Boiler Pressure Relief Valve Now Leaking Continuously

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Old 02-12-15, 10:43 AM
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Boiler Pressure Relief Valve Now Leaking Continuously

Hello everyone!

After reading through a number of threads, I thought I might just post a quick message specific to my issue and see what some thoughts are.

ISSUE: Gas-fired boiler pressure relief valve has gone from low-volume, intermittent leaks (e.g. drips) that were relievable through some drainage (a few gallons) of the steel expansion tank to a higher-volume, continuous leak that only slightly improved with substantial drainage of the tank.

EQUIPMENT: Boiler is in a 101-year-old home. It is a WEIL-MCLAIN (the unit's manual is for Models CGM and P-CG Series 8) that uses a steel expansion tank suspended from the ceiling. I do not know the capacity of this tank, although I have included a photo for reference. The tank has never been warm or hot to the touch, on either the top or bottom, and has never drained anything but cold water.

BACKGROUND: Back in the winter of 2009, the same year the house was bought, I was out of town when my wife called saying water was coming from the pressure relief pipe. She called the plumber, and all she she saw him do was open the combination valve of the steel expansion tank and drain some water out. She was told to keep on eye on it and a bucket under the pressure relief valve. I also believe he stated the pressure was fine.

We had not had problems with it until last winter when it would intermittently leak. Sometimes this would be a hot, steamy leak coming from the pressure relief valve. Opening the expansion tank's combination valve and draining a few gallons of water would solve it each time. (Although there would still be a substantial SLOSH evident when the tank was given a little shake.) So winter turned to spring and spring turned to summer, and all was forgotten.

This winter, however, it started doing it again -- usually only after a precipitous drop in outside temperature. This morning, however, the basement floor was wet and draining the expansion tank was of little help.

PRESSURE/TEMP: The initial pressure check was around 7-8psi with a temperature of about 130F. After draining a substantial amount from the expansion tank, it did raise to 10psi with a temperature of 140F. After a couple hours it went to 12psi where it stayed for the most part (highest was around 15psi at one point after more draining).

OTHER:

The second floor bathroom cold water has lost pressure in the sink this morning as well.

After draining the expansion tank failed to stop the leak initially, I did depress the relief valve directly to get drainage. This actually caused the leak to increase flow for about 30 minutes -- until I drained more from the expansion tank. At that point, it slowed back down to what it was when discovered. At no time did the pressure dramatically change, however.

I had never turned off the SHUTOFF VALVE leading to the expansion tank when draining. However, after posting this I did try that (draining with the shutoff valve closed). This allowed the tank to be drained substantially... and slowed the leak to slow, continuous drips. I have not turned it back on yet to see what happens.

I was just wondering if anyone had any ideas as to whether this sounds like a pressure relief valve issue, a expansion tank issue, or something else. Any advice is appreciated. I am looking to see if this is something I can handle on a DIY basis or if I should make the phone call.


Thank you very much!

Bob


P.S. I apologize for some photos not uploading upright. In picture #6, the expansion tank is at the top of the photo, hanging.
 
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Last edited by Synapse; 02-12-15 at 11:08 AM.
  #2  
Old 02-12-15, 10:58 AM
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Bob,
Your expansion tank sounds like it's full.
You must fully drain the tank or it makes the problem worse.
Isolate the tank from the system.
Open drain on tank.
You have a red valve on the tank also. That let's air in the tank to eliminate a vacuum problem.
The main thing is, is to fully drain tank.
When done, open valve between boiler & tank and you'll hear water flowing back in to the tank and fresh water should feed back into the boiler and stop around 12-15psi.
Start boiler and test.

Shut the valve off before that red valve also to stop the water from feeding in as your draining.
When done open that valve to pressurize system again.
 
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Old 02-12-15, 01:33 PM
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Hi Spott,

Thank you very much for the reply!

I followed your instructions and was able to drain the expansion tank completely. I also turned the thermostat off and let the system cool down. It took quite a while to fully drain. It seemed to have air pockets of sorts clogging up the draining intermittently. But it eventually got all the air and water out of the tank. All that was left was a widely spaced single drip from the pressure relief valve.

