Carbon Monoxide Problem

I burn coal in a Harman Mark 3. Yesterday I came home to a fire that was nearly out and my carbon monoxide detectors were sounding their alarms. My ash pan was on the full side but otherwise I couldn't see any problems. I had my chimney cleaned earlier this year, so I don't think blockage is a problem. I have trouble buring coal on a warm day (above 50) but it was cold out when this occured. I am at the bottom of my coal bin and the coal may be of a different or mixed quality. Not sure if that matters. Any suggestions as to what the problem might be would be appreciated. (And this is a good reminder to check your detectors. I would never have known there was a problem; there was no smell in the house at all.) thanks!

aliceme wrote:Yesterday I came home to a fire that was nearly out

My guess, the fact that the stove was nearly out, was the problem. That will allow the chimney to cool and the draft will become minimal, and may even reverse. The positive side being, the same as the possible cause, .. "the fire was nearly out".

I would check all elbows and horizontal sections of pipe for ash build up.

I agvree with Dallas in guessing it was more of a draft problem than anything else. I used to have an old Dutchwest Federal that would give of CO with low burns. As soon as I would open the ash door & increase the fire/draft the CO went away.( By the same token, this is my 3rd year with a TLC-2000 & have never had any CO readings no matter how low the fire or draft.)
You know that CO is nothing to fool with. If you don't have one already, I suggest you get a digital readout type of CO detector so that you can see what the levels are & if they are rising or falling.

It's possible that a poor quality coal may have been responsible for your stove burning to a low fire, but not for the CO level inside the house. I agree that you should check all the elbows for ash build-up. The design of the baffle in the Mark series lends itself to high amounts of ash building up in the outlet of the stove where the first elbow would attach. I have a tee with a cap on one end installed at this point. I have let the stove go out and cleaned it 2 times this season, in addition to the cleaning before the first fire in the fall. The most recent time the tee was about half full of ash, and a reduction in draft was evident before the cleaning.
Better to let the stove go out and check for ash build-up in the pipes then to ignore it and wake up dead one day.

As previously mentioned, check your 90's and horizontal sections. We have a Mark III and I clean ours 3 - 4 times per year depending on the amount of coal used. When you clean make sure you vacuum off the top of the baffle inside the stove. The ash builds up in there also. I can usually tell when it is time to clean by the lack of draft when loading or starting up a fire.

Thanks to you all for your help. It was a clogged elbow which was causing a poor draft. Everything got a good cleaning and now the stove is working well.
thanks again.

Glad to hear it was an easy fix.
I don't know if you can do this on your installation, but a 'T' that is capped off instead of a 90* will make it much easier to clean out the ash. Watch the draft on the stove closely when loading and shaking down, I think you will be able to see a difference when the 90* starts getting clogged so you can tell when its cleaning time.
I can tell when shaking down that mine needs cleaning because some ash will puff out the ash pan door. Also when loading more smoke will come out the door than usual. Before doing each of these I will have the ash pan door open for about 5 minutes to get the coals going or it will happen a little even with a clean flue pipe.

That's correct, a tee makes things a lot easier, if you can install a tee with a cap on one end cleaning out fly ash is a quick task.