Strange occurrence....

Orple

So I'm still waiting on my new 0-30 gauge to replace the one that reads all kinds of crazy high pressure (it should arrive tomorrow), so in the meantime I decided to pipe in an old gauge my dad had lying around just to see what it would read when I fired up the boiler.



It read 0 psi for the entire cycle. "Stupid gauge," I said; "must be broken." I was pretty confident because I had re-piped everything that day back to the boiler tapping, so I know everything in the pipes is clear.



Just for fun, and because I apparently don't mind risking my new 0-3 psi gauge to potentially excessive pressure, I piped that in in place of the old gauge AND IT READ THE SAME THING. It did, however, read 0.2 psi right before the thermostat was satisfied, but otherwise was a solid 0 for the rest of the time.



How can this be? My connections are all tight (as tight as a 12" pipewrench will make them), and sealed with either pipe dope or teflon tape, and I couldn't see or hear any leaks in it. It can't be possible that I'm running a system at 0.2 psi, is it? Especially given that the broken gauge reads between 15 psi (cold) and 27 psi (peak).



Any idea what's going on here?

joewolf

gauge

hi there my 0 to 15 psi never reeds anything ,on a 300,000 btu low pressure boiler even after a long cycle i never see that gauge move , i open the relif valve and nothing came out,i think is a common thing i have reed same on this wall same boiler only produce ounces no pound.

conversiontime

congratulations

Your systems is well balanced and boiler is likely sized correctly if you see that low pressure during normal burn cycle. My 0-3psi gauge also barely flickers during normal cycle as satisfied by therm. I did run it purposely on a 10 degree swing one day it and did start to build pressure after about 45minute straight burn. At 45 minutes it rose to .5lb and by 55 minutes it was up to 1.5 so I ended the experiment.



As a side note the rad steam vents start hissing at as little at 1.0 pressure so loud rad vents are almost always pressure related.

Orple

Confirmed

I'm not sure that it's an unmitigated good, but I did get my new 0-30 gauge today and piped it into the other tapping, and it confirmed the reading of the 0-3 (that is, 0 psi), so at least I know the old gauge reading of 27 psi was way off (that sucker was sealed shut with crud when I took it off).



I actually suspect that I have a hole in my boiler, because while the main lines heat up super quick, once things get to the radiators they take forever to warm up -- and yet the boiler is running at zero pressure. I wonder if I'm sending all my steam pressure through my chimney.



If I recall correctly, I have to flood the boiler to find this out, but will need to research this in more detail. Back to the books for me.

mcsteamy

Ugh...

You're operating on a number of misconceptions here--probably due to what you thought was "right" based on the old, broken gauge.  A steam system running at 20+ pounds of pressure would be an absolute disaster.  These things are designed to run on OUNCES of pressure.  You don't heat the house with "steam pressure" but with low pressure steam.  And it does take a very long time to heat up a large radiator. 



If you have a leak or a hole in the boiler, you'll know it because you'll be adding tons of make up water and the chimney will have lots of white steam pouring out of it.  If this isn't the case, you probably don't have a hole.



As has already been said, if you don't have high pressure, you probably just have a system working properly.  We never shut off on pressure with almost 300,000 input BTU, which is almost certainly quite oversized.



If you have good main vents, properly adjusted radiators, and lots of added insulation in the house, you won't build more than a few ounces unless and until you try to recover from a significant setback which will fill all the radiators all the way across.  When that happens, you'll see pressure start to rise on the gauge.

Orple

Sorry for the misconceptions

Trying to get up to speed on this. I'm fine with the system running on ounces of pressure (that's why I installed the 0-3psi gauge). I'm just put off by the fact that it runs at 0.0psi for (usually) the entire cycle. Let me explain my thought process, and maybe (hopefully!) you can help me straighten this out.



I get that the system can run at 0.0 psi when the steam is filling up to the mains (given adequate main venting, which I believe I have). What I don't understand is that, while the steam moves remarkably fast through the mains, the whole process seems to go into slow motion when it hits the radiators. Granted, the boiler is now filling 5 radiators with steam through small vents rather than one main through large vents, but the process is so much slower that I expected to see some pressure reading--even in ounces--on the gauges at this point. I figure the boiler isn't slowing the production of steam, and if there isn't a leak somewhere the trapped steam should result in at least somewhat higher pressure.



I'm not trying to argue the point, because I take for granted that most of the folks reading this will know steam better than me; I'd just like to understand what's happening.



Two additional notes that may (or may not) be relevant:



1. I currently need to refill the boiler about once per week; my understanding is that this is more than should be expected.



2. All of my existing radiator vents are cheap-o's and have definitely seen better days. I'd be surprised if they were venting adequately, but I suppose it's possible. In any event, I have the new Gortons in hand; my next project is to go around and replace them all.

JeffM

condensation

The reason that you don't see the pressure rise as the steam starts filling the radiators is condensation. If the radiators were already hot when you sent steam to them the pressure would indeed begin to rise, but with them cool what happens is that for a while all of the steam being sent into the radiators is condensing back into water. When that happens, the water is taking up less volume than the steam that it came from so the pressure can't rise yet.

mcsteamy

Refilling

Having to refill the boiler is not usually a good sign.  However, it does not necessarily mean that you have a hole in the boiler.  Look at what is coming out of the chimney--you'll see a lot of steam if you have a big crack or hole.  



Refilling can simply be a symptom of leaks somewhere else in the system.  I've been using more water than I like, but I suspect it is NOT the boiler.  I had a bad main vent I just realized had failed open and was venting steam.  It was in a dark corner up in the joists, and because things were at low pressure, wasn't very visible until I hit it with a bright flashlight.  Then there's a leaking packing on a shutoff that loses half (if I had to guess) a cup to a cup of water on a long cycle.  Then there's the water vapor being lost out of my working main vents (which are actually traps), one of which flutters a bit.  Then a few other leaks here and there around packing nuts, leaking ir spitting vents, you name it.  It all adds up.  I was using close to a gallon a week.  After tracking down all the problems, it was pretty clear why.  If you start taking a close look, you might find something similar. 



Once you get those radiator vents replaced and check for leaks, check back if it still doesn't heat or uses water.  It takes an awful lot more steam to heat up a radiator compared to your basement pipes than you would think.  There is an awful lot of uninsulated pipe there if you were to stretch it all out...  Take a single 15 section two column 36" radiator--over 90 feet of, say, 2" pipe "equivalent".  Probably more "pipe", and larger, than all the pipe in the whole basement.