Steam boiler: flame goes on, off, back on

NewGuy

This happened several times last night until it didn't. Attached a video.

Brand new Crown boiler. I've posted elsewhere about a downdraft/spill switch problem that isn't fully resolved. After working fine for several days, the spill switch tripped last night. Reset and then this was happening every 3-4 minutes for about 1/2 hour. Then it worked ok.

About the spill switch. The problem mostly goes away when I crack open a window in the basement. The top suggestion was to insulate the exterior flue, followed by a warming fan. But this flue worked fine for 10 years, so before a 25k construction job, we are looking at the possibility of 1) too many turns in the flue coming out of the boiler, 2) too close to 6 water heaters, 3) dead air since the open windows helps. But even dead air would be unusual since, again, there was a functioning boiler with spill switch before.

Note that the old boiler exhaust faced the opposite side, outward, away from the water heaters and towards the back door and other windows. This also made the exhaust flue line more direct to the exterior wall.

Any advice is appreciated. Also looking for a reputable HVAC person to inspect this issue in Northern New Jersey and be sure about the very expensive insulation idea.

https://drive.google.com/file/d/113G5Ajyx0T7vPjJNcscV6-iTaJ3mybPS/view?usp=drivesdk

https://drive.google.com/file/d/113YF8ccjrAwv7aXgGfXoFxA68JVYfCcO/view?usp=drivesdk

EBEBRATT-Ed

In NJ PM @clammy or @EzzyT

Jamie Hall

This^^^. Some of the best in the business.

On the spill switch and window, though. It's trying to tell you something. Listen to it.

LRCCBJ

This guide might assist with determining if you actually have a draft problem:

https://forum.heatinghelp.com/discussion/106122/faulty-spill-switches

pedmec

Sounds like you might not have enough combustion air in the room. Did they install a fan in a can or is there an existing combustion ducts with dampers on an outside wall? Opening up a window is an indication of lack of combustion air and creating a negative in the room.

But that doesn't jive with the flame going out and restarting. Unless its causing the flame to fall off the flame sensor. You need a better pic. wide view so we can see the set up and if you do a video take one of the sight glass. wondering what low water cut off they are using.

pecmsg

For a new boiler there's a lot of crap laying in the bottom.

LRCCBJ

A couple of questions:

In the first video, when the boiler shutdown, how long had it been running?

In the first video, the boiler restarted almost immediately. Were you able to reset the spill switch that quickly?? It does not appear possible.

If the spill switch was at fault, it is highly unlikely that you could reset it that quickly. Its temperature would not have fallen sufficiently to achieve a reset.

NewGuy

No, the spill switch was not going out at this time. It had gone out earlier forbthe first time in a week. I had two failed restarts. Then I opened the window further and it worked, except for about 30 minutes of this flame on, flame off scene. Eventually, it ran smoothly all night. I do have a LL carbon monoxide detector at the basement opening to be safe. Nothing registered.

pecmsg

with the window closed something in the system that is shutting it off.
until that’s found keep the window open.

109A_5

Hello NewGuy,

You may have multiple issues. Did the 25k construction job tighten up the envelope of the house, as pedmec stated your available combustion air source may have been reduced. Is the quick shut down and restart due to pressure ? Is the boiler oversized. Is it surging (LWCO tripping) and needs skimming ? Does it have one of those goofy LWCO units that shuts it down every so often to verify the presence of the water ?

LRCCBJ

https://forum.heatinghelp.com/discussion/comment/1823148#Comment_1823148

The spill switch was not the culprit in the video as you agree.

However, based upon your description, it had gone out earlier due to the spill switch.

This would imply that you have TWO separate issues. I find this extremely doubtful and suggest that some data is lacking.

It would be beneficial if you could get an independent temperature measurement near the spill switch when you believe it tripped. I would not dismiss the possibility of a spill switch that is not properly calibrated.

Revenant

The original discussion on this issue from back in October:

https://forum.heatinghelp.com/discussion/198213/rollout-or-spill-switch-tripping-on-brand-new-boiler

@EdTheHeaterMan and @Bob Harper shared some very detailed knowledge then.

Your old boiler was inefficient and properly heated the chimney.

Your new boiler is more efficient and not heating the chimney enough.

You can thank the Department of Energy and the EPA.

Increasing efficiency beyond a certain point saves fuel and wastes money.

