Ignition problem
My neighbor's old gravity feed gas boiler has been running fine as long as I've known her.
A couple weeks ago the pilot went out. It would light and the boiler fire up again but go out after a minute or two (both pilot and main flames).
She has the thermocouple replaced, no improvement. Then she had the gas valve replaced with the same model (robertshaw). It worked for about 5 hours and then went out again. I dont think it's the thermostat because the pilot goes out as well.
She's had the same company (local plumbing) go out twice, each time with 2 different guys. After billing her 5 hours they can't figure it out.
Ideas? Thanks
Bryant 245-8, 430k btu, 2-pipe steam in a 1930s 6-unit 1-story apt building in the NM mountains. 26 radiators 3800sqf
Comments
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This is natural gas supply? Was the gas valve set up for NG or propane? Did they check the gas pressure at boiler ? Static pressure? dynamic pressure? I don't see a sediment trap in that piping? I wonder if the line is obstructed?
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what is the line pressure when it goes out? sounds like it might be a bad service regulator or something like that.
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That is beautiful. More info please. I assume the pic is the old gas valve, pic of the new?
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Boiler on a wood floor?
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is that piece of sheet metal in front of the combustion chamber supposed to be there?
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Restricted (contaminated) pilot orifice. Not enough pilot flame.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
if the pilot burner was clogged it would go out when it wasn't firing too.
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Been in that spot over 100 years, imagine that.
Bryant 245-8, 430k btu, 2-pipe steam in a 1930s 6-unit 1-story apt building in the NM mountains. 26 radiators 3800sqf
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I'll check it. Thanks
Bryant 245-8, 430k btu, 2-pipe steam in a 1930s 6-unit 1-story apt building in the NM mountains. 26 radiators 3800sqf
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The combustion chamber is actually above that, behind the area with the central metal circle. Has always been there. Tomorrow I'll try lighting it after removing that sheet.
Bryant 245-8, 430k btu, 2-pipe steam in a 1930s 6-unit 1-story apt building in the NM mountains. 26 radiators 3800sqf
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Natural. I'm assuming the techs she called knew that. Will have to find someone who can take those readings
Bryant 245-8, 430k btu, 2-pipe steam in a 1930s 6-unit 1-story apt building in the NM mountains. 26 radiators 3800sqf
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Did you check the millivolts on the thermocouple with the pilot lit? did they change the pilot assembly? sounds like the pilot flame might just be barely making contact due to dirty pilot assembly.
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Restricted / marginal, not totally clogged. Water in the gas main.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System1 -
I haven't. Initially I asked her to call licensed professionals since I'm not one. At this point I'll start the list in this thread the best I can.
Bryant 245-8, 430k btu, 2-pipe steam in a 1930s 6-unit 1-story apt building in the NM mountains. 26 radiators 3800sqf
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let's clarify this, does the pilot stay lit with the main burner off?
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It does not. When I light the pilot, the main burner turns on. While burning, the pilot goes out followed by the burner. About 2-3 minutes altogether
Bryant 245-8, 430k btu, 2-pipe steam in a 1930s 6-unit 1-story apt building in the NM mountains. 26 radiators 3800sqf
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I have not. Let's say it stays on. What does that say? Low gas pressure?
Bryant 245-8, 430k btu, 2-pipe steam in a 1930s 6-unit 1-story apt building in the NM mountains. 26 radiators 3800sqf
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gas supply or combustion air or maybe venting/draft
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Yes low gas pressure, or maybe a more realistic scenario, the pressure drops significantly at the boiler due to a supply restriction. That's why testing not guessing usually works best.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
I'd be curious about the inlet pressure during all modes of operation and when off.
https://www.pscia.com/ASSETS/DOCUMENTS/ITEMS/EN/1-489.pdf
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
So 4 guys, 5 hours, a thermocouple and a gas valve and no pressure testing ? That seems a bit pitiful to me. Parts cannon troubleshooting fails again.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
Yep. Same company that maintained the boiler in my apt building before I bought the place (It was a disaster). I give thanks for this forum everyday.
Heading over to light her pilot soon. Will report back.
Bryant 245-8, 430k btu, 2-pipe steam in a 1930s 6-unit 1-story apt building in the NM mountains. 26 radiators 3800sqf
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Here are pics showing the new gas valve and pilot, which I've just lit, thermostat off. Will see if it stays lit until tomorrow
Bryant 245-8, 430k btu, 2-pipe steam in a 1930s 6-unit 1-story apt building in the NM mountains. 26 radiators 3800sqf
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At less than $150 they were, relatively, cheap parts. I would have done the same. Now she has spares :).
