No boiler pressure

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  #1  
Old 01-26-09, 06:28 PM
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No boiler pressure

My baseboard heat system is has gone from not heating well to pretty much not heating. Boiler fires up and gets hot. Lots of gurgling and sloshing in the pipes, but i cannot get the system to bleed out the air. Spits and sputters a bit, but no longer gets to a steady stream of water on any of the registers. Checked the gauge on the boiler and it is showing temps between 180-200 deg, but zero pressure. I'm thinking something is up on the inbound water feed side and I'm getting no water replacement. There is a B&G model B-8 reducing valve on the feed line. It has a 12psi stamp on it.
Everything i seem to read indicates i have a low water condition leading to zero pressure. I see no way to bypass this particular valve to manually introduce more water into the system to build up the pressure.
Anybody have some advice? Am I on the right track or in the weeds?
Peerless MCB-097 boiler
Thanks
 
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Old 01-26-09, 07:07 PM
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You are on the right track. With no pressure, there is something wrong with the automatic fill valve.

Does that pressure reducing (fill valve) have a manual, fast-fill lever on top? If so, try lifing it.

Check that there is not an isolation valve shut ahead of the fill valve.

That B&G valve may have a strainer. If so, isolate the B&G PRV valve, unscrew the strainer, and see if it's clogged.

If all else fails, replace the pressure reducing valve.
Doug
 
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Old 01-26-09, 07:48 PM
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In a heating emergency, you can create a cross connection using a washing machine hose... and fill the boiler that way... but you must let the boiler cool first...and you must proceed with caution because you can very easily over pressure the boiler... connect a hose to a boiler drain, and the other to a hose spigot on the house water ... (washing machine?) ... you need the washing machine hose to do the 'sex change' on the hoses... VERY SLOWLY! open the valves and fill the boiler while watching the pressure gauge. You will have to bleed air out of the system after filling, and after bleeding maybe add more water... REMOVE HOSES AFTER FILLING! because you can contaminate your domestic water with such a cross connection if the boiler water flows back into your domestic side. (it shouldn't, but it could)

Since you have no pressure in your system now, it is an excellent time to check the air charge if you have a bladder type expansion tank and adjust if necessary...

Make sure that the reason you have no pressure is not because there is a leak somewhere!
 
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Old 01-27-09, 07:51 AM
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Originally Posted by NJ Trooper View Post
Make sure that the reason you have no pressure is not because there is a leak somewhere!
Good point! There must be a reason why the system became depressurized. Something haywire with the pressure reducing valve (auto fill valve) could explain why the system doesn't get repressurized, but doesn't explain how it became depressurized in the first place.
Doug
 
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Old 01-28-09, 09:06 PM
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Thanks for the feedback. When I get a sec, i will try to take a crack at the suggestions. Due to my long work days and lack of time, I did schedule a service call with the installer of the existing boiler. Not coming until Friday, so i may have a little time to fool around w/it. Will let you know one way or the other.

Regarding how i got to this depressurized state. This seems to be the end of a very long, slowly degrading situaion...like over the last couple of years. System wasn't working great, but was working. I then cut a register out of the system, did some air bleeding and got it going again. Being a serious novice, I did not think to check the pressure at that point. System was not performing well, but getting by. some registers would not heat up. The latest round started when I again tried to bleed off some air to get the disfunctional registers working. Bad went to worse and here I am today.
I think i may have had a repressurization problem beginning when I cut that register out and it hasn't been right since.
 
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Old 01-29-09, 09:55 AM
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Question for the experts.

After reading the thread, I am wondering what percentage of water is lost in a typical hydronic system running as expected.
does the automatc refill valve continually allow water in to the system as needed or mostly just in a maintance situation?
If water continuosly enters the system is it usually in very small unmeasurable amounts?
Thanks guys,

PS ,this site is killer, Its like watching 'This old House'. except you read- and look at pics !Beer 4U2
 
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Old 01-29-09, 03:45 PM
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Normally, the pressure will only go down to the setpoint that it was filled to, and the regulator is set for. The press. will rise a few lbs. with temp. increase. If it rises too much, then hopefully the relief valve will open, which means check the air charge in the expansion tank.
A drop below the set point indicates a leak, which is one reason the water feed is left off, by some, after the initial fill, so a leak is noticable on the guage if it's in a wall.
Tom Beer 4U2
 
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Old 01-29-09, 07:13 PM
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auto fill open or closed

The percentage of presusre lost and the postion of the fill valve are current topics for me!

I have pondered the pros and cons presented in this forum regarding the fill valve position and recently I tried closing the fill valve as an experiment. to see the rate of loss (root problem is constant air in the system).

Turns out that I lose pressure in about a week or less. PRV is set at 12PSI and as long as I leave the fill valve open it hangs steady.

If I close it like I did this week, within a few to 5 days the presuure drops to zero. My assumption is that this indicats a leak in the system!

I have looked at most of the visable plumbing around the boiler and I don't see any leaks, but I have 4 zones with lots of check valves and pipes behind walls so I suppose the leak could easily be hidden.

The circulators are located on the return and can be valved off there.

I would think the next step is to isolate each zone one at a time to isolate from the system and run like that to identify the problem to a subset of plumbing but the outflow goes to all zones with no ability to valve off.

Any advice?

I am I right that 5 days is too fast to lose pressure?

Any hints on locating problem?
 
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Old 01-29-09, 07:58 PM
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Unfortunately I have to agree that you do have a leak somewhere... if a system is watertight, it wouldn't lose any water at all...

It doesn't take a lot of loss to drop the pressure to zero, probably well under a gallon, maybe even less than a quart. Problem with finding leaks in a heating system is the fact that you rarely will see water leaking. It usually dries and evaporates before it even hits the floor. What it will do though is leave a telltale mineral deposit on the piping. I'm not talking about the light greenish staining that's left behind from a pipefitter who didn't wipe the flux from a solder joint... you would know it if you saw it. In fact it might look something like this:



if it went long enough. (this one was probably leaking for at least 15 years, and only discovered during a renovation)

So, don't look for water, you probably won't see any.

You might have to install some valves...
 
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Old 02-06-09, 08:54 PM
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problem resolved

Problem was a bad reduction valve. No water coming into the system after i had cut out a register and messed with air in the system.
 
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