Can You help Solve this pilot flame going out Mystery?

Joseph_4

Hi to all,
I've been troubleshooting a No Heat call and have been there everyday this week. The boiler is an older burnham series 2 standing pilot. Got call with no heat where boiler lights up for say 20 minutes then goes out. Thermocouple was changed Saturday Night. got there sunday morning adjusted so tip being properly enveloped and putting out 24-26 volts dc. still going out , Changed with new Honeywell Vr8200 valve. still having same problem.. noticed argo board flickering on and off. but boiler still works properly for 20 minutes at a time. transformer on boiler putting out 27 volts. Thinking board may be causing short to somehow make pilot drop out (evethough we know pilot gets its dc volts from pilot flame itself and not house electric) I light pilot. and leave power off to boiler. and wallah pilot finally stays on for hours without going off). so I rewire boiler to bypass Argo Board. Turn on power. starts to go off every 20 minutes. thinking maybe whole boiler line has short. Rewire to different Breaker still goes off. Bottom line When electric on pilot goes off every 20 minutes. no house electric, pilot stays on whole night.

I have watched flame for 20 minutes dont see and water dripping( cuz of possible hole) putting out. There is no downdraft. And I dont see anything falling on area of pilot that could physically be knocking out. in my mind its electrical problem. But i dont know what.
Any Ideas?
Joe
HHI Services LLC

ratio

Has there been any electric work done lately, or line work outside maybe? Check polarity on the power (hot vs neutral), from the pole to the boiler. The two systems (pilot thermocouple & mains power) are never connected —except at the ground, which is (should be) connected to the neutral at only one point, in the 1^st means of disconnect. Also check the ground & neutral, maybe there's a bad joint that's allowing the ground to float & cause stray current to flow.

Assuming it is actually an electrical issue and not just an amazing coincidence.

Good luck, these kind of mysterious faults can really make you pull your hair out!

STEAM DOCTOR

Fill boiler to header. See if you get a leak

STEAM DOCTOR

Series 2=water boiler. My bad

STEAM DOCTOR

Is it possible that there is some sort of power surge? Dont know how that would cause pilot to go out.

STEAM DOCTOR

Maybe try to leave electric on but leave the 8200 turned to pilot setting. Grasping at straws. Agree with @ratio. These are the jobs that can make you turn grey

Bob Gagnon plumbing and heating

I had the same problem on a new install once, drove me crazy for a while, it ended up being a couple of drops of water in the pilot tube, the flame looked fine but once in a while it would be enough to put out the pilot, let us know what happens...

Thanks, Bob Gagnon

MechAcc

Are you monitoring input and burner manifold pressure simultaneously to see if there is a gas pressure drop?

STEAM DOCTOR

Make sure that the thermocouple is sitting properly in the pilot flame. I've had cases where the bracket was slightly bent so the thermocouple was getting some heat from the pilot but not quite enough. Don't we all hate these intermittent problems

plumbob44

Is a connected to a nest t-stat? I've seen those things do weird stuff that will leave you scratching your head

HomerJSmith

A thermocouple should output at about 30 millivolts, so it looks like you are good at 26 millivolts. 27 V for an idle transformer is about right.

So, as I understand it, you are losing your pilot flame and the gas valve shuts down the boiler burners? You are correct in that the pilot circuit is isolated from the 24V circuit. The pilot circuit is the thermocouple and an electo-magnet in the gas valve, that's it. As long as there is a pilot flame the thermocouple will generate the voltage to keep the electo-magnet holding the pilot (secondary) valve open. So, what's happening to the gas that lites the healthy flame on the thermocouple?

The burner flames look ok? What happens is that the burner flames operate until the boiler water reaches it's operating limit (180 deg) and then the aquastat (does it have dual limit?) shuts off the the power to the gas valve's main (primary) valve and the boiler burners shut down while the aquastat goes thru the differential. The pilot flame remains lit at this time. The pilot flame re-lites the burners when the differential is met.

If the pilot extinguishes itself at what point in the cycle does it go out? Before reaching operating limit, reaching operating limit and the burners go out, or on an attempt at re-lite after the differential is met?

I would check incoming and outgoing gas pressures on the valve when the burners are lit.

Fred

Does the pilot go out when a gas water heater or other gas appliance kicks on? Maybe incoming gas pressure??

HomerJSmith

If this boiler has been out of service for some time, like in the summer, some times spiders, for some reason God know, like to crawl into the pilot tube and make a web. I would remove the pilot assembly and remove the tube and push out the pilot orifice and take a fine needle and clean the hole in the orifice. You can get what looks like a healthy flame and it is not. The orifice can be partly plugged.

