Refilling a hot water boiler system

Reply

  #1  
Old 02-23-12, 12:02 PM
Member
Thread Starter
Join Date: Feb 2012
Location: usa
Posts: 5
Refilling a hot water boiler system

Hello,

I have a Laars Hot Water boiler closed-system which was operating ok, but I needed to replace a pipe in the system.

I drained the boiler by hooking up a garden hose to the unit, opening the drain valve and then opening up all the bleeder valves on all 5 radiators (they're all on the same floor at the same height).

I replaced the pipe and now need to refill the system. I tried, but did something wrong. I closed the drain valve, and opened the fill valve while leaving all the bleeder screws open on all 5 radiators. (All other valves in the system are in the same position they were in before I shut it down). I could hear water filling in to the system and eventually water came spitting out the bleeder screws, which I closed one-by-one as they began to spit. When the last one spit, I raced downstairs and shut off the fill valve. I then started the boiler so the pump would cycle the water through. I went upstairs and checked the radiators to see if there was more air to be bled. One in particular had a lot of air, so after a long bleed with no water, I went downstairs to add more water to the system for 3-5 seconds (I think I read that somewhere). While doing this, a blow-off valve (??) opened and drained the whole system, indicating that I had too much pressure (or too much heat?). The system was on for 5 minutes yet none of the pipes were hot.

What did I do wrong?

Thanks,
-Rick

photos to follow in a few minutes
 
Sponsored Links
  #2  
Old 02-23-12, 12:08 PM
Member
Thread Starter
Join Date: Feb 2012
Location: usa
Posts: 5
I know people like photos to help diagnose the problem, so here are some that may help.









 
  #3  
Old 02-23-12, 01:12 PM
Member
Join Date: Oct 2008
Location: USA
Posts: 2,853
Likes Received: 3
What did I do wrong?
You left fill valve open without watching the pressure gauge - so the pressure got high enough to lift the safety.

Rather than refill with the bleeders open (and running up and down stairs), leave them closed and fill with the automatic fill valve (using the manual bail and while watching the pressure). Then stop manual filling and then bleed each radiator one at a time.

Why do you have two boilers? The expansion tanks should not be propped up that way - should be hanging. The piping is being damaged.

When you had the system drained, did you check the pressure in the expansion tanks?
 
  #4  
Old 02-23-12, 02:50 PM
Member
Thread Starter
Join Date: Feb 2012
Location: usa
Posts: 5
Gilmorrie,

Thanks for the advice.

I don't have an automatic fill valve.

I have 2 boilers as the house is a duplex. The other unit is working fine (well, that is to say it has other unrelated issues ;-). The expansion tanks were like that when I bought the place and the new unit which was installed was installed in the same fashion. Should I have them changed? Would it be acceptable to support it somehow?

I did not check the pressure in the expansion tanks. Thats done with a tire gauge, correct? Wouldn't the pressure read zero is the system is empty?

-Rick
 
  #5  
Old 02-23-12, 03:25 PM
Member
Join Date: Oct 2008
Location: USA
Posts: 2,853
Likes Received: 3
I don't have an automatic fill valve.
Hmmm. I think you should have one on each boiler.

I see a blue handled, manual globe valve - is that what you use to fill the boiler? If you use that, stay right there and watch the pressure gauge - you would normally want about 12 psi with the system cold. City water pressure runs about 60 psi, which is probably twice the pressure rating of your boiler (and the setpoint of the relief valve). Luckily, that relief lifted, or else your boiler could be split in mutiple parts!

The expansion tanks were like that when I bought the place and the new unit which was installed was installed in the same fashion. Should I have them changed?
In my opinion yes - and they need to be supported better than just a small copper pipe. Notice how the one expansion tank is leaning over and putting stress on the pipe?

I did not check the pressure in the expansion tanks. Thats done with a tire gauge, correct? Wouldn't the pressure read zero is the system is empty?
No, the tire gauge will read the air pressure in the rubber bladder - but only when the system is depressurized on the water side. Needs to be done every couple of years, because air diffuses through the rubber membrane.
 
  #6  
Old 02-23-12, 03:33 PM
Member
Thread Starter
Join Date: Feb 2012
Location: usa
Posts: 5
I see a blue handled, manual globe valve - is that what you use to fill the boiler?
Yes, it is.

I don't have an automatic fill valve.
Hmmm. I think you should have one on each boiler.
Would this eliminate the need for the expansion tank. I've been trying to do some reading and it seems that both devices regulate the pressure. Is it an either/or type thing?

In my opinion yes - and they need to be supported better than just a small copper pipe. Notice how the one expansion tank is leaning over and putting stress on the pipe?
I didn't think it looked right. Like I said, the GC I used didn't turn out to be so good. Is the main issue support, or is it functionality? Some pages say it needs to be mounted hanging so air does not get trapped. Others say its a bladder and you can mount it anyway you like.

The pressure relief valve still lets water straight through. System pressure is zero (I assume all pipes are empty) and I've flicked the switch on the relief valve back and forth and it still wont shut.
 
  #7  
Old 02-23-12, 03:45 PM
Member
Join Date: Oct 2008
Location: USA
Posts: 2,853
Likes Received: 3
Would this eliminate the need for the expansion tank.
No, the auto fill valvef (a.k.a. pressure reducing valve) serves a different purpose than the exp tank.

The pressure relief valve still lets water straight through. System pressure is zero (I assume all pipes are empty) and I've flicked the switch on the relief valve back and forth and it still wont shut.
Oooh, did you tell us that before? Either you are mistaken, and the system pressure is high, or the relief valve is stuck open. The relief valves need to be replaced every five years or so, as preventative maintenace.
 
  #8  
Old 02-23-12, 04:20 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
she's a very kinky girl...
Rick, check the 'sticky' messages at the top of the forum list. The one about "Relief valve spewing?..."

You absolutely MUST have an expansion tank.
 
  #9  
Old 02-23-12, 08:07 PM
Member
Thread Starter
Join Date: Feb 2012
Location: usa
Posts: 5
Oooh, did you tell us that before? Either you are mistaken, and the system pressure is high, or the relief valve is stuck open. The relief valves need to be replaced every five years or so, as preventative maintenace.
When the system purged through the relief valve, enough water came out to make me think the whole system emptied. The gauge read 0 PSI. When I turned on the fill valve, it just came straight out the relief (this valve is less than 2 weeks old). Someone suggested tapping on it, which I did and it seemed to close. I filled gently as you said, then went upstairs and bled, and now have a nice 15 PSI in the system and can run it. Which is exactly where I need to be. I have a technician coming to go a 'check up' on the unit, but it needed to be filled or he'd charge me for that. I thank you for your advice. This forum is fantastic. Its very kind of you all to give your time to help people out - it means a lot. Thanks!!

I may look in to installing a couple of these auto-fill units. They seem cheap enough ($90?) and now that I have learned how to work with PEX, I think I could tackle the job.
 
  #10  
Old 02-24-12, 07:47 AM
Member
Join Date: Oct 2008
Location: USA
Posts: 2,853
Likes Received: 3
A couple of additional observations.

See the white, plastic pipe in the photo? Is that PVC pipe (which isn't acceptable for this application)? It needs to be metalic pipe or PEX WITH AN OXYGEN BARRIER.

I don't see any air elimination devices - you need one for each boiler, properly installed. They are about the size of a tomato paste can with a tire-type valve cap on top. The cap should be left loose so air can be ejected.

Overall, your system doesn't look competently installed. It's good that you are getting somebody to look at it.
 
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