New vents, steam still uneven

Kevin_7

About a month ago, my 112,000 BTU Utica Boiler was replaced with a 135,000 BTU Smith unit. I have about 84 feet of main on a single run that serves 10 radiators with a total EDR of about 298 (according to the tables in Lost Art). With the old boiler, the last few radiators never got blazing hot, but they were definitely hotter than now.

Right now, the 7th radiator (located on the 1st floor) is the last one that seems to heat well. Radiators 8 and 9 are on the second floor -- #8 (26 EDR) gets reasonably hot (though not all the way across), and #9 (22 EDR) is ice cold. In fact, the riser up to #9 is only hot about one-third of the way up. Above a couple feet, the pipe is cold. Radiator #10 (40 EDR) is on the 1st floor and is also cold. Meanwhile, the rads earlier in the loop are blazing hot, and most are hissing significantly. The thermostat is in the living room, where rads #7 (hot) and #10 (cold) are, so most other rooms get much warmer than the thermostat setting...

I was advised a while ago to get a Gorton #2 for my main vent. This was installed earlier in the week, so I now have a #1 and a #2 on the main. But there has been little (if any) difference. Gorton recommends a #1 for every 20 feet of main, so I would think I should be all set with the #1 and #2... The pressuretrol is set to cut in at .5, with the differential set just a shade over 1 psi. What else could be going on here? Anything obvious that I'm overlooking? Thanks for any help, I'm still pretty clueless about all this. kevin.

[Deleted User]

one pipe or two pipe steam?

for starters...

Are the riser tops vented?

Pipes insulated throughout?

Noel

Kevin_7

Whoops, sorry about that

One-pipe steam. No vents at riser tops, just on each radiator and at the the end of the main. The main is well-insulated, the risers (5 go to the 2nd floor) are not.

[Deleted User]

To rule out venting problems,

> One-pipe steam. No vents at riser tops, just on

> each radiator and at the the end of the main.

> The main is well-insulated, the risers (5 go to

> the 2nd floor) are not.

[Deleted User]

To rule out venting problems,

Pull out a vent on a cold radiator and see if air comes out, and how strongly.

If it isn't there, it is a steam supply problem.

Firing rate, dirty water, piping at the boiler, equalizer too small or bullheaded, high water line, things like that can cause it.

Partly plugged piping might, too. But not in a lot of different places.

Noel

Steamhead

Another thing to check

Does the steam fill the main first, before rising to the radiators?

When the boiler starts producing steam, it should head for the main vents, arriving there in about a minute. If it doesn't, you may need a second Gorton &2. Sometimes this is caused by something as simple as improperly reamed pipes in the main.

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Kevin_7

Current Status

OK, earlier today while everything was running and the radiators were hissing, I checked out radiators 9 and 10 of 10 (both cold). Number nine was hissing quite loudly, and when I pulled the vent off, there was a significant amount of air coming out, making a low pitched "whoo" every couple seconds (as if someone was blowing across the top of a Coke bottle). Radiator 10 acted the same way, though there was no noise, and less air coming through (though I could still feel it).

In the basement, there is a Gorton #2 about a foot or so from the end of the main, and a #1 at the end in a T. (Not the right placement, I know. But anyway...)

Just now, I cranked up the thermostat and sat in the basement for 20 minutes or so. This is what happened: Boiler comes on, fires for 3-4 minutes, then shuts off. After about a minute, it fires back up again. A few minutes later, the water in the sight glass (which is clear) starts to bob. The beginning of the main starts to get hot, and there is air audibly coming out of the Gorton #2. After about a minute, the end of the main near the #2 starts to get hot. The boiler shuts off again. After a minute, it fires back up, the water begins to bob again, etc. The #1 spits just a drop or so of water. At this point, the water in the sight glass is getting pretty brown. It runs for a few more minutes, then off again for a minute. Then it fires back up, and has now been running for about 10 minutes straight. Radiators 1-7 are starting to get hot. The riser to radiator 8 is still cold, but will get warm soon. The riser to radiator 9 will only get hot a couple of feet up, and stay cold the rest of the way. The radiators are hissing again (but aren't spitting water or anything).

So, I guess I'm still lost. I think the whole system should probably be flushed (which I hope to do this summer). In the meantime, does any of what I've said raise any flags? Thanks a lot for your help, I've learned a ton from The Wall. kevin.

Unknown

Sure does

It shuts off on pressure before the radiators are hot. That means it is shutting off on air pressure, because if it were steam pressure alone, the pipes and radiators would be hot when it shut off.

More air vents are called for, by the on and off action. The locations of them should be determined by where large amounts of cold piping exist when it shuts off on pressure.

Make sure it isn't the thermostat heat anticipator shutting off the burner, and that it is the pressure control.

The faster you get the steam to the radiators, the sooner the rooms get warm, and the less fuel it will take to do so.

Noel

Kevin_7

Makes sense...

You mentioned location of a new vent... As in, it shouldn't be at the end of the main with the other? The main is insulated all around, but I have 5 2nd-floor risers that are uninsulated. They are placed pretty evenly around the loop. Also, at the risk of looking like a complete rookie, how would I tell if it was the heat anticipator shutting off the burner?

Thanks again for your help, you have no idea how much assistance this has been. kevin.

[Deleted User]

I think that

"bobbing" you see in the gage glass could be the symptom to what really ails your system. We call that surging. If while the boiler is running, water comes down from the top of the gage glass, that is priming.

Both are a no-no. The surging could lead to a momentary low water condition that trips the low water cutoff. Steaming stops and has to start all over again when the burner fires.

That sound "like someone blowing over a coke bottle" is symtomatic of some really wet steam. Another description is that it sounds like a hound dog panting. That is what we hear when the boiler is priming. There could be so much water in the risers to the affected radiators, that the steam never gets there.

Sounds like a really good drain, flush, and skim, is in order now. The crud in the system will move easier when hot. If you allow the system to get cold, much of that stuff will solidify against the inside of the pipe and boiler surfaces. Get it while it's hot.

If you want to see what happens when a boiler is surging & priming, go to the kitchen. Put a pot of water on the stove. Bring it to a boil. Small bubbles, right? Now pour some oil on that boiling water. See how the steam that was rising off those small bubbles is now smothered? Notice how what steam does escape comes out with large bubbles. That is probably what is happening in your boiler.

The crud you see in the gage glass is also lying on top of the water. That crud forces the steam upwards in large bubbles, not small ones, and much of the water in those bubbles flies out into the mains with the steam. Steam and water are close cousins. They just don't mix well.

A quick test, named for a gentleman in Minnesota, will tell the tale. While the boiler is steaming, place a pail under the drain nut on the bottom gage glass cock. Loosen the nut. If you get clean, dry steam, I'm all wet. If however, copious quantities of water come out with the steam, we got lucky. Drain it. Flush it. Skim it.

Ain't steam fun?