Grates VS. Firebricks?

[laynes69]

I have a new woodfurnace that is a basically a secondary combustion wood stove, surrounded by an air jacket. I noticed on it, and almost all of epa woodstoves, they dont use grates, or shaker grates just firebrick. My though was if wood is burned on grates that it would burn from the bottom and then from the top allowing it to burn faster. With firebricks, there is no air coming under the fire, but all from the airwash and the seconday burn tubes. This way the wood burns slower, and more even. Is this true? It makes sense in my mind, but I was wondering with my new purchase. I do know the shaker units would also burn coal, but i'm taking about wood units only.

 

[stejus]

I have a new woodfurnace that is a basically a secondary combustion wood stove, surrounded by an air jacket. I noticed on it, and almost all of epa woodstoves, they dont use grates, or shaker grates just firebrick. My though was if wood is burned on grates that it would burn from the bottom and then from the top allowing it to burn faster. With firebricks, there is no air coming under the fire, but all from the airwash and the seconday burn tubes. This way the wood burns slower, and more even. Is this true? It makes sense in my mind, but I was wondering with my new purchase. I do know the shaker units would also burn coal, but i'm taking about wood units only.

Wood will burn better on a bed of ash. Most manuals state to leave an inch or two of ash and not clean right down to the firebrick. Air moves through the ash and coals.

 

[humpin iron]

when you were a boy scout.........did you carry a grate to build campfires on?

 

[laynes69]

Dunno, never was. I was just thinking about the modern woodstoves to the older ones with grates. I figured the one with grates would burn quicker.

 

[laynes69]

Thats what I figured. But wasn't sure. I can't wait till fall to fire up the new beast! It will be a whole new ballpark for me, and my wife.

 

[summit]

if you use fireplace grates in something that is designed like that, you would likely melt the thing down. you'd have air coming in under the firemass in large quantities, like leaving the ashpan door open on a cast stove with a load of wood. we did that with a junk stove that got hauled outta someones house when we put a new one in. It had an 8" collar, we had a 6" metalbestos in a garage full of gas cans, pellets, and chopped up pallets for the fire .(ya know, garage stove fuel). put a 8 to 6 22gauge (not the wussy 24 gauge stuff, mind you!) adaptor on her, and ran the pipe to the metalbestos. within 15 minute with the fire going on the fireplace grate, the 8 to 6 adaptor had turned cherry red, and was sinking into itself as the steel got soft and our unsecured (forgot the screws in the pipe, but we did remember the beer!) stove pipe hooked to the slip connector in the ceiling started sliding down from extreme expansion. its a good thing we were just screwing around and were there to monitor the situation. despite out best efforts to shut the thing down, it pretty much raged hard untill the chopped up spruce and hemlock pallet wood ran down to coals. took about 20 minutes for the adaptor to stop glowing red. granted, the stove leaked air thru all kinds of gaps, but it was still a humbling experience, and also made me realize why in the manuals for these things they tell you not to elevate the fire on fireplace grates inside the stove.

 

[madrone]

:bug:
Yikes! Great story. That pretty much answers that question.

 

[drdoct]

I was wondering the same thing when I was looking at newer stoves. Then I was wondering how I was going to put the wood in. Burning in an epa stove is a whole new experience from everything you've ever known about burning. The epa stove has a ton of air and if your wood is semi dry it burns like crazy. If you stacked and packed wood in an old fireplace/stove like you do in an epa model, it wouldn't burn at all. Therefore you needed a grate and lots of air gaps. Maybe 2 logs going E/W and one or two across the top going somewhat N/S. All that space to try and get any air you can in there to get those top two logs to burn. The bottom 2 were just to create the air pockets and burned slowly. With your new stove/furnace you'll get your fire going and then put your wood in until it's stuffed and you can't fit anymore. Close the door and the air and it just goes to town. I love the epa designs and how it makes the air jet in. Never going back to the old way of firing again. Enjoy your new furnace.

 

[laynes69]

My furnace doesn't have anything to mess with but the thermostat. There are no air controls but a servo motor on the damper for the airwash or the primary air. The secondary air is fixed. Even then I have talked with owners of them and you load and set the thermostat and thats it. I won't be worried about it opening when heat is needed for its not a forced draft like the other just natural. It has a 3.5 cubic foot firebox, and its crazy thinking about this thing heating the house. The old basic furnace had a 6 or 7 cubic foot firebox and I was lucky to get an 8 hour burn when full to get a fairly clean burn. I've read some impressive things about fireboxes 3+ cubic feet on some of the epa stoves. One other thing, I have read to leave some room below the baffle for secondaries, is this true? Or can it be filled when its cold in the dead of winter.