Every problem has a cause and every problem has a solution. It is lack of understanding that prevents a solution.

Joseph_4

Thanks for all the comments. I made sure thermocouple was in bracket at proper height . The 24 dc volts shows that.No nest tstat. I was there again with Rick of Burnham on phone for close to an hour and 10 minutes on the. He tried many tests thinking maybe the coil in the R8285D was weak but giving enough power on start up. we saw it hit high limit and drop out, but we also saw it stay on and cycle on again. I asked if any electric work done lately. Ans was no. I agree with Ratio I'm up to pull out hair. Jumped out flame roll out. still goes out after 20 min. Final outcome was to change everything to spark ignition. Rick said this is the best option if we are up to changing rest of controls and wiring harnesses
thanks
Joe

lchmb

curious..was it dropping the pilot the same time the burner shut down at limit?

HomerJSmith

Answer more of the questions. Re doing spark ignition is an expensive waste, it seems to me and a last resort. I would check the pilot orifice and clean it and look at the sequence of operation as to when the problem occurs.

Rick of Burnham and others are all looking at the 24V sys when you say it is the millivolt sys. You're hearing hoof beats and thinking Zebras. It's all about when the pilot goes out. If it stays on, then look at the 24V sys.

Pull you hair out after you clean the pilot orifice.

Bob Harper

You need to perform combustion analysis and not rely on just saying "there is no downdraft". Venting failure is a common cause of this. As CO2 backs up into the CAZ, it displaces O2, which leads to exactly what you have described. I find multiple new TCs lying on top of the water heater or boiler only to find a blocked flue. Even if this isn't the cause it must be ruled out FIRST before throwing parts at the problem.

HomerJSmith

A blocked flue vent or blocked flue would lead to spillage out of the draft hood unless the blockage occurs before the draft hood. It would trip the blocked flue sensor, I think it has one, or the rollout switch.

You wouldn't have 20 min of operation with a blocked flue, I would think.

Clean the damn pilot orifice with a fine needle.

ratio

Check the pilot, it's easy. Check the flue, it's important. But he said breaker off = pilot stays lit. It could still be coincidence, but...

I don't believe in coincidence. I do, however, jump to conclusions from time to time. Check everything that you haven't checked yet, then go back & recheck the things you already checked.

Bob Harper

Homer, allow me to assure you spillage out of draft hoods and combustion chambers is anything but predictable and does not have to spill right where someone located a spill switch, nor do such switches guarantee against spillage. You can also get massive spillage through gaps between vent connector pipe sections and especially where it enters the breeching. This is why combustion analysis by someone certified to do it is so important.

JUGHNE

It seems that the only way the electricity could knock out the pilot is by it turning on the main gas valve 24 VAC and then turning it off after a 20 minute burn cycle. When MV off it could change the gas pressure enough to knock out the pilot. Or when it lit it knocked out the pilot and then relit it from the main burner.

As MechAcc said above, need to monitor gas pressure on each side of the MV during operation of MV on and MV off.

I don't think a T-couple on a standing pilot knows about any electricity except its own. It just lives in its own little world. IMO

I would be suspicious of the pressure regulator for that boiler or the main one for the house.

Steamhead

HomerJSmith said:

Re doing spark ignition is an expensive waste, it seems to me and a last resort.

Well, it does do away with thermocouples and pilot outages. And, if the flame is lost for whatever reason, spark ignition shuts the gas down in about a second. The standard thermocouple setup can take up to three minutes to shut down. So spark ignition is safer. And the latest ignition modules have self-diagnostics built in, which can help keep us from pulling our hair out- assuming we still have hair

HomerJSmith

Steamhead, all my customers are poor folks. That provides a solution without understanding the cause. Forgive me, I always want to know why something fails. I learn something then.

In the early '90', I had a bunch of Honeywell zone valves fail. They have a year warranty and they failed at 1 yr and 1 mo. It always happens that way, so it seems. I took one apart to see why it failed. I had a pile of winding wire on the floor and gear pieces on the bench. I finally figured it out. The top bearing drop down and the rotor poled out. I confronted Honeywell and after going up the ladder a few rung, they admitted that they had a problem with some of the valve and sent me new replacements.

"Occam's razor... is the problem-solving principle that, when presented with competing hypothetical answers to a problem, one should select the one that makes the fewest assumptions."--Wikipedia. In other word the simplest solution is probably the correct one.

