Heat N Glo Northstar producing Carbon Monoxide

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Bcurley

Member
Nov 11, 2014
27
Long Island, NY
Hi all, I need some brainstorming on this one...

I am on my 5th season of burning the Northstar with no issues until now. This past Friday (11/8) was my first burn of the season. I burned 2 loads and went to bed. The fire was about half way through its burn when I went to sleep. About 4:30am my family was woken up by the carbon monoxide detectors going off. I immediately evacuated and called the fire dept. They came in and confirmed the CO in the house. Before evacuating the house I distinctly remember turning off the fan to the fireplace. The fire dept went throughout the house and the highest levels were coming from upstairs. We all assumed it was the gas furnace in the attic. I had an HVAC guy at my house to check everything out and all looked good. I wasn't using my furnaces during the day as we thought that was the issue and I continued to use the fireplace. Later in the day I was able to get a handheld carbon monoxide detector and went throughout the house with it and all levels were zero. We made sure to turn on the heat to the house and tested all equipment and everything came up negative.

Saturday night we all went to bed and I kept all furnaces off and had the fire going. Again at 5:30am this morning the carbon monoxide detectors went off. I evacuate again and grab the handheld and start to chase the highest levels. First went to the attic and the levels dropped. Next went downstairs and levels started to climb. Went into the room where the fireplace is and the the levels spiked to 250ppm. I immediately shut the fan to the fireplace off and the levels started to drop right away. I am trained on how to use these meters as I am a hazmat technician in my law enforcement job. I vent the house out and 20 minutes later all is good. The fireplace is 100% the culprit of the carbon monoxide. It is only happening when it gets to the smoldering stage of the fire as both nights were after about 12 hours from last start of the fire.

I checked the chimney this past spring and it was clean as I burned well seasoned wood mixed with envi blocks all season. I plan on sweeping the chimney regardless of how it looks and replacing the baffle board and ceramic blanket. Besides cleaning the inside of the box last week and replacing the ACC timer I haven't done anything else to the fireplace.

Does anyone have any thoughts as to what may be causing this and how to prevent it? This is a life threatening problem and needs to be remedied!! I plan on calling HHT on Monday as well. Thanks for any input.
 

begreen

Mooderator
Staff member
Nov 18, 2005
98,081
South Puget Sound, WA
Sounds like draft is insufficient and possibly reversing. The easiest first place to check is the chimney, especially the chimney cap screen if there is one.

Where is the fireplace located, main floor or basement? Does the fireplace have an outside air supply? If so, check that the intake screen is clear.
 
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Bcurley

Member
Nov 11, 2014
27
Long Island, NY
Sounds like draft is insufficient and possibly reversing. The easiest first place to check is the chimney, especially the chimney cap screen if there is one.

Where is the fireplace located, main floor or basement? Does the fireplace have an outside air supply? If so, check that the intake screen is clear.

‘The fireplace is located on the main floor and it does have an outside air supply. I will be checking the chimney tomorrow. The cap on the chimney is intact, so I doubt ther was anything in there. I was thinking same about insufficient draft, but the fire was working well all day and this was only happening at the smoldering stage.
 

tommyH

New Member
Nov 10, 2019
15
Alabama
I have nothing to suggest for you except maybe the gasket(s) need changing. But....Thank goodness we have CO detectors.
 
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bholler

Chimney sweep
Staff member
Jan 14, 2014
31,145
central pa
‘The fireplace is located on the main floor and it does have an outside air supply. I will be checking the chimney tomorrow. The cap on the chimney is intact, so I doubt ther was anything in there. I was thinking same about insufficient draft, but the fire was working well all day and this was only happening at the smoldering stage.
That is when draft is the weakest. And when high concentrations of Co are produced
 

moresnow

Minister of Fire
Jan 13, 2015
2,157
Iowa

Bcurley

Member
Nov 11, 2014
27
Long Island, NY

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moresnow

Minister of Fire
Jan 13, 2015
2,157
Iowa
This is the cap I have. It is free of any creosote on it.

If its truly clean your good to go. That cap looks very susceptible to buildup on the inside. My opinion only. Not saying its dirty inside but have you popped it off for a visual since these troubles started? Possibly worth a peek. Good luck.
 

