Boiler T&P

Reply

  #1  
Old 11-10-18, 02:21 PM
Member
Thread Starter
Join Date: Mar 2008
Location: Boulder, CO
Posts: 1,020
Boiler T&P

My neighbor called this morning with a dripping T&P. They had to leave town until Tuesday. I have done lots of piping work, but don't know boiler systems. There is an isolation valve for the boiler supply, but it is a gate valve and seized. Old gate valves never close anyhow. I can shut off house water at the meter. If I turn all of the zone stats off, will that prevent a flood of water if I remove the T&P? Am I out of my depth?

The boiler is in the basement with 2 stories above it.
 
Sponsored Links
  #2  
Old 11-11-18, 08:20 AM
Forum Topic Moderator
Join Date: Sep 2005
Location: USA
Posts: 4,264
I've moved your post to the boiler forum. You may get some more responses here.

-Mike
 
  #3  
Old 11-11-18, 08:23 AM
Forum Topic Moderator
Join Date: Sep 2005
Location: USA
Posts: 4,264
Unfortunately, to replace the T&P valve, you need to drain the system down to the level of the valve... usually that means the entire system. It's a pretty easy process, turn off the incoming water, connect a hose, and drain it out.

If there are some working valves in the system, you might be able to keep some of the water in the system.

When you're done, fill it all back up again to the same pressure. What type of heating system is it? (cast iron radiators, baseboard, etc?)
 
  #4  
Old 11-11-18, 11:27 AM
Member
Join Date: Oct 2013
Location: United States
Posts: 2,139
Depending how your system is piped and what you have for valves and zone components if multiple zones apply you may not have to drain the whole system.

Pics of the boiler and piping would be very helpful.
 
  #5  
Old 11-11-18, 12:31 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 46,287
It may not just be a defective P valve. Boiler pressure when running is also an issue.
Pictures will help us to help you zero in on the problem. How-to-insert-pictures
 
  #6  
Old 11-12-18, 04:23 AM
Member
Join Date: Jan 2017
Location: USA
Posts: 347
Boilers are not fitted with T&P valves, they use pressure relief valves only. Storage water tanks use T&P valves. And as 'PJ" stated more information is needed such what the boiler pressure is and the pressure setting of the relief valve.
 
  #7  
Old 11-12-18, 03:35 PM
Member
Thread Starter
Join Date: Mar 2008
Location: Boulder, CO
Posts: 1,020
Thanks

This is a job for an HVAC pro, not a handyman. I'll just keep emptying the bucket 3 times a day until they return. There is no floor drain in the mechanical area, so I was very afraid of unscrewing the valve and emptying the 25 vertical ft of piping above it.
 
  #8  
Old 11-12-18, 05:04 PM
Member
Join Date: Oct 2013
Location: United States
Posts: 2,139
The only problem with emptying that much water constantly is as it empties so does it refill because of the auto feed valve and every time fresh water is introduced into the system it brings air and by the time it is repaired, that system might be completely air bound.

Pray the weather holds up so nothing freezes. Air in the system will prevent water circulation so eventually you will have no heat.
 
  #9  
Old 11-13-18, 07:23 AM
Member
Thread Starter
Join Date: Mar 2008
Location: Boulder, CO
Posts: 1,020
It has been very cold, but the house is still warm. They return today and can hire a pro. I have been emptying the bucket into the washing machine and by today the tub was pretty full, however much water that is. I'm glad I didn't mess with the valve. In the words of Clint Eastwood, "a mans gotta know his limitations".
 
  #10  
Old 11-13-18, 09:46 AM
Member
Join Date: Oct 2013
Location: United States
Posts: 2,139
Sounds like you dodged a bullet. Thanks for the update.
 
  #11  
Old 11-13-18, 12:00 PM
Member
Join Date: Mar 2010
Location: USA
Posts: 3,100
Did the pressure relief valve drip continuously or did it drip only when the boiler cycle on and internal pressure rise?

Does the system have an expansion tank?

If some excess air got into the system, the upper floor radiators would not heat up as well but also there would be less tripping of the pressure relief valve. A properly prepressurized and functioning expansion tank will allow all of the air floating around in the system to be bled (manually) without resulting in excessive pressure rise during normal cycling of the system.
 
  #12  
Old 11-13-18, 09:44 PM
Member
Thread Starter
Join Date: Mar 2008
Location: Boulder, CO
Posts: 1,020
This thread has legs. The system has an expansion tank, but I have no way of knowing it it is functional or has a blown bladder. Also don't know if it leaks more when heat on and pressure higher. It was probably leaking 6-7 gallons per day.
 
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