When I turned the shutoff valve back on to allow the water to flow (making sure the other valve leading to the boiler was also opened), however, immediately the pressure relief valve started leaking again. The water completed its fill, the pressure raised to 15psi, but the dripping continues. There appeared to be no "sloshing" in the expansion tank.

Any further thoughts on where the problem could be emanating?

Bob
 
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Old 02-12-15, 02:23 PM
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Could be a faulty pressure gauge,

Read this:

http://www.doityourself.com/forum/bo...ure-gauge.html

Maybe the gauge says 15 but it's really 25?

It's also possible that the relief valve is opening at a lower pressure... if it's older than 5 years, just replace it as routine maintenance.
 
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Old 02-12-15, 02:39 PM
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Besides what trooper suggested, you can try after letting the boiler cool down, opening the relief valve to flush. Crap gets in sometimes and doesn't allow it to seal. When you close it tap the silver handle gently and if it will seat.
If not you will have to replace it. Now that everything is normal you may be better off anyway to start fresh.
 
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Old 02-12-15, 03:58 PM
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Thanks Spott and Trooper!

The relief valve is definitely over 5 years old. I will try to flush it once and make sure that there's no sediment issue... but I will indeed just replace it. With the system off and cool, water is just trickling out.

When replacing the relief valve... how much drainage do I need to do? Empty the tank and flush the boiler in its entirety by way of the relief valve release? Isolate the tank and just empty the boiler via the relief valve release? Or is there some other process I should employ beforehand?

I think I'll head over to the hardware store and pick up one tonight if I can.

Thank you!

Bob
 
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Old 02-12-15, 04:23 PM
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Bob, you always want to strive to drain as LITTLE WATER AS POSSIBLE from any system. There is never any good reason to drain and refill a boiler, it only creates more problems...

Even when servicing and you HAVE TO drain some water, the idea is to close as many valves as possible to minimize draining water.

FRESH water is loaded with dissolved AIR.

OLD water has had all the AIR driven out of it by the repeated heating.

When you introduce fresh water, you are introducing air.

Air in the system makes NOISES, but worse than that, it promotes CORROSION (rust) and mineral deposits to form inside the system.

You can't have rust without three things... FERROUS METALS, WATER, AIR.

Take away any one of the triad and there will be no rust.

We can't see what valves you have on your system... pics are too small... and I'm sure don't show everything...

BUT, in general to change a relief valve you need to AT LEAST 'de-pressurize' the system. You certainly don't want water gushing out at 15 PSI!

Experienced plumbers sometimes only depressurize the system, have the new valve in hand with dope on the threads ready to reinstall, loosen the old one... and QUICKLY! replace with the new.

You might not want to do this though.

So, if you can isolate all the system piping from the boiler by closing valves to keep the water in the pipes from flowing back to the boiler, you only need to drain the boiler water below the point that the relief valve is connected.
 
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Old 02-12-15, 05:17 PM
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Bob,
No need to drain the tank. Shut your boiler feed, your valve between the tank and the boiler, any valves on your supply and return pipes. If you can isolate the boiler, you can drain through the relief valve.
As trooper said prepare the new one and when water stops swap out quickly.
Loose up your drain line off the relief valve so you can take it off quickly.
Once water stops, remove pipe then unwind old relief leaving a few threads. Before removing, lift lever again so you don't get surprised. If nothing comes out change quickly in case something is leaking by.
Once new is on and tightened you can open your boiler feed valve and expansion tank valve.
If you did isolate the boiler don't open the supply and return until after you have pressurized the boiler.
When you open feed valve, open relief valve and you will get the lions share of air out.
Close relief valve when water starts coming out, open system valves and test.
 
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Old 02-13-15, 06:49 AM
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Thank you both Spott and Trooper for the invaluable assistance yesterday!

I can report that the problem has been fixed. I installed a new pressure relief valve, as generously instructed, and the leaking has completely stopped. I will be sure to replace it as part of routine maintenance in the future!

