Delayed ignition

1902Shingle

Hello, hoping someone can help...  we have a gas steam boiler, it had been having small delayed ignition randomly, it had been 2 years since the burners were cleaned and that always solved the problem in the past.  Tech came cleaned burners (same guy that has serviced it for the last 12 years), while putting it back together the pilot sensor stopped working.  It was 6pm on Friday and they did not have a replacement part.  The tech installed a thermocouple pilot safety which works as its suppose to.  However we now have a delayed ignition only on cold starts.  If I turn on the thermostat it doesn't ignite, I turn it off, try again, no lite then on next attempt it will light and once it's running If you shut it off and turn it back on within a couple minutes it starts perfectly.  Any idea what our issue could be?  

EBEBRATT-Ed

Burners dirty, out of alignment, pilot in the wrong spot gas pressure issues the list goes on and on.

I would get them back asap and have it fixed.

Delayed ignition with any fuel is bad especially with gas it can/is dangerous

It probably starts better when warm because the burners and combustion area is warm

1902Shingle

Thank you!  This company is now telling me that the boiler needs replaced because of the delayed ignition.  Does that even make any sense?  Shouldn't a delayed ignition just indicate that something needs cleaned or adjusted?  Would there ever be a scenario where a delayed ignition would mean your boiler needs replaced?  I'm calling BS and have another company coming out tomorrow to take a look but was hoping someone could enlighten me

mattmia2

The only time it would require replacement is if it was caused by something that has collapsed in the boiler like some vent collector or a burner and a replacement is no longer available.

What did they replace to change the gas safety behavior, did they replace the whole combination valve? If it was the valve and the original was a slow opening valve, the new valve has to be a slow opening valve with similar timing.

1902Shingle

Ok that makes sense.  He just replaced the pilot and replaced the old safety switch with a thermocouple, he did nothing with the valve.  They never identified what the specific issue is that's causing the delayed ignition.

mattmia2

Do you have a picture of this boiler? This sounds like a pre-1960's boiler or conversion burner.

1902Shingle

Yes you're probably correct.  Pics below

109A_5

Hello @1902Shingle,
You really need someone that can actually troubleshoot the system. During the delay is there normal manifold pressure (at the Yellow circle). Is the Gas valve (Red Box) just sluggish to respond when energized (is it being properly energized), is the regulator (Orange arrow) just sluggish not immediately allowing proper gas flow to the burner, something else ?

mattmia2

It is probably something with draft or something plugged in the burners or the mixture or the boiler plugged with soot. Usually a slow to open gas valve would allow for more smooth lighting. It is also possible the valve has worn in a way that it is opening faster than it is supposed to.

mattmia2

You need someone that understands combustion to clean and adjust it. @captainco may know someone in your area that he has trained if you tell us where you are.

1902Shingle

Thank you @109A_5 and @mattmia2 for the detailed info we will keep all of this in mind when the new tech comes out tomorrow.  We are in North Central West Virginia area.  

pedmec

i've never seen burners offset from the manifold like that before so I'm wondering if there are two different style burners and he has them mixed up. The other thing he could have done is have the wrong style pilot assembly installed. They have left, right, and center strike just to name a few. also batwing style.

1902Shingle

The new guy is suspecting a draw issue, trying to get a chimney sweep out next week to clean the flu.  Checked the pressure at the manifold and said it was normal. Didn't rule out a regulator issue but said that type of regulator couldn't be replaced, I guess the entire regulator ignition system would need upgraded.  Also pulled out a pile of "lining" from under the boiler that was impeding draw (although it didn't help) and said the boiler was nearing end of life 🤷‍♀️.    Our biggest problem is that everyone around here kind of knows steam but doesn't work on it often enough to really know what the heck they're doing 😣.  Hoping we can get this sorted out before the weather turns frigid, we've been lucky this week.  

mattmia2

Did they look inside the boiler to make sure the passages were clear, probably taking the top of the jacket off?

If that valve or regulator were bad it would be replaced with a modern combination valve that would control the pilot and the main burner, contain the regulator, and connect to the thermocouple to prove flame.

1902Shingle

No I dont beleive he looked inside. He checked the burners to make sure the first guy did get them clean and they were clean, adjusted the alignment on some but nothing has made a difference.   Flames still blowing mostly out the back of the boiler.  

captainco

I see three possibilities. As much as I like to think it is a drafting problem I don't see how it could self correct after just a couple of tries. There is a possibility the gas regulator is bad. This is one case we need to watch the outlet gas pressure when it starts. If there is a small leak in the diaphragm the pressure could equalize in the off cycle. Also, I can't tell but the burners could have shifted down hill and that also could cause delayed ignition and flame rollout.

Other than a bunch of government agencies I trained in West Virginia in the 90's I don't have any current contractors listed. I imagine they may have some contractors working for them but I wouldn't bet they know what to do either. Just find a contractor that has a combustion analyzer and I will help walk him through what to do.

JUGHNE

As Matt said a new combination valve/regulator with pilot could replace all of those components.