Bryant 245-8, 430k btu, 2-pipe steam in a 1930s 6-unit 1-story apt building in the NM mountains. 26 radiators 3800sqf
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that combination valve alone is around $300-$500.
unless the draft from the main burner is moving the pilot burner the issue isn't the pilot burner being dirty.
those doors being the way they were when whoever replaced the valve adjusted the combustion is important to the combustion. They affect how much primary and secondary air the burner gets.
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Bryant 245-8, 430k btu, 2-pipe steam in a 1930s 6-unit 1-story apt building in the NM mountains. 26 radiators 3800sqf
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Glad to see the gas piping was fixed and sediment trap added in. Although having a flex gas pipe exposed in middle of kitchen/pantry is not exactly safe. HOpe you are able to figure this out.
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Ok, so the pilot goes out on it's own after a few minutes, thermostat off. I lit it again and, just for kicks, turned the thermostat on. The pilot went out as soon as the burners fired up.
The plumbers that installed the new control valve mangled up the, new, thermocouple pretty good. Would that affect it's performance?
Bryant 245-8, 430k btu, 2-pipe steam in a 1930s 6-unit 1-story apt building in the NM mountains. 26 radiators 3800sqf
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Yes that could definitely cause issues
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i'm surprised it works at all like that. that certainly would be the first thing i'd try although this doesn't explain why it was doing it with the old valve. does th pilot still go ou if you remove that piece of sheetmetal from the front of the conbustion chamber?
when the pilot goes out does the safety valve in the gas valve close first or does the pilot go out then the valve closes? you should hear the safety valve click when it closes.
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I was about to mention it, I'm glad to see you caught the mangled thermocouple, running it over with the service truck a few times then installing it is not best practice.
You may have multiple issues, I'd replace the thermocouple, see what it does, if it still acts up then measure the gas pressure at the inlet side of the gas valve in all modes and off.
Maybe the original issue was ONLY a bad thermocouple, they changed it with road kill, and then thought the gas valve was bad. Too much bad repair technique IMO.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System2 -
I tried everything, with and without the sheet combined with opening and closing the round vent (towards top of boiler). I think I heard the safety valve click once but definitely didn't the other 4 or 5 tries.
Bryant 245-8, 430k btu, 2-pipe steam in a 1930s 6-unit 1-story apt building in the NM mountains. 26 radiators 3800sqf
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I put in the new thermocouple myself before having her call the plumbers to try the new gas valve, it made no difference.
I was very careful not to kink it and definitely didn't touch the wire with pliers (as seen in original pic above).
Could new thermocouples be bad out of the box? I know it happens with even the best of parts (gorton, ahem, vents.)
At this point I'm thinking this:
- changed thermocouple, no change due to bad gas valve : no worky
- plumbers install new gas valve destroying new thermocouple: no worky
Tomorrow i'll try it with the original thermocouple and if that doesn't work then get another new one (they cost me $4 at ace) and see what happens
Bryant 245-8, 430k btu, 2-pipe steam in a 1930s 6-unit 1-story apt building in the NM mountains. 26 radiators 3800sqf
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if it doesn't click until after it goes out it is a gas supply or combustion air issue. if the thermocouple is failing to prove flame and closing the safety valve it will click then the flame will go out.
if the flame goes out then it clicks probably a few to several seconds late, the pilot flame is going out then the safety valve is closing because there is no pilot flame.
you can test the output of the thermocouple with a millivoltmeter.
if you leave the valve in the pilot position and keep the knob held down that does the same thing as the thermocouple. if you hold it down for however long it takes for the pilot to go out and it still goes out then it isn't the thermocouple.
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" Tomorrow i'll try it with the original thermocouple and if that doesn't work then get another new one (they cost me $4 at ace) and see what happens "
You can try the original thermocouple to see what it does, when it is all said and done I would have a new thermocouple installed since that should give the longest service life compared to a used one.
The plumber(s) should have never left that mangled thermocouple installed.
If it still seems to 'Run out of Gas' with other thermocouples check the gas pressure.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System1 -
Ok. I put the original thermocouple back in. It's turns on for a minute then the pilot goes out followed by the burner via the gas valve click. Video:
The pressure goes from 0.1 to 9.2 mbar when the burner kicks in..then back down to 0.1 when it's shut off
Bryant 245-8, 430k btu, 2-pipe steam in a 1930s 6-unit 1-story apt building in the NM mountains. 26 radiators 3800sqf
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What is the gas input side pressure of the gas valve doing ? Should be a test port there too.
If you continuously hold the knob in pilot lighting mode (position), will the pilot run indefinitely ? If so try a new thermocouple.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System1 -
on the supply, not the manifold
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Actually, don't see an input port...edit.. is it this?
Bryant 245-8, 430k btu, 2-pipe steam in a 1930s 6-unit 1-story apt building in the NM mountains. 26 radiators 3800sqf
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