientation, the fact is that there is a correct, and an incorrect way of installing them. It's not about whether it will 'work' or not, it's about the longevity of the tank itself. When air can be trapped in the tank it introduces a water/air interface point. That interface point can, and will ultimately rust the tank from the inside. It could take a few years. If you don't mind replacing the tank every 7 years, then by all means, leave it the way it is. Oh, and never check the air charge in the tank either... that will assure that the tank fails prematurely.

See:
http://www.amtrol.com/media/document...0EXTROL_IO.pdf

and note the notes... particularly #3

Also see:
http://www.amtrol.com/media/document...rochurelow.pdf

and note that every diagram shows the tank mounted with the water up, and air down. There's a nice explanation of how the tank works on page 2 of this brochure.

A tank that is properly installed and maintained can last a LONG time... 20 years or more. I have proof of this in my own mechanical room.

The reason that you could not get any air into your tank is because it was full of water. You can not compress water. IF that little bleeder cap is on the TANK SIDE of that valve (I think it is), then after closing the main valve you should have left that cap loose. As you added air to the tank, it would have forced the water in the tank out and allowed you to add air to the tank.

Now that you have the new tank installed, do yourself a favor and CHECK THE AIR CHARGE at LEAST every two years. Do this by closing that stop valve below the tank, opening the cap to bleed any pressure from the tank, LEAVE THE CAP OPEN... check the air charge and add air to 12 PSI as needed. Close the drain cap, open the stop valve.

The ONLY way that you can accurately check the pressure of the air charge is by having the water side at ZERO PSI... atmospheric... if there is ANY pressure on the water side of the rubber bladder inside the tank, you will NOT get an accurate air charge or reading on the air side.
 
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Old 02-26-11, 08:48 PM
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Actually working well, but I did clean it out to make sure, thanks.
 
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Old 02-26-11, 09:03 PM
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That orientation makes sense, and I'm going to spin it over if it's not too much trouble in the tight space. My old tank was in the same orientation, though, and it lasted as long as the first boiler; over 24 years.
Thanks for the advice on air charge. I actually tried to pressurize the tank with the system drained to 0 psi. But what I found out after removing the old tank is it doesn't like to drain by just gravity. I left it upside down in the driveway, and still had to agitate it to empty it!
That bleeder cap is actually on the feed side of the valve, probably should have been installed the other way, huh? This install was done by a very strong local company, by the way, but ready for the killer? I bought oil tank autofill for 5 years to get $500 off, and got a GUARANTEED OIL PRICE OF $1.10 A GALLON FOR THAT 5 YEARS! Unfortunately, it lapsed last year, but what a payday that turned out to be!
 
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Old 02-26-11, 09:52 PM
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a GUARANTEED OIL PRICE OF $1.10 A GALLON FOR THAT 5 YEARS!

They usually reset the prices and find it hard to believe... Good for you if its true....


Mike NJ
 
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