Damper Vs Draft

damper vs draft

PostBy: mythreesons On: Wed Oct 25, 2006 2:48 pm

I have a new wood/coal furnace and the bottom ash pan door has a spin type damper on it. I'm reading a lot about coal and that it should burn from the bottom up and the need for a bottom draft. Is this differant form the damper on my ash pan door? Any advise would be appreciated.

PostBy: laynes69 On: Wed Oct 25, 2006 7:48 pm

The ash pan door damper should be open for coal. You want air under the fire. The feed door damper (OR Thermostat) should be closed if burning coal. Otherwise you can lose draft from below and lose your fire. With wood you want to use the feed door damper, to help bring in air to burn secondary gases (Smoke). Hope this helps.

PostBy: mythreesons On: Tue Nov 21, 2006 12:34 am

It's gotten colder here the past few nights in the mid 20's. I'm noticing my furnace is not keeping the house as warm as it has been. The coal is red hot and I'm loading it up real good. Could the heat be going up the chimney due to not having barometric damper? Thanks.

Re: damper vs draft

PostBy: Gary in Pennsylvania On: Tue Nov 21, 2006 8:17 am

mythreesons wrote:I have a new wood/coal furnace and the bottom ash pan door has a spin type damper on it.

That's all I have on my ash door also. I have the main 'Coal Door' with the view-thru glass, and an ash pan door with a single open-close twist damper knob.

When I throw a new load of coal in....It's a big black mound and I see no red/fire nuthin'. I leave the ash door wide open AS I SIT THERE flippin through the TV. I'll leave the ash door open for maybe 3-4 minutes and then shut 'er up. I set my ash pan draft knob to fully closed and back it out JUST A MERE QUARTER turn for the warm days we were having last week and about 3/4 turn yestrday when it was chilly up here in the Pocono Mountains.
In the dead of winter.....I gotta back it out one turn, but no more. She gets too hot.
Gary in Pennsylvania

PostBy: barley master On: Tue Nov 21, 2006 8:49 am

your ash door "spinner" is the bottom draft. im not fond of multi fuel stoves. which I havent seen too many wood burners with baros. and the contol of the air, heat, and fire are controlled by one adjustment.

i have seen stoves where you operate this for wood and this and that for coal and its a happy medium between the fuels and thats why I don't like them. but each to thier own.

i would say put one on the unit. then check your draft and then hone you operating skills. remember it takes time for "it " to react. gary sips coffee and watches the tube while waiting for the stove to rebound, since burning nut in a stove made for pea I have to wait a real long time for a reaction then im good for 12>hrs 8) in the mean time I go start a fire in my wood stove or do something during that time, come back dampen it off and plenty of heat.

what size coal are you using. what do your ashes look like.
barley master

PostBy: mythreesons On: Tue Nov 21, 2006 1:54 pm

I'm burning nut coal, pea would fall through my grates. The ashes are a whitish gray with very little solids in it. The coal had been working great, I was ready to sell a few cords of wood because I was so happy with the operation. The last two nights have been around 25 and the coal seemed to stop getting hot enough. Last night I left the ash pan door open for 20 minutes and it got red hot, but the blower limit switch only went to 130. My set points are 150 to kick on and 100 to shut off. I then added two logs and opened my feed door damper from closed to low and within 5 minutes the blowers kicked on. This was my thought behind needing a barometric damper but not having any type of air induction besides the ash pan damper I thought this might be part of the problem as well. I guess I want to know if all the heat is going up the chimney due to the colder temperatures and will a baro help or is it the air induction thing? Thanks.

PostBy: Gary in Pennsylvania On: Tue Nov 21, 2006 2:15 pm

barley master wrote: Gary sips coffee and watches the tube while waiting for the stove to rebound, since burning nut in a stove made for pea I have to wait a real long time for a reaction then I’m good for 12>hrs

Sorta. If found out the hard way (2 years ago) that if I chuck a full bucket of coal on the coal bed (even if it's hummin' pretty good), and immediately close the ash door, I could (and have) loose the fire.

NOW, I throw in a bucketful and leave the ash door open long enough to guarantee that the new mound has been brought up to temps and the bottom nuts have caught. I know I'm ready when I see a faint glimmer of bright white/yelllow light peeking up through the mound here and there. Then I close the ash door being careful to utilize my new ANTI-BACKFIRE technique. 8) :wink:
Once the ash door is closed, I cannot see any fire. There is no blue dance. But I KNOW she's cooking'! And I too easily get 12+hours outta that setup. Maybe less when we get to the teens and single digits.
Gary in Pennsylvania

PostBy: mythreesons On: Tue Nov 21, 2006 5:31 pm

Do you have a fan or cumbustion air feeding from below the grates, or just the spinner damper? Do you think because of the cold weather the heat is being drawn up the chimney? If so what can I do? Thanks.

PostBy: Gary in Pennsylvania On: Tue Nov 21, 2006 5:43 pm

I do not have a fan feeding combustion. I have an air jacket that is built into my stove (it's a Harman Insert) that blows air around the stove in a steel sleeve and into the living area. It’s toasty hot.
See it here:
Here's my Harman insert (pics)...

The air in the jacket does not interact with the coal.

The only thermometer I use is a magnetic jobbie stuck to the outside of the box. I keep it between 275-350 degrees.

When the fire is really hummin' and go outside, I cannot observe ANYTHING coming from the chimney. I even hold very still and try to notce heat wave disturbance like you see coming off of a hot asphalt road in the height of July. Nuthin. My CO2 reader never makes a sound.

I hardly have to do too much with the fire....so it's not skill. Maybe I just lucked out cuz this is the easiest, cheapest heat I've ever had!
Gary in Pennsylvania

PostBy: coalwarmth On: Mon Nov 27, 2006 10:04 pm

To Gary in Pennsylvania.
I have some questions for you on the instalation of your Harman insert. When you can get back to me please.

PostBy: greg white On: Tue Nov 28, 2006 8:42 am

I have a Harman "dual fuel"SF150,I could not be happier with its performance,it has draft knobs on the loading door and 1 on the ash pan door.Each knob has 5 fins,on a 30 degree nite I can run bottom knob 3/5s of 1 turn open,top knob 1/2 turn open,this is burning coal.
After 30 plus years of burning wood,this long lasting burn is the bees knees.
I was told that I need "some" air coming in the top of coal to keep the gases created or released lit,hence cracking the top knob a bit.
my .02 cents(O.K..03 cents) :)
greg white

PostBy: laynes69 On: Tue Nov 28, 2006 5:14 pm

I have a wood/coal furnace. What I would check is make sure the inner firebox walls are cleaned, that way the heat will transfer quicker. I have the same issues because I don't know how far the draft has to be open. I think I had mine set to 2 1/2 turns open, which equals maybe an 1/8 of an inch. I installed a new barometric damper because my old one was junk. So far I have used less wood, and the furnace stays hotter. I'll need to try coal again. Our chimney is a 35 foot masonary chimney which drafts ice cold, So I have noticed a difference with a Baro installed. What type of furnace do you have? And how tall is your chimney? If you install a baro just remember if you have a chimney fire, that thing will open and feed the fire in the chimney, So just keep an eye on things. Sounds like you may need more draft to feed the air to the coals. Also check and make sure your grates aren't clogged.

PostBy: Gary in Pennsylvania On: Wed Nov 29, 2006 8:44 am

coalwarmth wrote:To Gary in Pennsylvania.
I have some questions for you on the instalation of your Harman insert. When you can get back to me please.

Sorry for missing this yesterday coalwarmth....

We bought the house in Aug 2003 and it was already installed. I have a bunch of pics of the stove and that's it. I have to draft measuring meters, exhaust temp thermometers, etc...
Even when it's near 70degrees outside.....My fire doesn't doesn't go out (external brick chimney with metal liner running up inside) - but it's AWFULLY HOT downstairs. My wife keeps the two young boys shirtless and in shorts upstairs in our split-level home during this ugly warm stretch that NE Pennsylvania is dealing with.

I keep the little magnetic thermometer stuck to the outside of the box at about 250-300 degrees on the warm days ( with ALL windows in the house open! ). When it finally gets cold.....I keep it between 300 and 350 degrees. When single digit cold comes, 375-400. All that is controlled by my spinner draft knob. Right now, she's burning with barely a 6th or a 5th of a turn open from completely closed. It's barely breathing......But she never goes out!

I LOVE this coal!!!!!!!!!!

I'll try to answer whatever questions you have though.!
Gary in Pennsylvania

PostBy: italia899 On: Fri Dec 15, 2006 12:26 pm

I have something to add and a question regarding damper and draft. I have a brunco insert. It has a bimetal draft setting on the right side for underneath the grates. It has the spinner knobs for draft when burning wood or bituminous. Lastly it has a manual hand damper just above the baffle plate that you can open and close almost all the way.

I have found that the following adjustments work best in all weather for burning anthracite:
-bimetal damper open all the way
-spinner knobs closed all the way
-manual hand damper closed all the way (there still is a
gap though)

With this set-up my stove will burn 11-16 hrs. based on the weather conditions and the temp. on the top of the stove is 450-475 degrees F. When the hand damper is open farther the temp. of the stove is less, but I get the same burn times when the damper is closed all the way but a hotter stove.

My question is am I getting a better draft with the manual damper closed? It seems that my stove is more efficient (same burn times, hotter stove). In the past, when I had the damper open more on warmer days my fire would not burn as hot or the coal efficiency would not be as good, i.e., more solid ash than fine, powdery ash, more unburnt coal dropping in ash pan after shake, etc. Does anyone else have a manual top damper and had similar success?

Stove/Furnace Make: Brunco
Stove/Furnace Model: Hearthglow


PostBy: hgmd1 On: Fri Dec 15, 2006 7:08 pm

If you opened the upper manual damper then all of your heat would go up the chimney as was happening all last year in my Hitzer 503. I now have a damper that I made for the stove. You know if you have enough draft if there is no smoke in your house and your carbon monoxide detector is fine.Too much draft and you will be heating the great outdoors.