Boiler pressure out of control


  #1  
Old 12-07-17, 08:49 PM
A
Member
Thread Starter
Join Date: Dec 2017
Location: United States
Posts: 14
Received 0 Votes on 0 Posts
Boiler pressure out of control

we have a high pressure issue with my weil mclain CGA Gold gas fired home heat boiler. it, all of a sudden, started blowing out the pressure relief valve....at 2am. Later that am, i raced to the plumbing supply ended up replacing the amtrol ex30 expansion tank with a new one. and the watts B1156f pressure regulator. each newly acquired pressure related part resulted in the same outcome...gauge pressure would be 12-15psi at idle(i varied the pressure screw on the 1156). as soon as the system was activated by the thermostat, the pressure would increase and hover in the high 20s psi until it would burst out the pressure relief valve...a 30psi valve. several times i would close the main inlet line, relieve the pressure out of the relief valve, run the system and pressure would climb to the relief liimit and valve would blow out. same result when i didt it with the main line open. fyi, the relief valve was replaced last year.

im thinking the issue is within the boiler unit itself.

not sure what to check/replace next

any thoughts would be appreciated
 
  #2  
Old 12-07-17, 09:09 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 62,572
Received 1,599 Votes on 1,473 Posts
Welcome to the forums.
Thread moved to the boiler forum.

While this was over pressurized..... what was the boiler temperature ?

If the pressure doesn't rise when cold..... the water fill valve is not the problem.
No need to change the fill pressure.

I'm not the pro here but it sounds like an issue with the air pressure tank. Possibly there's a valve closed to that tank or a plugged small connecting nipple.

Pictures of your system will help us to spot problems and offer you better help.
How-to-insert-pictures
 
  #3  
Old 12-07-17, 10:27 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,495
Received 36 Votes on 28 Posts
Does this boiler also supply domestic hot water? If yes, does it have an internal "tankless coil" or an external tank heated by boiler water?

Pictures of the set up will help. Pictures need to be well lit and in focus. Close ups NOT needed at this time but pictures from far enough back to see how various parts are connected are often a big help.
 
  #4  
Old 12-08-17, 03:10 AM
A
Member
Thread Starter
Join Date: Dec 2017
Location: United States
Posts: 14
Received 0 Votes on 0 Posts
So this morning, after all the thermostats have been off all night, I turn on the system on to heat the house. Pressure at 10psi(plumber and I determine gauge is off 10 degrees because 30psi relief valve blows at 40psi) and water temp at 65 degrees. As soon as burners kick on the pressure starts to rise. Within seconds, before temp hits 90, the pressure is already at 25(35 on gauge) psi and relief valve is dripping. As temp continues to rise the relief valve starts to gurgle and eventually blows by the time the temp is 140 and I baby sit the system until the house is heated. Hope the pic helps. System was installed new in 2013.
 
Attached Images  
  #5  
Old 12-08-17, 03:46 AM
A
Member
Thread Starter
Join Date: Dec 2017
Location: United States
Posts: 14
Received 0 Votes on 0 Posts
here is a clearer pic

here is a clearer pic

here is a clearer pic
 
Attached Images  

Last edited by PJmax; 12-08-17 at 09:54 AM. Reason: expanded/enhanced picture
  #6  
Old 12-08-17, 07:05 AM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,495
Received 36 Votes on 28 Posts
Let me try this again. Pictures need to be well lit and in focus. Close ups NOT needed at this time but pictures from far enough back to see how various parts are connected are often a big help.
I'll add: More pictures and from different angles are better than a single picture.

First thing to do is to install a properly working gauge.

It reads as if you are starting at a real pressure of 20 psi and then it goes up some 10 psi from that point until it starts to lift the safety valve. It IS possible the safety valve is starting to lift at a lower pressure than it is set.

Otherwise, I would go out on a limb and state the expansion tank is too small.
 
  #7  
Old 12-08-17, 08:11 AM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 18,159
Received 69 Votes on 61 Posts
1 Did you check the psi in the exp tank before you installed it?
2. What type of heat emitters in the home? Cast iron radiators?
3. Although that unit does not have a tankless coil, do you have an indirect hot water heater?

I assume from what I read, you ruled out the fill valve buy turning off the feed valve after boiler psi was set to 12?
 
