Bottom Glow Issues

[quote="cheechblu"]Yes. One is the primary going right up the chimney,and the lower one is just below the grates and above the ash pit. That is a secondary heat exchange pipe. Supposed to keep too much heat from flying up the chimney.[/quote]

Hi cheechblu, it appears that your primary flu is capped in the fire box, I would remove the cap, this is needed to liven up the fire before reload and shake. When the time comes to reload I would open your under fire air vents and turn the damper on your primary flu to OPEN, or as some of us call it "direct." When the coals are at it's peak, (this is a perception issue), throw a pail of coal on and let it catch with some over fire air to in order to gas off. When this layer has caught now you can shake, and then add a second layer of coal and allow that to catch. When you have loaded the desired amount of coal and all is well, switch the external flu damper to indirect and adjust you air inlets accordingly. With the Furnace in direct draft more air is sucked in and under the coals and the chance of you fire going out is much less! Do You have thermometers and a Manometer?
When I load my stove I wait until I get a temp. of 450 on top of the stove before I put it in indirect draft. Good luck.

Mike.

Thanks Mike. I will purchase manometer this week, and gauge top of stove to 450. I will let you know how this all goes.

I think you are OK with the hollow door. It looks like a good design to pre-heat the incoming air for a WOOD fire, but as we have said you don’t want much air coming from the load door for an anthracite fire. As long as the air inlets can be closed fairly snugly, I don’t think the load door is the source of your coal problems.

I am very uncertain about the two flue gas outlet ports. IS IT A WIDE OPEN PIPE FROM THE BOTTOM PORT TO THE CHIMNEY? The top outlet appears to have a damper. That would make sense for a wood fire, where you would open the damper to get the wood burning well, then close it to force the burn to a downdraft pattern. In other words, with an established wood fire combustion air would come in through the load door, and at least some of the flue gases would pass downward through the grates and exit via the bottom port. https://www.hearth.com/talk/wiki/downdraft-stove-operation/

I’m not sure you can get anthracite to burn in this downdraft pattern, at least not in this furnace. Most stoves burn the coal from the bottom up, not from the top down. Combustion air for anthracite should come in through the ash pit inlet, below the grates, and its ONLY way out should be by passing upward through the grates and through the coal, and exit via the top port. NOTHING at all should be able to exit via the bottom port when burning anthracite.

So I suggest you try this:
Open the damper for the top flue port and keep it open.
Stuff fiberglass insulation into the bottom flue port to block it completely. (Easy enough to remove later if you want to go back to wood.)
Keep the load door air inlets completely closed, or almost completely.
Control the fire by how much you open the ash pit inlet below the grates.

yep... im with rberg on this, Id seriously look at that connecting rear pipe (how are stopping draft from that lower pipe!!! YOUR NOT (even with the damper up top open! Mahhahahaah.... this is not going to BURN coal like that opposing/fighting drafts common guys wake UP! I bet that rear pipe is simply an open pipe (not original to the furnace), it most likely had a GREAT PLAN! but that damper needs to be able to block of the lower pipe 100%, the secondary upper door air should be block 100% since it has internal secondary air for coal burning... GG rberg

Its gotta be something wrong with that rear pipe not configuring draft correctly or as designed.

If I understand this correctly the furnace is set up to burn wood.

When you start a fire or add wood, you open the damper and this lets the exhaust go straight up the chimney. Then when the fire is burning good you close the damper and this forces the exhaust to go down through the hot coals on the bottom and this burns the fuel more compleatly.

This is not the best setup for hard coal, however it might burn soft coal well provided the draft is strong enough.

For hard coal you will need to remove the bottom "T" and cap the collor on the stove, then you will need to cap or plug the bottom of the top "T". That way the underfire air cant bypass the fuel bed and go up the chimney.

Dear rberg and dcrane,

Upon further inspection, as you can see from photo, the bottom 2nd exchange flue is right behind the bricks to the rear of the firebox. There are some gaps. I don't know if this is designed to block the air coming up to the grates, or if I should insulate around any gaps that I find in the area.
Any advice is helpful. Thanks.

I would be totally shocked if you found that lower flue open to the ash pan area. Would be easy enough to find out though, remove the pipe from the furnace pull a couple firebrick and put a light in the stove. Then look into the pipe on the back of the furnace.
I'm betting you have a U-channel welded to the back of the firebox that connects the upper and bottom flue only. Kinda like the design of a baseburner parlor stove.

cheechblu wrote:Yes. One is the primary going right up the chimney,and the lower one is just below the grates and above the ash pit. That is a secondary heat exchange pipe. Supposed to keep too much heat from flying up the chimney.

cheechblu wrote:Upon further inspection, as you can see from photo, the bottom 2nd exchange flue is right behind the bricks to the rear of the firebox.

