Expansion tank and H2O Regulator adjustment?

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Old 01-23-08, 10:05 AM
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Expansion tank and H2O Regulator adjustment?

OK Did lots of searches. My whole system is only 3 years old!
1 pressure relief was relieving water on a daily basis.
quart or so
2 figured out expansion tank (newer model with air gauge) was full
3 just lowered temp and psi and emptied tank, replacing it (the same one) with 10-12 psi (bike pump) Not sure if air was getting in?

Questions
A what caused exp. tank to fill up?
B how do I know if my exp tank is faulty/defective or not?
C I played around with water pressure regulator valve (beforehand) so what is the best way to recalibrate it?

Tank filled up imeddiatly,could this been because I may not have the correct air pressure in the tank? how much water is suppose to be in these tanks?
Problem now it's leaking continuously at much under 30psi more @20 psi
Totally baffled
Well its looking like I most definatly have a busted expansion tank!
thanks
New advise I was told to shut off H2O feed valve to main boiler and that should take care of problem.
 

Last edited by biketrax; 01-23-08 at 11:06 AM. Reason: update
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Old 01-23-08, 10:10 AM
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Bladders can rupture. Replace it with the same size or larger model. If you can put more distance between it and where it connects you can minimize the thermal expansion cycling which has to be a factor in these wearing out.

If it's smaller than an ET-30, then I'd go ET-30 sized for sure.
 
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Old 01-23-08, 02:25 PM
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The bladder is busted if you get water out of the valve on the bottom of the tank. Just press the stem slightly. If you get air bladder is OK. If you get water bladder in ruptured and tank needs replaced. Sizing is something to look at as Who stated. What size boiler and what type radiation?
 
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Old 01-25-08, 02:43 PM
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Alright exp tank seems OK.

NO water coming from bottom of exp tank!
So now I have emptied the exp. tank, filled the base with about 15# of air and replaced and seems to work better (less overflow) but still losing some water. So I believe my problem lies in the regulator or overflow valve. I think it may be theregulator since it seems that the water seems to be overlowing over the 30# mark.

In regard to previous questions: This is a 4 section oil burner and I have convectors (toe kick/spave heaters and adding some base board currently )

Question could this be resulting from air in the system?
In other words do I need to purge my heaters upstairs after this happens??
thanks
 
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Old 01-25-08, 03:40 PM
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Let's make sure we're all on the same page...

bike, when you charge the expansion tank with air, you need to have ZERO pressure on the water side, i.e. in the boiler system. If you don't have zero on the water side, you will not get accurate reading on the air side.

[late edit: I just re-read your original post and see that you said you did drop the PSI when you charged the tank, but I'm gonna leave the rest of my reply here for the sake of completeness]

The best way to do this is to CLOSE the manual water fill valve. Connect a hose, or use a bucket to drain just enough water from the boiler to drop the pressure to zero.

Only then will you get an accurate charge on the tank.

After you are certain that you have a proper charge on the tank, open the manual fill valve and let the system re-pressurize until you have 12-15 PSI when the system is COLD (at least under 100F anyway), and CLOSE the manual fill valve again.

Run the boiler up to temperature and watch the pressure.

Does it increase say 5 - 8 PSI ? (less is better, could be as high as 10 perhaps). Does the pressure stay in this range with the manual fill valve closed ?

OK, now, open the manual fill valve. Watch the pressure. Does it now start to increase ? If so, then it is a good bet that your "pressure reducing valve" is defective.

The advice to leave the manual fill valve closed to 'take care of the problem' is a BAND-AID at best, but you can run the boiler this way until you have a chance to change the valve. KEEP AN EYE ON THE PRESSURE IF YOU DO !

To re-adjust the pressure reducing valve, you need to back the screw out counter-clockwise until you are pretty sure it's further out than it was when you started messing with it.

Drain some pressure from the boiler as above ... leave about 5 PSI on the gauge. Open the manual fill valve and watch the pressure. If it stays at 5 , then 1/4 turn at a time, start screwing the screw on the reducing valve back in. Wait a few minutes between each adjustment. At some point, you will see the pressure start to climb up. Keep going 1/4 turn at a time until you are at 12 PSI. Be sure to wait several minutes between each adjustment, because these things are slow to react. When you think you have it adjusted properly, snug the locknut.

It's possible that the pressure RELIEF valve is now leaking a bit because there may be some debris from the boiler under the valve seat. If it is consistently opening at 20 PSI, you may have to also replace the relief valve, OR you may have a defective pressure gauge on the boiler.

NO, air in the system will not cause over pressure. It will in fact LESSEN the problem to some small extent, because air can be compressed, while water can not. That's the theory behind the expansion tank. The air in the tank is a 'cushion' for the expanding water to push against.
 
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Old 01-25-08, 03:53 PM
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What could cause the tank to lose it's air charge and fill with water ?

Most commonly would be a leaking schrader (tire) valve. After you are sure it's pressureized properly, put some spit or soapy water on the valve. Look for bubbles. If you see them, you can go to the auto store and pick up a new valve and a tool to change it.

Tanks will lose 1-2 PSI of air yearly ... the air will permeate through the membrane, into the system. They should be checked occasionally for this reason.
 
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Old 01-25-08, 07:49 PM
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thanks trooper!

Will do things in an orderly fashion as you described.
Makes sense in your sequence. I am begining to
understand.
thats a real good point on the debris (perhaps) in the pressure relief!
thanks!
 
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