  #8  
Old 12-08-17, 10:54 AM
V
Member
Join Date: Jan 2010
Location: North East Kingdom of Vermont
Posts: 2,533
Received 1 Vote on 1 Post
Regardless of the focus, that still appears to be a very young boiler.

Is it possible that street pressure is entering the heating fluid through a leak in or near the heating coil and upsetting the pressure balance within the boiler ?
 
  #9  
Old 12-08-17, 11:16 AM
A
Member
Thread Starter
Join Date: Dec 2017
Location: United States
Posts: 14
Received 0 Votes on 0 Posts
installed a new amtrol ex30 and checked the pressure 2x
the boiler feeds 3 zones of baseboard heaters
no on the indirect water heater

im replacing the gauge and relief valve today.
 
  #10  
Old 12-08-17, 11:24 AM
A
Member
Thread Starter
Join Date: Dec 2017
Location: United States
Posts: 14
Received 0 Votes on 0 Posts
Originally Posted by Vermont View Post
Regardless of the focus, that still appears to be a very young boiler.

Is it possible that street pressure is entering the heating fluid through a leak in or near the heating coil and upsetting the pressure balance within the boiler ?
brand new install 11/13

I dont think so. i close of the main and maintain a 0psi
 
  #11  
Old 12-08-17, 11:35 AM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 18,159
Received 69 Votes on 61 Posts
You need to add air to the expansion tank when its under 0 pressure. Most likely removed from the system.. You cant check it on the system normally unless you drain off the psi of the boiler.. FYI...
 
  #12  
Old 12-08-17, 11:38 AM
A
Member
Thread Starter
Join Date: Dec 2017
Location: United States
Posts: 14
Received 0 Votes on 0 Posts
Originally Posted by lawrosa View Post
You need to add air to the expansion tank when its under 0 pressure. Most likely removed from the system.. You cant check it on the system normally unless you drain off the psi of the boiler.. FYI...
checked it before i installed it....12psi
 
  #13  
Old 12-08-17, 12:27 PM
S
Member
Join Date: Oct 2013
Location: United States
Posts: 3,246
Received 87 Votes on 81 Posts
By shutting off the feed line manually and getting the same result you have eliminated the feed valve.

Although the gauge may be off that is not causing your problem.

Since the relief valve only releases on high pressure and not constantly you can replace it but I don't think that will solve your problem. The current relief valve is doing its job.

You have no internal or external domestic water tanks or coil to leak into the boiler but even if you did that would maintain high boiler pressure if the boiler was hot or cold and the relief valve would be constantly leaking.

The boiler and tank have been working properly since 2013 so I wouldn't think the tank is too small or it would have leaked right off.

I know this is a new tank and you said you checked pressure before installing but everything I see points to the tank.

Since you're babysitting this thing anyway the next time your boiler is running just for grins tap your expansion tank, top and bottom.
Top should sound solid and the bottom where the bladder is should sound hollow or tinny.

If the whole tank sounds solid it is waterlogged and something has happened to your bladder and must be reinflated if possible or replaced if the bladder is ruptured.

If the tank is solid press in on the shredder valve and see if you get any water. If you do the bladder has ruptured and the tank must be replaced.

Hope this helps a little.
 
  #14  
Old 12-08-17, 02:43 PM
Z
Member
Join Date: Jan 2008
Location: Southeastern Pennsylvania
Posts: 3,363
Received 42 Votes on 41 Posts
Anything up with that air separator? Could a blockage have developed somehow? Donít know where crud would have come from all of a sudden though Ė just a WAG.
 
  #15  
Old 12-08-17, 03:20 PM
S
Member
Join Date: Oct 2013
Location: United States
Posts: 3,246
Received 87 Votes on 81 Posts
Z,
I wouldn't think so in this case.

He's getting heat so we know the water is flowing and although there could be some crap in the air vent it wouldn't effect the pressure, just maybe a little air in the system.

If you think about it, it would be the same as closing the cap on a leaky vent.

Just my thoughts. Good to hear from you. Have a good Christmas.
 
  #16  
Old 12-09-17, 05:42 AM
Z
Member
Join Date: Jan 2008
Location: Southeastern Pennsylvania
Posts: 3,363
Received 42 Votes on 41 Posts
Yep, that makes sense. And you have a good Christmas too spott.
 