I would be really happy if you checked the pilot orifice hole with a fine needle and confirmed that it was ok.

lchmb

I have seen a number of these systems shut down hard and blow the pilot out on LP. I have also seen a number of them over the years where someone changed the pilot and did not size the orifice correctly (id suggest replacing it after checking for the proper size). It could also be the pilot is striking to far down the thermocouple while it is running.. are you monitoring the mv with the unit running?

DZoro

@Joseph You mentioned only time it does so is when power is supplied to the system. Were you able to confirm no power on neutral and ground? Power seems to be the common problem when this happens. Possibly run a separate ground to your burners/ valve. Change out the r8285, just curious are there any sequencers in the system?

JUGHNE

I lean towards Ichmb's theory of MV shut down.
The common problem is the burner shutting down after 20 minutes of operation.

You could start the burner let it run maybe 10 minutes, then shut the MV off by powering down and seeing what the pilot does. Or a 10 minute burn and switch the gas valve to pilot only if it has that feature.

DenverBoilerGuy

I'll bet it's a bad gas meter regulator.

HomerJSmith

DenverBoilerGuy, that why you put a pressure gauge on the input and output of the gas valve and watch what's happenin.

Of course, nobody's done that.

Joseph--There are question on this post that haven't been answered.

HomerJSmith

Dzoro, When there isn't any 120V to the boiler, it won't effect the pilot. The pilot circuit is separate from the 24V-120V circuit. When there is 120V supplied to the boiler it will go to lite on of the burners. The problem is in the lite on or shut down.

Keep the 120V power on and turn the gas knob to pilot and I'm willing to bet you the pilot stays lit, forever.

I don't think Joseph has a strong enough pilot flame, regardless of having 26Vdc. The pilot flame has two functions--provide electrical energy to keep the pilot valve open and to light the burners. Hey, I got an idea, maybe it has something to do with the pilot flame? Naw!

Joseph_4

Let me give you guys a little more info. I have watched main burner go off and pilot still stay on for about 30 seconds and only then go out. (meaning the big whoosh of the main flame is not turning it off cuz that would happen immediately) I have watched main burner go off and pilot to continue to stay on until diffrential met and go back on. I have seen it go off after 2 minutes of main flame shut down. It is not consistent. The boiler was attended to the day after it when out and the whole pilot bracket assembly was also replaced. so no water or spider webs.
Honeywell had no answer for me either. I have been there 6 days in a row and haven't charged yet past an initial 165 service visit which I have way exhausted by giving new gas valve new thermocouple. sending my guys there twice. It has been me all the other times. All I want is a solution and no one seems to have it. I have spent personally about 4-5 hours in the house watching and doing work. If it was a laboratory to sit by her house all day and ignore all my other customers that would be pristine but its not the case. So far I'm losing my pants on this job cuz i care to help. Rick of Burnham's solution will make pilot relight on its own if goes out. I WILL at this point be telling customer before ordering parts that there will be a charge whether it works or not.. BTW I have always liked standing pilot more than spark (cuz personally i see less problems with standing pilot) but the customer will get back the "wasted money" by saving 84 bucks a year on doing away with standing pilot. There is no back draft whatsover and I have watched it just drop out while sitting there with no change in draft.
I am thinking of changing r8285d cuz what else is there to provide power.
thanks
Joe

Joseph_4

And to HomerJSmith.. this lady happens to be a single mom. someone else hired me and is footing the bill so it complicates it. I have been trying to charge as little as possible. I certainly have been trying to figure out the cause for 6 days not to be a parts changer. At the end of the day if I have seen the pilot stay on after limit shut down till lights up again the problem is intermittent
thx
ps Bob what is a CAZ .. Also what would it prove if fire of thermocouple stays on when I leave on pilot with power on?
Joe

lchmb

one question. the pilot is dropping out as in gas valve is closing? Or fire is going out and gas valve drops out after a period of time?

lchmb

as far as the power question..I think he's trying to figure out if you have an electrical short causing the gas valve to drop out.. in theory it would seem plausible..I've never seen one though..

HomerJSmith

Joseph, that's enlightening, that information should have been forthcoming, never the less, you're a good man for what you're doing.

Is there any lifting of the burner or pilot flames?

Did you check the input and output pressure of the gas valve when this happens? You need to do that. You may have a pressure drop out caused by the meter regulator. No sno on the regulator, correct? Any other gas appliances?

Disconnect the ignition board wiring from the gas valve and take a 24Vac transformer and connect it to the gas valve and with the pilot operating and plug the transformer into 120V and watch what happens. Then disconnect the power to the transformer which cut the power to the gas valve. If the same condition occurs, it isn't the board. Make sure that the boiler is plugged into 120V and thermostat is calling for heat and the boiler pump is operating.

