Tim question on 960,000 boiler with 4 pilots....air shutters

JUGHNE

These burners have the standard air shutters on each burner. However there is a sliding panel that seems to be another air adjustment. With the panel all the way out there is almost 2" to the adjustable butterfly shutter. It seems the intent for this panel (numbered 1 & 2 in the picture...total of 4 for 16 burners) is to provide more air adjustment? The burners had butterfly completely open and the slider pulled all the way back as in the picture.
Some guidance here would be appreciated...Thank you

Also would these 4 pilots have had a pilot gas regulator for the 1/4" line, previous maint man said pilot were often going out. But every thing was very dirty and some T-couples nearly burned thru.....Thanks again.

Steamhead

While waiting for Tim, I'll say that you should never make any adjustment to a combustion appliance without using a digital combustion analyzer.

Sure these units aren't cheap, but they're much cheaper than lawyers.

JUGHNE

I know they're not cheap, have the Testo 327 here.
Was going to start out with the air settings that were there....wide open...NG.
It appears 2 methods of air control for burners. That is the question of dual air adjustment??
Light off in maybe 2 weeks. 1963 Bryant. Was neglected most of its life and then set abandoned for one season. Holding 15 PSI for 2-3 months so far.

nicholas bonham-carter

That is a difficult job for the combustion analyzer, as there would be 16 points of adjustment, with the analyzer only giving an average of the whole.
Are there any markings on the boiler to identify who the original manufacturer was? If the source can be identified, then maybe original instructions could be found for the burners, and their adjustment.
When it was converted from LP to natural gas, maybe the pilot orrifices were not changed.--NBC

bob_46

At Weil-Mc Lain's three day school in Michigan City back in the 60's the way they taught to adjust primary air on atmospheric burners was. Set gas press. to nameplate , open all the butterflies and light burner, look into the firebox just above burners focus on the wall of the firebox. Close one of shutters until it looks like a light is shining on the wall then close it until the light just goes out. Repeat on each burner. Adjust the secondary air (the part with the number 2 on them) with a shake-bottle for best CO2 .

JUGHNE

Thank you Bob, that gives me a head start......primary & secondary air adjustment. I assume you meant to start fully open on butterflys and close to see the light (maybe a touch of yellow and then OPEN until it went away. And I actually have the shake-bottle for best CO2 but will use the Testo as my fluid is probably 30 years old.

NBC, not only 16 butterflies but 4 secondary slid in air baffles....does that give us 64 variables? It has 3 10" flue pipes/draft hoods. This is a 1963 Bryant.
Thanks to all.

bob_46

Big typing error ! close the shutter until the light goes on then OPEN it until the light goes out. Sorry

Tim McElwain

Adjust the air shutters only after making sure your gas pressure is good. Then check all the burners orifice sizes to make sure they are correct. Take the input and divide by number of burners and the check rating plate for manifold gas pressure. Once that is all set with the burners all in place close them about half way. Then close one at a time until the flame just starts to turn yellow then back off about a 1/4 tun and lock them up. Cycle the burner several times to make sure the light safely (in 4 seconds or less). The doors marked 1 and 2 are for secondary air and should be positioned using a combustion analyzer adjusting them for the best CO2 and O2 with the lowest excess air and low CO. Then clock the burners using the test dial on the meter to make sure the input matches the input on the rating plate or close to it. Slightly under is okay.

Pull the pilots and clean the orifices if this is natural gas the orifice size will be around .018 or so or close to that. The pilots would not be regulated as they should be on line pressure (same pressure as is coming out of the meter). Replace the thermocouples with either Honeywell Q340 or Q 309 or Baso Gas Controls LLC Husky thermocouples.

I use three combustion analyzers to test multiple burners like these or sometimes four depending on the number of burners and sections. I have a piping set up which fits into the flue passages I use which measure six burners at a time maximum and I can just disassemble it for less burners. Make sure your test probe is getting all the way into the flue passages and not getting diluted by air entering through the draft hood.

Eight burners - eight sections 960,000 BTU's that is 120,000 per burner at 3.5" W.C. pressure that would be a # 8 or # 9 drill for each burner.

Hope that helps, sorry for the delay but I am very busy with training along with caring for my wife.

JUGHNE

Tim, thank you for your time and consideration. You and Bob seem to agree on the air adjustment and comb testing.
However this boiler is so close to the wall that I can just stand behind it if I empty my bib pockets. I was just back there today finishing up the 3 flue pipe connections. I don't think I can be there when the boiler is firing.

There are 16 burners with 4 secondary air slider adjustment.
They are the correct size as checked with the gauging drill...about a 23.
The pilot orifices are 2 small pinholes each. A single wire out of a wire brush will just fit inside. Pilots are clean and new T-couples installed.
I lite the pilots today to check the safeties. They burn about 2 1/2" tall and are fairly noisy.
This was converted fm LP to NG years ago. If the LP pilots were left in place would they produce that tall of a flame.
No pilot regulator, running of meter at strong 5" WC.

With MGV safety switch closed, (on ohm meter) It took almost 90 seconds for switch to open when pilot gas was shut off.

Thanks again, and praying for your wife's well being.