  #17  
Old 12-09-17, 09:30 AM
A
Member
Thread Starter
Join Date: Dec 2017
Location: United States
Posts: 14
Received 0 Votes on 0 Posts
I still dont have my head wrapped around this one. so i replaced the gauge and the relief valve and all is working like a champ. pressure is steady at around 18psi when idle or running. One thing, after i replaced the expansion tank and the issue was still occurring, the intake side of the tank and pipe was cool to the touch. Now, as I expected, the top of the tank and pipe is very warm. i can only assume the relief valve, which i replaced last december, was blowing way before the rated 30psi not allowing the back pressure to fill the expansion tank. does that sound correct? do relief valve go bad that quickly? but the gauge reading really had me perplexed. are those things that flaky?
 
Attached Images   
  #18  
Old 12-09-17, 10:46 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 62,572
Received 1,599 Votes on 1,473 Posts
Pressure relief valves don't get flaky. They are extremely reliable.
When they go bad it's usually that they don't shut off all the way and drip.

All kinds of things can happen to a gauge.

For an easy quick reference tool..... get a test gauge.
They carry them in all the home improvement stores.

Name:  gauge.jpg
Views: 532
Size:  19.5 KB
 
  #19  
Old 12-10-17, 08:02 AM
Z
Member
Join Date: Jan 2008
Location: Southeastern Pennsylvania
Posts: 3,363
Received 42 Votes on 41 Posts
Wonder if the fix might have had more to do with draining and refilling the system in order to change the gauge and relief valve. Seems funny both the old gauge and old prv thought the pressure was high.

Is that a Check Valve after the tee on the pressure tank side of the tee? Is that supposed to be there? Maybe it’s not a check valve. Just wondering what that would be and why there would be a valve leading into the tank. I don’t remember ever seeing on installation diagrams a valve in that position other than an isolation valve – but I’m no expert and sure could be wrong.

(But could a sticky check valve explain things?)

Well second thoughts - I don't see how it could even work with a check valve - or could it? lol

Just a thought.
 

Last edited by zoesdad; 12-10-17 at 08:17 AM. Reason: 2nd thoughts
  #20  
Old 12-10-17, 02:12 PM
Z
Member
Join Date: Jan 2008
Location: Southeastern Pennsylvania
Posts: 3,363
Received 42 Votes on 41 Posts
OK Ė I think I see my error Ė thatís probably just an isolation valve with the handle out of view. LOL (canít stop laughing!!)
 
  #21  
Old 12-10-17, 04:14 PM
S
Member
Join Date: Oct 2013
Location: United States
Posts: 3,246
Received 87 Votes on 81 Posts
ZD,
These are just my thoughts on the situation. Going back to your original post #14 about the air separator blockage.

Something that wasn't mentioned until later was the pipe between the tank and the air scoop was cold after he changed the tank.

Then looking at that green isolation valve not going anywhere until you scroll down to previous pics. It's actually connected to the feed valve for the system and I think that other brass valve is actually another ball valve to isolate the tank.

My guess is that when they changed the tank initially and refilled the system through that line instead of air being released through the vent a lot of it went in the other direction and into the tank not allowing the heated expanded water to enter thus making the system act as there was no expansion tank at all.

Maybe there could have been some crud or something in the scoop preventing the air to bleed out unless the vent cap was closed and trapping the air in the tank and then when he drained the system again the air pocket was released.

The cold pipe was a dead giveaway there was no circulation into that tank due to air accumulation that could not be released from the vent in the scoop.

My suspicion is the gauge or the relief valve had nothing to do with the problem and would work if reinstalled, at least the relief valve. The defective gauge should have been changed just to operate properly but the relief valve was doing its job and was fine.

The air in the tank just had to be removed.

These are just my thoughts on what happened to see if it makes sense to you.
 
  #22  
Old 12-11-17, 06:20 AM
Z
Member
Join Date: Jan 2008
Location: Southeastern Pennsylvania
Posts: 3,363
Received 42 Votes on 41 Posts
spott-

You know orders of magnitude more about these systems than I do, but that sounds like a pretty good theory to me. These systems seem to get pretty complicated. I guess itís the fluid dynamics part of it.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: