Uneven Burn

I have a Harman Mark III. For some reason the past few weeks I can only get the stove to really burn in the front 2/3 of the stove. The back 1/3 sits there and doesn't burn. I have plenty of draft and I keep the ash pan emptied. Even if I keep the ash door opened to get the stove really fired up the back doesn't want to catch and go. Any ideas?
Tom

Hi Tom,
i have the same stove, and my first thought is maybe you
have some ash that won't clear out of your last
grate, and the fire can't get any draft back there...

when you shake, (with a good hot fire) are you getting a
nice glow in the ash pan, and a few hot coals coming down?

can you notice the reflection in a clean ashpan if you can
see that glow up under that rear most grate.?

Also, is there any chance that the last grate isn't shaking
with the other 2? I'v not had anything like this happen, but
can imagine something breaking and one grate not moving???

dutch wrote:I'v not had anything like this happen, but
can imagine something breaking and one grate not moving???

That was my initial thought too.....

I've seen the same problem in forum member Greg White's Harman SF150. His fire was not burning in the front of the firebox.

Using a mirror we were able to see all the grates moving/shaking correctly. So we made up a poker using a stiff wire, about 3/16" thick wire. Just a 4" long 90* bend on one end. Using the poker we worked up between and around the dead grate, and several handfulls of ash fell down into the pan. We shook the grates again, and another handful of ash fell down. This opened up the air passageway and the stove burns normal now.

The ash doesn't always burn to a fine powder, sometimes it is in the form of crusty, crumbly chunks. These chunks can be too big to get through the gaps in the grate, and can even avoid the grinding action of the grates when shook.

We used the wire from the frame of a 'political sign'. This wire frame was perfect to make the poker out of. A good use for the 'leftovers' of an election!!

I'm sure you will find the grate blocked, and once cleared the whole coal bed will burn.

Greg L

.

Thanks guys, I have a poker that has a 90 degree bend in it. I'll try clearing all the coal off of the back grate and see if I can't find some ash build-up.
Tom

i have the same stove...my problem lies towards the front on the edges,but only from time to time nothing serious.i take a rod about 16" and poke it from time to time and this loosens up the ash that is there and it shakes right out and i get a complete burn for about 3-4 days,then i do it again...only takes a few seconds and isnt that big a deal.i have a question for you fellow mark3 users,i just got this stove a month ago,i traded my tlc 2000 for it.do you guys run a hand damper or a baro on yours? i have a 18' ss liner in my chimney,6",i have a thermometer on my stovepipe about 10-12" above the elbow and it runs around 225-250,..i have notice some of you guys running cooler temps!

[quote="bugizedo you guys run a hand damper or a baro on yours? i have a 18' ss liner in my chimney,6",i have a thermometer on my stovepipe about 10-12" above the elbow and it runs around 225-250,..i have notice some of you guys running cooler temps![/quote]

Do you know what your draft is? If it is over .06 you could be burning more coal and getting less heat from it. MOST manufacturers equipment manuals state that a barometric damper is required with their units. Get an incline manometer too. It's worth the $30.

I have a barometric damper on mine and an incline manometer. I have my damper set up so I run a constant .05 for a draft, even when I have the stove at full open. I rarely see my temps go above 150, and thats when the stove is running so hot I can barely stand by it. Without it I think you'll be throwing heat up the chimney. Harman does say that you should have a barometric damper.
Tom

i have no idea what a manometer is where should i put the baro?...closer to the stove or closer to the chimney?i had one on a wood\oil furnace once,it was about halfway in between!

http://www.dwyer-inst.com/htdocs/pressu ... 0Price.cfm
You would want the model 25, you are looking for .05 for your draft I think was mentioned for your stove.

The baro usually goes towards the chimney if possible. The RC is a coal specific unit. A Tee makes the install very easy.
http://www.fieldcontrols.com/pdfs/02702600.PDF

hey guys...thx for your help