As far as the burners being staggered, that is done so the burner tray and cabinet
could be narrower...also the cast iron sections.

The air "trumpets" are too wide to have them all lined up.

1902Shingle

Chimney and flue are completely clear so back to trying to get someone to trouble shoot.  Oddly the last two days it does not ignite on the first attempt but on the second attempt it lights right away with no delay.  Only difference is that it's colder outside by about 20 degrees. 

109A_5

Hello @1902Shingle,
I guess I am a little confused, what make these attempts (just you) ? If you are not there to babysit the situation there is no ignition and the gas just goes up the chimney ? What happens when you are sleeping, you wake up to a cold house and gas had been going up the chimney for hours ?

I would think ignition with a pilot has little to do with chimney draft. It has everything to do with burner draft mixing the fuel and air (oxygen) in the correct ratio. Did anyone do a combustion analysis ? One thing I was initially thinking is you initially have a lack of fuel or too much fuel.

Just seconds after the call for heat was the manifold pressure normal ? Where is the delay ? No fuel for a period of time or good fuel and the pilot is not igniting the air / fuel mixture coming out of the burners. Did the last tech determine what was causing the delay ? Sound like a lot of guess work going on at your expense.

Also it looks like (a non-blurry picture would help) the air shutters are missing from the burners on each side of the pilot. So if those burners have a too lean air / fuel mixture ignition may be less reliable.

I'm wondering if the burners that still have the air shutters were placed on either side of the pilot assembly ignition would be more reliable. The missing air shutters should be repaired and adjusted correctly.

Old cars needed a choke on the carburetor to richen the air / fuel mixture for a cold start. Once the engine warmed up it was not needed any more.

bburd

This:

”Also it looks like (a non-blurry picture would help) the air shutters are missing from the burners on each side of the pilot. So if those burners have a too lean air / fuel mixture ignition may be less reliable.”

mattmia2

109A_5 said:

Old cars needed a choke on the carburetor to richen the air / fuel mixture for a cold start. Once the engine warmed up it was not needed any more.

Cold gasoline doesn't evaporate very much. Natural gas and propane don't have that problem.

1902Shingle

@109A_5 because the ignition isn't reliable the boiler has been turned off at the breaker, when the house gets cold during the day we go down and  turn on the breaker.  When you flip the breaker you hear gas immediately start to flow but does not ignite.  I wait 5ish seconds and turn it off if it doesn't ignite, wait a short bit and try again then it ignites with no issue.  It remains off at night. I'll grab a new pick of the burners.  Also your pick didn't post amd I'm not sure what an air shutter is 🥴

And nobody has done a combustion test, I honestly don't know if anyone who has looked at it knows how to do that 😔

109A_5

mattmia2 said:

109A_5 said:

Old cars needed a choke on the carburetor to richen the air / fuel mixture for a cold start. Once the engine warmed up it was not needed any more.

Cold gasoline doesn't evaporate very much. Natural gas and propane don't have that problem.

It was an EXAMPLE of when the Fuel to Air ratio is wrong the Fuel to Air mixture will not ignite properly or as desired. I was not saying there should be a choke installed, just bring the burners back to original design or as close as possible.

For natural gas-fired burners, the stoichiometric air required is 9.4-11 ft.3 / 1.0 ft. of natural gas or approximately an air-to-gas ratio of approximately 10:1.

So if it is too lean you expect it to work normally ??? The air shutters were put there for a reason and the ones on the burners near the pilot appear to be missing.

1902Shingle

109A_5

Hello @1902Shingle,

1902Shingle said:

Also your pick didn't post amd I'm not sure what an air shutter is 🥴
And nobody has done a combustion test, I honestly don't know if anyone who has looked at it knows how to do that 😔

The picture days ago ? I did not post one since the 8th. I can see the picture I posted on the 8th.

These openings in the end of the burners (Air Shutters) are often adjustable. Notice the ones on either side of the pilot assembly are different (but not absent like I suspected). Red arrows versus Yellow arrows, I wonder if they were made this way so the burners on either side of the pilot could be set up a bit differently to aid in initial ignition. They may be rusted in place. They only should be adjusted by a trained tech that can verify that the CO levels are not too high, a combustion analysis.

mattmia2

It looks like someone disassembled the burner and put the air shutters back on backwards. that might be because of rust preventing them from going back together correctly.

1902Shingle

Should anything with the air shutters cause our issue? They look the way they've always looked, they've always been wide open.  

109A_5

Hello @1902Shingle,
To me (looking at your recent pictures) the two burners either side of the pilot assembly each has an additional air shutter, sandwiched together back to back, which may make the combustion air of those two burners adjustable and the others are just fixed. Without close inspection I can not be sure. When adjustable, the Air to Fuel ratio of that burner can be adjusted.

1902Shingle said:

Should anything with the air shutters cause our issue?

If they are not set up correctly I would think so.

They look the way they've always looked, they've always been wide open.

