Slowing down a coal fire with ashes ?

My bulk coal supplier, a sage coal burner for many years, recommended the old custom of throwing ashes on the top of the coal bed to slow the fire. It makes sense since the ash would lower the flow of air through the coal bed and I guess you'd have to be careful about how much to put on so as not to snuff out the fire. Any experience with this ? Can the ashes be put on a newly filled coal bed or do ya have to wait until the bed is fully burning ?

I think that it would work, but the idea and practice probably came about from burning coal in older design stoves and boilers that were not very airtight and were difficult to control [limit] the air to the fire. I think that with a modern coal burner, you can easily control the heat from the fire with the air control..

With a Barometric damper properly installed and adjusted, you will have a steady chimney draft and will be able to set the air to the fire and get a steady burn rate.

Some people put a layer of Pea size coal over a coal bed of Nut coal to slow down the burn rate, limiting the air through the coal bed..

Greg L

Uglysquirrel:

I concur with Greg 100%. The best way to control the temperature of a hand fired coal stove is air flow. You have a Harmon Mark II? The round damper that spins on the front of your stove allows very precise air flow control.

The other way to control temperature??? Crack a window...

Good comments, guys. I did'nt put my supplier's comments in the context of using a older type of non-airtight stove.

Man-o-Man, I'm getting excited about this, the 7" baro R-C vent is in, Heat-Fab pipe in, got the Model 25 Dwyer, stove in basement last night. In prep for going down stairs, took out all the bricks, doors, grates, etc. A bare Mark II is pretty simple inside.

A lot of people do that, I had a few customers that would get like 4 ton of nut or pea and ton of rice for the same reason.

why a 7" baro on a 6" stove pipe what is the flue size in you chimney

Uglysquirrel wrote:My bulk coal supplier, a sage coal burner for many years, recommended the old custom of throwing ashes on the top of the coal bed to slow the fire.

That is exactly what it is, an old custom. Sort of like throwing dirt on a coffin before they lower it. It does work, but I believe it is really detrimental to the fire, not beneficial. The reason is your placing the ash on top of your fresh coal that is not burning. It will reduce the amount of air that THAT coal gets to it when it does take fire.

No that I think about it, it reminds me of EGR (exhaust gas recirculation) on a car engine. You know, run some burnt stuff through something you are trying to burn stuff in? How well does that work for you? It takes more fuel and has a variety of other issues as well as we all know.

Coal berner, regarding your 7" RC on a 6" pipe, the RC fields website recommends a 6" diameter but at the end of the file they note that if the chimney is over 16' ft, do a 7" (got one for $10 on ebay new !!!)'. My chimney is masonry, ~ 26-28 feet from top to basement flue. My feeble mind also remembers last year that when we had some high winds (on a hill with NW sky exposure) my oil burner (5" flue, 6" fields) was lightly slamming all the way open along with my wood stove pipe that was getting nice and hot due to all that wood heat getting sucked out. The wood stove did not have a fields control though it did have a damper and even then, with damper closed, I pretty much had to tighten down on the draft more. It's almost like a runaway pipe temp event. During these type wood events I imagined this heat is what coal can give off. Now I know that this coal heat can be controlled better.

I will say thought that putting the 7" galvinized shroud onto the 6" pipe was not too enjoyable . The heat fab pipe's thickness is not easy to cut, I cut the hole for the RC Fields 180 degrees from the pipe weld (I remembered !) . There are a couple of ~ .015- .020" spaces between the shroud and pipe and I think that is pretty normal and was thinking of sealing those spaces from the inside with hight temp rtv or the ceramic stove sealant from I believe Rutland. Any comments ?