JUGHNE

So what is the gas pressure before and after the gas valve?
And how much does it fluctuate during light off and shut down?
And also any changes when any other appliances come on?

I have spun my wheels many times before checking that very simple but important factor.

A sticking regulator can do some pretty strange things.

Joseph_4

Here's to a better ending. Armed with everyones input HomerJsmith, Jughne, Ichmb, Denver Boiler Guy, Ratio and anyone else. I went there with a new gas valve and r8285d and an ata140 transformer last night late to sit this one through and the idea of "check and recheck" First I rethought if always goes out after 20 minutes, must be pilot drops out after aquastat satisfies and goes out. Sure enough 4 times in a row I witnessed it last night. However each time the pilot flame usually stayed on for about 90 seconds after mv shutdown. Never all went out at once. I finally noticed that the tips of the pilot were yellow though not blue. (then I thought to what Homerjsmith said that pilot must be weak) Upon light up the pilot was a strong blue all around. [ Some anomalies were also that I tested mid cycle to shut boiler service switch to emulate an aquastat limit, and pilot flame strong blue all around, why wouldn't it become yellow} To answer this and Maybe.....

There is an important point that some of you guys mentioned that I'm still unclear about. In my world the thermocouple flame hits 2 dissimilar metals at tip which produces the 30 mv dc to keep pilot on when held down. It knows nothing about house electric. Rick from Burnham a New England Regional trainer with 35 yrs experience told me that once there is a call for heat the safety circuit is what is powering the thermocouple. I never heard such a thing and am still a bit skeptical. I am not an engineer. ( what happens then when you shut power switch..why does thermocouple./pilot stay on.. Is it like handing over a baton?

In this case only when I let aquastat shut down MV, did pilot flame get weaker with yellow tips and then cut out out after 2 minutes, but if I shut power switch pilot flame all strong and blue and wouldn't cut out. Why would this be, unless Rick is somewhat correct and safety circuit still involved and therefore not opening diagphram enough for pilot.

I Changed with another gas valve, blue all around at all times. Had do be bad regulator in gas valve like you guys were saying. For the first time in 7 days she woke up to a warm house.

I'm curious though if the slight difference in strength to pilot would have shown up on one of the ports on gas valve with my manometer since they test pressure to all gas in and all gas to manifold. not just the pilot.

Thanks to all for giving of your valuable time
Kudos to Dan and Erin for having this awesome site!
Joe
HHI Services

HomerJSmith

"Rick from Burnham...with 35 yrs experience told me that once there is a call for heat the safety circuit is what is powering the thermocouple." That would be nonsensical as the thermocouple isn't powered, it's a power source. It would be the pilot valve (electromagnet) that the safety circuit is powering, if it were true.

I have taken gas valves apart and that's not my understanding of how a gas valve works. Did this gas valve have an ECO (energy cut out) connector?

What was the new gas valve # that replaced the new gas valve that replaced the old gas valve. just curious.

ratio

Is it a thermocouple, or a millivolt generator? With a millivolt system, the generator runs the whole valve, you fire the burner with dry contacts. With a thermocouple system, the thermocouple holds a safety solenoid valve open all the time (that the thermocouple is generating power, i.e. hot), which allows gas to enter the pilot system and the burner solenoid valve. The burner solenoid is operated by an applied voltage of (commonly) 24 VAC or 120 VAC. if the pilot is not lit (safety valve closed) the position of the main valve is immaterial.

Joseph_4

its a thermocouple not a thermopile system. used a VR8300A before was VR8200A. No ECO connector . But how else do we understand that only when the aquastat shut MV then pilot got yellow tips was obviously weak and aventually ,would drop out in 90 seconds but if mid cycle id manually shut power on wall, Pilot would remain blue and strong and stay on. This leads me to believe Thermocouple is getting some power after a call from heat from safety circuit.
Thanks
Joe

ratio

One side of the gas valve thermocouple is inherently connected to ground due to the body of the gas valve being grounded through the gas train & boiler body, which by Code should be grounded. Other than this connection, it's exceedingly unlikely that the thermocouple could be damaged in a way that allows it to become energized via line voltage; hence my suspicion of a ground &| neutral fault.

But the fact that it went away (or seemed to!) when you changed the valve points to the problem being in the valve. An intermittent, progressive failure of the gas valve.

lchmb

Kudos to you for sticking with this one and doing it right..most would have walked away long ago and told them to replace it all... Good job!!