David.Ervin

Feeling the Heat
Jan 17, 2014
297
O-H
I've got the same fireplace and same cap. I hate that cap. It plugs up with creosote like nothing else and it's a bear to clean. It's also HUGE for no obvious reason, which makes taking it down for a scrub a real pain. Mine's also starting to corrode badly, so I'm aiming to replace it with something less awful next year when I go up to clean it. I'm open to suggestions.
 
This happened with my Northstar last night. Woke up at 430a to CO alarm going off @18ppm. I have a couple detectors in various places all with PPM readouts, one is more expensive than the others and reads accurately to low amounts and will also alarm before the US mandated 70PPM for 10mins level. This one alarms somewhat softly every 10s when it detects >15ppm for 15mins IIRC. It did get as high as 27ppm according to the peak readout. It would alarm continuously at the US mandated 70ppm/10mins level.
I took the CO detector off the wall and walked around, definitely emminating from the fireplace area. Nothing else was running anyway, no stove, furnace was off , hot water was not running.
That sensitive one never read above 0 unless I put it right above my ash bucket with some coals in it which I do just to test it reads anything.
But I was very puzzled as to why. My northstar is 13 years old and has a 28' stack and I've never had draft issues even on "warmer" days like 42ish degrees. Cap's clean, chimney and cap cleaned every year even though it doesn't ever seem to need it, I burn usually only very seasoned (2+years) wood.
I was making an inspection...and....it dawned on me....., I forgot to open my OAK. The Northstar has a blockoff plate on a knob so you can seal the OAK when not in use so you don't get cold drafts coming in thru there and out your bottom grille as the oak on the northstar just connects into the bottom of the fireplace enclosure (not the firebox itself), basically it connects right to the inside of your house.
I started burning two nights ago when it was high 30 and low 21. First night wasn't a problem it was 21 outside. Next day was a slow rise all day to 30 outside, loaded up for the night and went to bed. The outside temp rose to 39f and the wind picked up big time. I guess without the OAK AND the fire on coals only at that time there wasn't enough air or temp differential to create a good draft and with the wind... back into the house it comes.
I'm not positive that was it, but I'd bet money it was. I'll know when I burn next probably this weekend.
First time I've ever done that. Glad I have the sensitive detector so you can diagnose the issue, at 18-27ppm that's safe to be in for 8hr/day so says OSHA..not that I accept that I want 0ppm in the house! The ones that don't alarm until you basically have to get out are kinda bad for that IMHO.
 
Yep, definitely was the OAK being closed. Been burning since Thursday night with the low level CO detector right out in front of the fireplace and nothing, meter has read 0 the whole time.
Don't forget to open that OAK! 🙃
 

clancey

Minister of Fire
Feb 26, 2021
2,441
Colorado
So glad you solved that problem--what does OAK mean? Tried to look it up but could not find what the abbreviation means--new at this----you people with all the abbreviations make people like me (new learners here) not know what you are actually talking about..after awhile it gets old especially when you cannot find the meaning from another source as stupid as this may sound to you..This is my grip of this day...old clancey
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
31,145
central pa
So glad you solved that problem--what does OAK mean? Tried to look it up but could not find what the abbreviation means--new at this----you people with all the abbreviations make people like me (new learners here) not know what you are actually talking about..after awhile it gets old especially when you cannot find the meaning from another source as stupid as this may sound to you..This is my grip of this day...old clancey
Outside air kit
 
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So glad you solved that problem--what does OAK mean? Tried to look it up but could not find what the abbreviation means--new at this----you people with all the abbreviations make people like me (new learners here) not know what you are actually talking about..after awhile it gets old especially when you cannot find the meaning from another source as stupid as this may sound to you..This is my grip of this day...old clancey
As bholler said, OAK=Outside Air Kit. Some stoves/fireplaces it's optional, on my zero clearance North Star Model, it's mandatory. It provides a source of outside air for combustion straight into the unit so you not sucking house air for your fire. In my case, when the fire was in coaling stage it doesn't have the draft potential a roaring fire does (a roaring fire will pull air from any crack in the house, also could overwhelm a furnace vent or range vent and cause CO from those sources), but in the coaling stage there's not enough difference to create a draft and when the wind picked up it blew it all back into the house through the air control. Coaling stage is also when the most CO is created from a fire.
My OAK has a open close feature on a knob so you can close it when the unit is not in use to keep cold air out. I had forgotten to open it. ;em
I always thought it was a not really nessesary saftey feature for those with poor draft or improperly installed chimney installs or whatever....but apparently it is necessary!
 
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