Boiler Pressure Too High

Reply

  #1  
Old 10-19-05, 05:15 PM
Member
Thread Starter
Join Date: Feb 2005
Posts: 36
Upvotes: 0
Received 0 Votes on 0 Posts
Boiler Pressure Too High

Hello,

Towards the end of last year's heating season my boiler started acting up. I had a total loss of pressure in the boiler. The plumber came out and replaced the pressure reducer valve and relief valve. The system worked fine, but a couple of days later I noticed that the boiler pressure would reach 30 psi and the relief valve would open. I have blead all the baseboard units at least 4 times to make sure all the air is out of the system, but the pressure still reaches 30 psi. Can anyone point me in the direction of what is the cause of this? I have a 40 yr old American Standard gas boiler. The expansion tank has water in - don't know how much and I don't see any type of leaks anywhere.

Also, I'm looking at replacing my 40 yr. old American Standard gas fired boiler with a new one this year. Current system says that the BTU input is 120,000 and Output is 96,000. I never had a problem with the house not being warm enough, but I have read the threads that highly recommend a Manual J heat loss test be accomplished before purchasing a new unit. I did have one plumber show yesterday and he recommends a Weil-Mclain, 80+, sealed combustion system. He said since the boiler sits in the same part of the basement were the washing machine is located, he recommends the sealed combustion boiler because the chlorine/bleach will oxidize the burners on an open system. Can anyone recommend some good boiler brands? I'm a little shocked that he didn't say anything about the Man J heat loss test. He just measured all the baseboard units in the house. For the Weil-Mclain unit (doesn't say what model), 1 new expansion tank, 1 air purger, 3 bleed ports and 1 low water cutoff switch total costs is $5,800 - is this good or bad?
 
Sponsored Links
  #2  
Old 10-19-05, 11:01 PM
Member
Join Date: Jul 2005
Location: SE Wisconsin
Posts: 30
Upvotes: 0
Received 0 Votes on 0 Posts
Sounds like a leaky pressure reducer. This will continue to slowly let water into the boiler. On my system, I do have a pressure reducer that I use when I have to fill and bleed the radiators, but once it's filled, I shut off the supply. In order to protect the boiler in case of a leak, make sure to have a low water cutoff.

Michael
 
  #3  
Old 10-20-05, 05:27 PM
Member
Thread Starter
Join Date: Feb 2005
Posts: 36
Upvotes: 0
Received 0 Votes on 0 Posts
If the reducer valve was bad wouldn't the system go to 30 psi just sitting there? It never does - stays at 12 psi. But after the boiler has been in use for about a day the pressure builds to 30 psi and then pops the relief valve. Can you test a valve to see if it is bad while in-line or do you actual have to remove it and then test it? The reducer valve was installed towards the end of last year. Thanks for any help.
 
  #4  
Old 10-20-05, 05:46 PM
Grady's Avatar
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 13,928
Upvotes: 0
Received 0 Votes on 0 Posts
High Pressure

I think you have a waterlogged expansion tank. If it is conventional tank with a drain, you need to drain it completely. If it's a bladder type tank with an air valve on one end, the bladder is likely bad which means tank replacement.
 
  #5  
Old 10-21-05, 04:03 AM
Member
Thread Starter
Join Date: Feb 2005
Posts: 36
Upvotes: 0
Received 0 Votes on 0 Posts
It is an old style expansion tank - no bladder. Underneath there are two valves. Looks like one drains the tank and the other is to let water into the tank. Also, there is a bleeder vavle located on the bottom of the two valves. Do I need to drain all the water from the whole system or can I just drain it from the tank? Once I turn the water back on, will the tank automatically fill to the correct level? Thanks for any help.
 
  #6  
Old 10-21-05, 07:58 PM
Member
Join Date: Nov 2002
Location: Massachusetts
Posts: 1,816
Upvotes: 0
Received 0 Votes on 0 Posts
Whoa! Nellie!

The one common thin seen for this is that the tankless or its associated circuit is leaking into the boiler water, The DHW line pressure is higher than 30 PSI and pressure goes from higher to lower ALWAYS.
Its either the tankless or indirect hot water line is leaking water into the boiler water circuit.....That was an easy one!
 