I did notice that the cooled, rested pressure is reading about 16-17psi this morning (I shut the thermostat off around 3a). I got up in the middle of the night to check things out, as the house seemed hotter for some reason, despite the thermostat not having been changed (my HOLD temp had been reset, unbeknownst to me, after I turned the thermostat off). While the boiler was firing, the pressure was maybe 24psi. I didn't know if I should attempt to bring this down some.

There are three crank valves that I shut down last night before installing the relief valve (in ADDITION to the valves leading into and out of the expansion tank) -- valves that I had never messed with before. One was attached to the pipe that has the motor pump attached. The other two were related to pipes that led into the boiler. Would the proper adjustment of any one, or combination, of these valves be appropriate for purposes of lowering the pressure?

Lastly, can anyone think of ANY reason why the second story bathroom's sink has NO PRESSURE coincident with all this?

I took some photos to illustrate. I apologize for the poor lighting and rotated uploads.

Again, thank you very much for all your assistance!

Bob
 
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Last edited by Synapse; 02-13-15 at 08:37 AM.
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Old 02-13-15, 08:49 AM
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Pics are still a bit too dark and too close to figure anything out from them... but not sure we need any more pics at this point.

the pressure was maybe 24psi. I didn't know if I should attempt to bring this down some.
You still have no idea if the pressure gauge is accurate. In order to proceed with this line you would need to know that. You should not adjust anything without accurate data...

Would the proper adjustment of any one, or combination, of these valves be appropriate for purposes of lowering the pressure?
No, that would not be the proper way of adjusting the pressure.

The MINIMUM COLD BOILER pressure is set by your 'pressure reducing valve', and the pressure increase when the boiler is heated is controlled by the expansion tank.

You need to know what the REAL pressure is before you do anything.

Lastly, can anyone think of ANY reason why the second story bathroom's sink has NO PRESSURE coincident with all this?
Domestic water pressure should have nothing to do with boiler pressure. They are two totally isolated systems. It seems like it's conincidence that it's coincidental...

Both hot and cold have no pressure?

Did you close a valve that was associated with the domestic plumbing and forget to open it again?
 
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Old 02-13-15, 10:37 AM
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OK, I will ask the question...Did you replace the relief valve with one for a boiler and not a water heater. The set points are different on them and I know in my area the boiler relief valves are not available in big box stores.. I am not doubting your abilities but, just want to make sure this was done correctly.
 
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Old 02-13-15, 11:38 AM
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Bob,
The shutoff valve coming off the top of the boiler is your supply shutoff valve.(valve on right), that shuts the water off going to the heat emitters. I'm guessing radiators.
The valve on the left above your red b&g pump is your return shutoff valve.
I can't tell about the one in the middle. It looks as though it comes off the supply pipe possibly from a tee fitting and goes back towards the boiler.
It's too dark to tell. Can you get a better pic of the middle pipe. Higher and lower and the fitting behind the return pipe, that's the pipe where the thermostat is.
I would like to see that whole middle pipe. It could possibly be a bypass pipe so you don't shock the boiler.
You have a high water content system with a low water content boiler.
You have a bell shaped gold colored valve up by your red valve on your expansion tank. That is your pressure reducing valve and where the pressure would be adjusted if need be but don't concern yourself with that for now. That was just for information purposes.
The bottom line is all the valves that are visible should be open when running the boiler, until the middle pipe can be better identified.
 
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Old 02-13-15, 12:11 PM
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I'd like to add a 'tidbit' about the pressure reducing valve adjustment...

These valves don't just 'go out of adjustement'. When they fail it's almost always that they either leak through internally, or get plugged internally.

Attempting adjustment for a supposed pressure problem is never recommended, at least by me... others may have different opinions, but if a pressure reducing valve DOES 'drift' out of calibration, then there's something seriously wrong with it and it should simply be replaced.

The chances are MUCH MUCH higher that your BOILER GAUGE is out of calibration. This is VERY common. The gauges that are installed on boilers are JUNK!

Before you do anything else, VERIFY YOUR GAUGE!
 
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Old 02-13-15, 02:03 PM
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I completely agree with this post by Trooper.
 
 

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