Overgassing Domino Effect (Steamhead)

Steamhead

but we talked about doing some more work to his system. Those parts aren't expensive so I'm sure he'll go for it.

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Steamhead

Got a call from a friend last night

the CO alarm in his boiler room had sounded. BG&E responded and found a sooted-up older Repco gas boiler, which they shut off (their gas techs don't clean boilers anymore). He said he had been getting headaches all winter when he was in there.

The Repco was completely plugged up. The flue gasses had been coming out the front of the boiler, which set off the Nighthawk CO alarm.

When I took out the smoke pipe to clean it, I found some debris had fallen into the bottom of the chimney, which blocked about 20 percent of the smoke pipe as it entered the chimney. There was no soot in the chimney itself.

The Repco was rated at 200,000 BTUH input. When I restarted it the first thing I did was clock the meter, while giving the boiler a chance to warm up and stabilize. IT WAS FIRING AT ABOUT 250,000 BTUH! The regulator was screwed down. Sound familiar? I checked the CO and it was 1800 PPM air-free!

Reducing the input to 200,000 BTUH caused the CO to drop rapidly. It finally stabilized at 60 PPM- not as low as I'd like but certainly acceptable. There was plenty of draft- this house originally had a coal-fired boiler.

Now, we all know that CO, besides being toxic, is a sign of bad combustion. Soot also indicates bad combustion. And debris in the chimney definitely is a problem. However, the draft didn't appear to be that much worse with the debris in the bottom of the chimney, BUT IT COULD NOT HANDLE THE OVERGASSING. Therefore the boiler could not expel all the excess flue gas, which caused it to soot up. And because it was overgassed, the CO built up much faster in the boiler room.

WARNING TO OVERGASSERS: You might think you can get away with your dangerous habit, but if something else goes wrong with the installation the overgassing can make it much worse. I could have lost a friend because of one of you. You need to re-evaluate your technique RIGHT NOW!



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[Deleted User]

I dont understand why someone would do this

especially it seems to me that they must not have been testing the combustion gases as they were adjusting the regulator. IMHO there should be no adjustments done on anything without a combustion analyzer going. test or guess.

Steamhead

That boiler had never been properly tested, Gerry

the draft hood is in the smoke pipe, and no one had ever drilled a hole for a probe below the hood. Not even the BG&E tech who had "some sort of probe" according to the HO.

I find this all the time. To those reading this- if you're in this business and don't have a combustion analyzer and know how to use it, you're really not getting the job done right. Talk to Steve Ebels (he handles Testo units) or Alan Mercurio (handles Bacharach). I've heard good things about both brands, and both these gentlemen are Wall regulars.

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Unknown

Did you tell your friend

to invest in a rollout and spill switch for that old Repco ? Or were they on there and jumped out by another expert tech ? It happened to us a few times on a cold day - starting it up into chimney that revered flow and would blow out the rollout switch . We always kept a few extras on the truck , but I could imagine how many guys just jump em out and walk away .

Tony Conner

Every...

...accident report I can remember listed a series of events that led up to the incident. Routinely, at the start of the sequence, there's a factor that had been wrong for years, and often since "Day One" of the installation. "Oh, don't worry - it's ALWAYS been like that." Or, "Well, that's the way we ALWAYS do it."

Every so often, though, it's: "I don't understand - we never had a problem with it BEFORE."

gas man

over gassing ,well said steamhead!

Working with gas ,mainly >>>it reacts differently ,especially when cold . overgassing can cause serious delayed ignition , and it only takes a partially blocked air shutter to start making some serious CO ! Ya gotta check all equipment on installation , and before I complete any job , I check for co. ! keep your people warm >>> above all safe !