SWPaDon wrote: I'm betting you have a U-channel welded to the back of the firebox that connects the upper and bottom flue only. Kinda like the design of a baseburner parlor stove.

What SWPaDon says makes sense. I can’t really tell from the photo – that’s what you need to find out. If you DO find the channel, make sure it is not plugged with soot and ashes. I had a wood stove once with heat-exchange channels along the back which were completely plugged.

The bottom line is, the combustion air must come from under the grates, and the flue gases must exit the firebox above the fire – though the gases might be drawn down and then up to the chimney once they leave the firebox, to make a longer path to radiate more heat.

P.S. If you can't tear into the furnace right now, you could try running it with the upper flue damper open rather than shut. That might be less efficient, but if the coal fire doesn't die out like you have been experiencing that will tell you something. If the upper flue damper is fairly tight, AND if there is a u-channel AND if it is plugged, then closing the damper would greatly reduce airflow through the fire and could explain the die-outs.

cheechblu wrote:Dear rberg and dcrane,

Upon further inspection, as you can see from photo, the bottom 2nd exchange flue is right behind the bricks to the rear of the firebox. There are some gaps. I don't know if this is designed to block the air coming up to the grates, or if I should insulate around any gaps that I find in the area.
Any advice is helpful. Thanks.

I would guess Don and Rberg are both on the right track, The furnace is clearly designed with some similar attributes of a baseburner for coal (or more specifically an indirect rear pipe used on many baseburners... your indirect rear pipe happens to be inside the furnace behind that rear wall). as I said before, I believe something is causing the draft to fight below & above the coal bed (which would explain the miserable burn your achieving), This could be caused by a few possibilities but if I had guess I would say their is a breech low in the furnace that is allowing draft to "pull" from below the coal bed. Even when you have that upper damper open this breech would still have "some degree" of pull and if you close that upper damper the pull would be much more. Either way... you DO NOT want this draft or "pull" to be "pulling" from beneath the coal bed (as Don mentions check internal channels behind that rear wall to see if clogged because it is critical when the stove upper damper is closed that the "pull" still comes from OVER the coal bed and down the rear internal chamber/channels and then out the lower flu pipe)... if that all clogged up behind their this "pull" will then be coming from wherever else it can! which means from gaps in firebrick and from below the coal bed.

I know im horrible at describing things in words but most the people here who know me understand what im trying to say and can desypher it better for me if needed.

What? I thought you did pretty good with that Doug..

You just went around the mountain instead of thru it...

Cheechblu, go after the interior of that fire box with a wire brush and scour off the ash build up. It's hurting your heat transfer efficiency..

Hello everyone. Long time lurker, first time poster. Hope I can help ur dilema.

My only addition to the posts mentioned pertain to your grates. They look nearly identical to the ones on my Mark I however I only have 2 grates and you have 4. The "teeth" as I will call them appear to be completely caked with ash. Before you light it back off try to find a way to clean them out. It looks like the only way for your ash to be shaken down is between each section of grate instead of between AND through them.

I would bet that between cleaning the grates and following the "air from underneath" principle it should improve. Good luck.

Bopper

I have a marathon Coal boiler. These units burn coal just fine do not block off any of the load door above fire air ports like someone here suggested that is stupid. The unit you have is a furnace. I believe you have the unit with the seconadary heat exchanger. There is a by pass to direct the heat somewhere look for it. I have burned anthracite and bitumionous coal in my boiler and it works fine. With the above fire air you have to establish a good coal fire with depth. I cheat and use the ash pan door to get the air ripping through the grates once you have the fire established and drafting. You back off the secondary air enough to supply just enough air to keep the voilitales light. All of your air will come from the ashpan door(primary air) under the grates. These units have been used for ever and they work well. Do not listen to people calling these units junk. If you are in doubt call the manufacturer. The mans name who owns the company is Tom ( I believe Tom Parker) I think the son is now running the company they may help you out.

for the rest of you just go to the website and look. and you will see the design. This man has a furnace not a boiler so go see the specs and design.

I would not burn oil in this unit because there are not as efficent as a dedicated oil furnace but u work with what you have. These units are designed for coal, the wood based fireboxes are round and have round cast iron tubular pipe grates. you will figure your issue out. Good Luck.

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I am not trying to be a jerk I am working and do not have alot of time to post I typed that from my blackberry. I just wanted to help him out. He needs that over fire air to adjust so the air ratio to avoid a puff back. Keep your ego in check dude. I am not starting a war sorry if I made you mad. Cyber36 used to have one of these units reach out to him he will share his in's and out's with you.