  #7  
Old 10-22-05, 06:28 PM
Grady's Avatar
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 13,928
Upvotes: 0
Received 0 Votes on 0 Posts
Rcjb

To drain the tank shut off the valve between the boiler & the tank then open the drain valve (the one with garden hose threads). Be sure to drain the tank completely. Don't be fooled into thinking the tank is empty just because water stops flowing out the hose you need to attach. Many drain valves have a screw in the side of the fitting into which the valve screws. The purpose of this screw is to allow air into the tank while draining. In order to drain the tank completely, air has to get in to replace the water coming out. Removal of this screw will allow air into the tank.
 
  #8  
Old 10-22-05, 06:53 PM
Member
Join Date: Nov 2002
Location: Massachusetts
Posts: 1,816
Upvotes: 0
Received 0 Votes on 0 Posts
tank expansion

OK you have a conventional expansion tank. Valve off the tank before and after and make sure the make up water supply is off. Drain the tank completely. as stated the small square slotted screw needs to be opened to let air into the tank. When drained , keep the tank valved off, close the air vent you opened earlier, and open the makeup water supply for ten minutes and read the pressure reading on the boiler (all the time this boiler switch is off) unless there is no way to isolate the tank from the boiler. If you can, it should read 12PSI this lets you know the regulator is working properly. Open the isolation valves you closed earlier to the operating position. The gauge glass should read 1/2 to 3/4 full. Turn on the boiler. The makeup water supply stays on all the time by the way!
 
  #9  
Old 10-25-05, 06:19 PM
Member
Thread Starter
Join Date: Feb 2005
Posts: 36
Upvotes: 0
Received 0 Votes on 0 Posts
Grady and Others, thanks for the information. For the past three days now the boiler is operating perfectly. I drained the expansion tank completely, along with the whole system. I didn't see any screws attached to the drain valve of the expansion tank, just a bleeder valve. However, there is a square looking screw attached to the bottom of the expansion tank - looks more like a plug that you would remove if you had to drain the tank in a hurry. Also, there is no type of window or gauge on the expansion tank itself. I refilled the system according to your instructions and blead the system as you described and everything is working correctly. The pressure gauge reads 12 -13 psi cold and goes up to 15 psi when at 190*F. Thanks again.
 
  #10  
Old 10-25-05, 06:45 PM
Grady's Avatar
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 13,928
Upvotes: 0
Received 0 Votes on 0 Posts
Good Job

Glad you got it fixed. BTW, I've never seen a gauge glass on a residential tank. On some tank drains, if you take the screw out of the center of the valve handle, it allows air into the tank for faster draining. These are usually marked on the plate (washer) under the screw. It's worth a look. If you have automatic air vents on the system, screw the caps down tight. Automatic air vents & conventional expansion tanks are a bad mix.
 
  #11  
Old 10-27-05, 04:03 AM
Member
Thread Starter
Join Date: Feb 2005
Posts: 36
Upvotes: 0
Received 0 Votes on 0 Posts
Spoke too soon. On the 4th day of operation, I noticed the pressure building up in the system to 28 psi. I opened the drain valve at the return to see if any air would come out, but none did - pressure did drop. I have noticed that the expansion tank is pretty full now as compared to the last three days. I'm not sure of how the expansion tank works, but it seems like whatever water goes in cannot come out. The only valves at the expansion tank are the shutoff valve from the boiler/reducer vavle and the drain valve to drain the tank. Like I stated before, under, but connected to those two valves is a bleeder valve. If I shut the water off going to the expansion tank from the boiler/reducer and open the relief valve and the water does not drain from the expansion tank, what does that indicate? What should be replaced? As always, thanks for any help.
 
  #12  
Old 10-27-05, 07:00 PM
Grady's Avatar
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 13,928
Upvotes: 0
Received 0 Votes on 0 Posts
Rcjb

Can you host some pics & provide a link? Might be a big help.
 
  #13  
Old 10-27-05, 08:41 PM
Member
Join Date: Nov 2002
Location: Massachusetts
Posts: 1,816
Upvotes: 0
Received 0 Votes on 0 Posts
Leaks....

either your DHW heat exchanger is leaking into the boiler water or the PRV is leaking into the boiler water. Try recharging the expansion tank as before only when you get your 12PSI into the boiler from a cold fill, shut off the makeup water supply and run it for a few days. If It runs OK and no large increase in pressure, then replace the PRV. If it continues to get higher you know the DHW is leaking into the boiler water circuit. Most likely a tankless coil.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


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