Low Pressure: Trouble Adding Water to System

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Old 11-30-09, 10:19 PM
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Low Pressure: Trouble Adding Water to System

Here is a quick history. The house has a Slant/Fin boiler. It had low pressure and when we tried bleeding the upstairs radiators air would be sucked IN rather than be pushed OUT. The boiler read about 8-9 psi. Some time later someone mistakenly shut a switch off that was to the boiler and nobody could figure out why our boiler stopped working all of a sudden. So a plumbing service came and two younger men (I'm assuming recent HVAC grads) came in and within a minute noticed the switch was OFF and the boiler was back on. I told them about the low pressure and they decided to add water to the system. One plumber grabbed some kind of tool (I can't remember what it was) and it appeared he adjusted something on the Reducing Valve and opened the valve next to it and water quickly entered the system. They then bled the upstairs radiator (which was full of air) and proceeded to leave. The pressure though kept going up and nearly reached 30 and was dripping from the pressure relief valve. I wasn't sure what to do, and lifted the relief valve briefly to release some water into a bucket. The pressure since has been very low (close to 0). When the boiler turns on all the radiators get warm (even the upstairs one that didn't before). I was concerned about this low pressure and thought I could add water to the system. After staring at the reducing valve for a while I concluded I couldn't remember what the guy did to manually add water. I have adjusted the screw on top of the reducing valve clockwise to try and increase pressure, but it has only gone up very slightly (about to 5psi) and it seems that I turned it quite a bit. The reducing valve is a B & G reducing valve and does NOT have any "fast fill" (or whatever it's called) lever on it. Also, the valve leading to the reducing valve is closed and the valve on other side of the reducing valve (the valve close to the expansion tank) is open. It is how the HVAC guys left it. I do have pictures of it if necessary. I just want to know how you add water to a system that needs pressure manually without the fast fill feature. Sorry for the wordy question, but I wanted to be as specific as I could be.

Thanks,

Mr. S
 
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Old 12-01-09, 04:59 AM
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Post some pics if you can.

Be sure the valve that is between the potatable water and the back flow preventer / fill pressure reg is open and also the one between the fill pressure reg and the system is open.

You will want to loosen the adjuster ( turn counter-clockwise) some number of turns. Older pressure regs never seem to fill the system fast but they do often seem to over pressure it. Since everyone seems to crank down that adjuster.

Let it fill for a few hours if it's low, and keep an eye on it. Once it stabilizes, turn it in if its low, or out if its high.

If it's high you can let some water out, but don't use the safety relief valve to do it, use the boiler drain and a hose.
 
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Old 12-01-09, 06:06 AM
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Call em back

Sounds like my plumbers/plumbing recent experience
Why didnt plumber just stay there ; stick around long enough to make sure the system filled and pressure turned out to be correct ? Just another sloppy take the $$ and run out door without finishing the job being paid to do
Why should any homeowner be touching any of these pipes/valves when plumber was just there and supposedly fixed something. Really great
If it's gonna take hours to really refill or whatever the plumber can leave, go do another job and come back later (next day) and THEN get paid for a fully complete job... not just run out door with the $$ and leave the homeowner hanging out in the wind (hoping things will be ok)
Sounds like again some young'ens didnt really know enough what they were doing and all the side-effects
Call the plumber back to fix/do the job right they were paid for in the first place!
 
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Old 12-01-09, 02:10 PM
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Low Pressure

I haven't had time to really try any of the suggestions on the boiler. I did take a few pictures so you could have a better look:

Pictures by MisterSelatcia - Photobucket
 

Last edited by NJT; 12-01-09 at 05:10 PM. Reason: changed individual photo links to one for entire album
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Old 12-01-09, 03:35 PM
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Originally Posted by Mister Selatcia View Post
Also, the valve leading to the reducing valve is closed and the valve on other side of the reducing valve (the valve close to the expansion tank) is open.Mr. S
I deleted my post - I hadn't looked at the photos first.
 
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Old 12-02-09, 06:23 PM
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Originally Posted by TOHeating View Post
Post some pics if you can.

Be sure the valve that is between the potatable water and the back flow preventer / fill pressure reg is open and also the one between the fill pressure reg and the system is open.
Would that indicate the two valves that are in the pictures I have taken? When doing this, does it matter if the boiler is still hot or should I wait until it cools to do this?

Mr. S
 
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Old 12-02-09, 06:34 PM
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If the fill pressure reg works then those two valves should remain open, at least until all the air is scrubbed out.
 
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Old 12-03-09, 03:23 PM
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Adding water

Okay, I think I found the problem to why I couldn't add water. There was a different valve that I thought was open that was not. Before I added the water to the system, I wanted to make sure it was safe. How do you know when it is safe to add water? Basically, how long do you let your boiler cool down before adding water to the system?

Thanks,

Mr. S
 
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Old 12-03-09, 03:34 PM
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100 to 120 degrees on the boiler thermometer should be cool enough to add water with no damage.
 
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Old 12-03-09, 09:40 PM
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Pressure strange?

Okay, here's an update. I finally managed to add water to the boiler. I slowly added water until it reached ~12psi. The boiler remained off for about 45 minutes and then fired up. As it heated, the pressure rose close to 30psi to heat up the house 1-2 degrees. Since it was rising so fast, I turned the heat to "off" on the thermostat to turn the boiler off. When I got home later, the boiler cooled down and the pressure was reading close to 0psi. I turned thermostat heat to "on" and the pressure again rose to close to 30psi. What could be causing this?

Thanks,

Mr. S
 
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Old 12-04-09, 06:07 AM
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Sounds like a water logged air cushion tank.
That green tank that is up in the ceiling, between the joists is designed to have air and water trapped in it.
They sometimes get full of water with little or no air left for the water to expand against.

There was a previous thread with a great posting about how to drain the tank.
 
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Old 12-04-09, 05:19 PM
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Originally Posted by TOHeating View Post
Sounds like a water logged air cushion tank.
That green tank that is up in the ceiling, between the joists is designed to have air and water trapped in it.
They sometimes get full of water with little or no air left for the water to expand against.

There was a previous thread with a great posting about how to drain the tank.
It looks like you were right on the money. I drained the expansion tank completely and then refilled the system to ~ 12 psi. The boiler fired up later and the pressure didn't continuously climb like it did before, and stayed right near the 12 psi mark where it is now (with the boiler cooling). Thanks guys!

Mr. S
 
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