Maybe I misunderstood the original post, I thought this was a chronic problem that has been going on for many years and the only thing that gives some relief is cleaning the burners.

BTW how did the tech test the manifold pressure the pipe plug on the left side of the manifold looks untouched !

1902Shingle

It usually only happens every few years, then we have the burners cleaned and then it's fine for another couple years.  That's why I initially suspected that maybe he put the burners back incorrectly.  The tech used a meter and connected to that little port on the left in front of the burners.  

109A_5

Hello @1902Shingle,
OK with the pipe plug I did not see any fresh Teflon tape or pipe dope. I'm thinking the burner setup has been marginal for years (or from new) and slight dilapidation upsets it. Where it maybe could be setup much better and thus be much more reliable and more tolerant to lack of maintenance. It is possible certain burners need to be in the proper place but if the ones on either side of the pilot don't readily ignite I would think there is a mixture problem or the gas manifold orifice is plugged up. Once it finally gets 100% fired up are all the flames on all the burners uniform ?

1902Shingle

Thank you for your time and for all of the information, I do appreciate it.  I'm really at a loss for finding someone who has the slightest clue how to trouble shoot and fix the boiler and its suppose to turn cold this bweekend.   You're correct he did not add Teflon after testing the pressure.  Once the boiler ignites yes all burners burn evenly and blue.

mattmia2

I suggest you take @captainco up on his offer to talk a tech through troubleshooting it.

1902Shingle

@mattmia2   I will do that if I can find one that is willing.  

109A_5

Hello @1902Shingle,
Watched a YouTube video last night, the poster calmed they had a problem similar to yours. They claimed the 'Fix' was the orifices were dirty or restricted and when cleaned the problem went away. Since they really did not show much I assume it was the orifices that shoot the gas (from the manifold) into the burner assembly had become restricted over the years. This would change the Air/ Fuel mixture ratio and possibly supply an insufficient volume of fuel for a given burner design.
I assume your Tech when cleaning the burners would check the orifices also, but maybe not. Once the burners are removed an Oxy-Acetylene torch tip cleaning tool can be easily inserted into the orifices to clean them. The Oxy-Acetylene torch tip cleaning tool has a variety of wire sizes for different size orifices. Sometimes (if needed) you start with a smaller wire size and work up in wire size to the actual orifice size.
Working with an Oxy-Acetylene torch (especially a cutting torch) it is much more obvious when the tip plugs up. Slow dilapidation of a burner orifice is a much more subtle change.

1902Shingle

Thank you @109A_5, I think we found another tech to take a look, praying that he has more depth of knowledge to figure out our issue and I will definitely ask him to take a look at the orifices if he doesn't see anything else that is obvious.  I also did notice that the two burners to the far right are not actually producing flame like the others. 

109A_5

Hello @1902Shingle,
Yes, it looks to me like you need a Tech that will remove the burners (re-inspect them) and actually clean out the manifold orifices, not just look at them with a mirror, but actually clean them out.
If you want, you can get your own Oxy-Acetylene torch tip cleaning tool, Auto Parts stores, Welding Equipment vendor and even Amazon, they are not expensive.
Also the Tech really should do a Combustion Analysis when they are done.

1902Shingle

Ok, new diagnosis is leaks in our rails. He took everything apart rechecked all the burners and all ports and openings with a scope. Manifold pressure is normal so hes trying to find replacement parts but not very promising. If they can't find the parts I think I'm going to have someone else come out for a second opinion because at that point our only option is replacement. So we just continue to leave it off at the breaker and manually call it and monitor for ignition. Which will be fun when it's 10F next week. 

mattmia2

If it is leaking they will be able to show it to you with soap bubbles. Unless the tappings for the orifices are stripped or there is some sort of crack, it can be sealed with dope or teflon tape (teflon tape has to be used very carefully to keep it from getting inside).

109A_5

Hello @1902Shingle,
I assume by rails that is referring to the burners. I would think if it were leaking somewhere where it should not be there would be flames there (at the leaks) once it was all up and running.
The way your recent picture was of the flames being lower at the one burner my comfort level would be much better it they actually cleaned the orifice (actually all of them) and just not inspected them. I doubt the camera (scope) can see all the way back to the manifold, the tip cleaners are at least a few inches long and come in different lengths. What if the restriction is on the back side of the orifice.

1902Shingle

mattmia2 said:

Unless the tappings for the orifices are stripped or there is some sort of crack, it can be sealed with dope or teflon tape (teflon tape has to be used very carefully to keep it from getting inside).

The rail cam be sealed or the orifice?

109A_5

Hello @1902Shingle,
The orifice threads into the manifold. When the burners are removed the orifice stays on the manifold. If the orifices were to be removed for inspection the burners would have to be removed first to gain access. Since the boiler is older I would just clean the orifice and not risk damage by trying to remove it from the manifold.

The orifice focuses a stream of gas into the burner and causes air to be drawn in through the air shutters.
The Air/ Fuel mixture then passed through the passages of the burner assembly to be ignited and burned.