I call it the "Let Them Eat Cake Energy and Carbon Policy".

We live in a broken world.

109A_5

Looking at the other post, what is going on here ???

Bob Harper

A lot going on here. First of all, it must be properly installed. That means for the venting, it must be a listed liner, vent or chimney properly installed. The horizontal offset from the boiler to the chimney is stated in the code as is derating for elbows, which cause flow restriction. Each joint must have a minimum of 3 equidistantly spaced screws per joint. At this size, I believe the connector should be either 22 ga. galv. or 24 ga. ss. You have not provided any combustion analysis readings so everything is going to continue to be guesswork. A "spill switch" should be a manual reset. A flame rollout switch is typically a single use fusible link that would require replacement at each trip. On, off, on cycles are typically a problem with flame rectification. You can conduct simple systematic troubleshooting to rule that out: is the incoming power proper polarity 120vac RMS(108-132 vac),, peak voltage 153-185 vac, 60 cycle (<2volts neutral to ground) with less than 5% voltage drop, no bootleg grounds and low impedance conductors(< 0.0048 Ohms/ ft 14 ga./ 0.003 Ohms/ft. 12 ga./ <1 Ohms to protect people; < 0.25 Ohms to protect equipment. Must have surge suppression by code. Coming off the 24vac transformer L1 to Transformer Hot or TH terminal should be additive voltage for correct phasing. You should have a world class ground from flame rod to chassis. Where the burners are part of the ground, check for their contact and no corrosion. Need min. 4x the mass of the flame rod, which should be spotless and scrubbed every time you touch it or annually at min.

Measure your gas pressures: static inlet with everything else in the building off; just the boiler, full load everything firing concurrently; measure manifold pressure. If your inlet drops below min. or flutters, correct the gas piping. Check any MP regulators and venting; If the inlet gas is sufficient and stable, assess the manifold pressure- is it sufficient (determined by combustion analysis) and stable? Are all orifices correct, clear, properly engaged into the burner venturis? Is there anything near the boiler, such as objects or stray air currents that could adversely affect the free flow of air into the boiler cabinet and burner compartment? Air turbulence can disrupt the secondary air at an igniter causing loss of rectification on an otherwise perfectly firing appliance and controls.

Take your micromanometer and read the following: Note wind speed and direction. Do not test if > 10 mph. CAZ to outdoors via a basement window (Stack Effect). Try front vs. back sides; CAZ to first floor; CAZ to any adjacent space separated from the CAZ that could create a separate pressure zone. Now, starting at the front door, determine the Neutral Pressure Plane using a smoke puffer. Repeat at backside. If windy, try for upwind (windward) and downwind (leeward). If > 10 Pascals, stop test and wait for calmer wind. Locate the NPP. Now, survey the upstairs for air leaks. Check every window to ensure it is sealed. Same for attic stairs or hatch. Must be gasketed or seams taped. Any ceiling penetrations must be tight. All 'can' luminaires (ceiling lights) must be ICAT- Insulation Contact Air-Tight rated) if extend into attic. If any upper level leaks, repeat Stack Effect tests and note change. If the building continues to be very drafty, consider contacting an energy rater to guide weatherization with a blower door test. They can perform a Worst Case Depressurization Test if you feel overwhelmed. Otherwise, this may reveal some endogenous influence causing venting failure where there is nothing 'wrong' with the equipment or venting.

Measure your stack draft pressure at standby. Is there a flow reversal at standby? Do you have a cold backdraft? Compare your stack draft vs. your building Stack Effect. Who wins that tug of war? You want the NPP as low in the building as possible with the minimum Stack Effect.

Set up your DMM in series with the sensor to measure flame rectification in microamperes. Set up a video camera on the screen. Start recording 10 seconds, make a call for heat and record through a firing cycle. Have a second video on the burners recording flame patterns and your combustion analyzer running the whole time. Repeat at: call for heat-1 min; 5 min. 10 min.; 15 min.; open the switch; 5 min. post-purge. Lay the data over a timeline. Your problem should jump out at you.
Flame rectification requires a stable flame to conduct the signal and avoid dropout. A stable flame is a happy flame.

HTH,

Bob

BTW, if you need a chimney pro in North Joisey, contact Ryan & Sons in Landing, NJ or Bridgewater Chimney and tell them I sent you. Two of the best instructors in the country. Tell them I taught them and don't let kids hear their response.