Stacking envi-blocks

[hyperion]

This past weekend we experimented with envi-blocks for the first time, and we are generally impressed. They burn clean and hot, and kept us warm through the big snow storm in the north east. The only problem is it seemed like we were going through a lot of them. It took 8 bricks for a 12-hour burn. I am guessing it might be that we didn't pack them closely. We were told repeatedly that these burn hot and not to fill up and since it's the first time, we were really cautious and only burned 2-3 bricks at a time. They actually looked lost in our large wood stove. We have an original Vermont Casting Defiant I from 1979 and it's massive (35"x24"x14"). I'd say we can easily pack 20 bricks in with plenty of room to spare, but that seems suicidal.

So the question is, what's the most of these you have burned (safely) at a time, and how did you stack them?

 

[nlittle]

I burn the woodbricks which are like biobricks. So, far I have put a max of about 14 in. I am not sure of the shape of yours but if you stack them in alternating directions the air does not get through as well and they burn slower. I also make sure the floor is nice and flat, no big leftovers to topple a pile etc. last thing I do is use the back of the stove, instead of the middle. That keeps the flames from surrounding the pile completely. Good luck!

 

[Eric Gradoia]

Hyper -

I burned these last year for the first time and was really quite impressed with them. I have a Morso 3610; the firebox is 29 W X 24 D X 31 H. I would get a bed of coals going and load two layers of blocks into the stove. I would put four blocks on the bottom running N/S spaced a couple of inches apart ( I I I I) then a second layer of four running E/W also spaced apart (= =). The spacing is important, not only does it let the air circulate; I found that these guys like to swell up as they burn.

Eight blocks would give me a solid 8 hour burn with enough coals to reload to. These things pack a lot of energy in them. I could probably get another two in the stove if I wanted to, but heat wise, I have no need to. Keep an eye on these things when you put a load in. You can easily overfire if you don't watch out.

These heated the better part of our house for three days during the ice storm of 2008; I was sold after that. They turned out to be one of those few products to actually live up to their claims.

Good luck with them.

 

[WoodNewbie]

Thansk for sharing the info. Are you talking about the regular EnviBlocks (the big ones) or the smaller version of them (Envi-8)?

 

[Eric Gradoia]

I was burning the regular enviblocks.

 

[hyperion]

Thansk for sharing the info. Are you talking about the regular EnviBlocks (the big ones) or the smaller version of them (Envi-8)?

We burned the larger envi-blocks (4"x4"x10.5").

 

[spirilis]

This past weekend we experimented with envi-blocks for the first time, and we are generally impressed. They burn clean and hot, and kept us warm through the big snow storm in the north east. The only problem is it seemed like we were going through a lot of them. It took 8 bricks for a 12-hour burn. I am guessing it might be that we didn't pack them closely. We were told repeatedly that these burn hot and not to fill up and since it's the first time, we were really cautious and only burned 2-3 bricks at a time. They actually looked lost in our large wood stove. We have an original Vermont Casting Defiant I from 1979 and it's massive (35"x24"x14"). I'd say we can easily pack 20 bricks in with plenty of room to spare, but that seems suicidal.

So the question is, what's the most of these you have burned (safely) at a time, and how did you stack them?

I have the VC Defiant II from 1980 and I burn wood bricks (small 2lb bricks like biobricks). I don't have, shall we call it, stellar draft so I don't mess with stacking the bricks much, preferring short & hot fires that raise the house by 12-13F lol.

My preferred stacking configuration involves an elongated teepee of 6 bricks (takes up a good amount of the Defiant's firebox, and I prefer to get the left-end brick around 3-4 inches away from the primary air manifold on the left side) with 1 or 2 slats of pallet wood on top. I guess you could put wood bricks on top of that. The elongated teepee makes a nice hot core to ignite the bricks and keep them burning hot, and they burn well during the coaling stage stacked like that. In my small house (about 800sqft in the upstairs level) this configuration will raise the HVAC thermostat temp by ~12-14F within a couple hours when I have a fan pointing at the living room. At night it generally provides ~6-7 total hours of heat before the thermostat's back down to where it started. This is burning the Defiant in updraft mode the whole time, so a good amount of heat is lost through the chimney but once the Defiant starts dialling back its primary air flap more heat gets retained. My downdraft mode doesn't seem to work right so I don't use it.

I haven't tried extending my burn times with additional bricks (could try laying bricks on the floor and build the teepee on top of that I guess) but I'm not sure I'd want to. With the Defiant the additional bricks will likely start to smolder, especially once the thermostat flap on the back starts to close down--all oxygen used to smolder the wood and no oxygen left to ignite the smoke. Using an IR gun thermometer I find the Defiant likes to cruise around 550-600F (griddle-top) with the fluepipe right after the exit ~400-500F until the coaling stage, and usually the bricks are entering the coaling stage ~15-30min after the thermostat flap starts to close down.

Another idea might be to stack a tight mass of bricks on one side of the stove, then a small teepee on the other side (probably the left side, near the primary air manifold)--the teepee will start the stove and eventually the tight brick mass will catch and extend the burn times. Might be worth an experiment soon. Everyone says these bricks burn longer when stacked in a mass.

I have found that the exact # of bricks burning at one time is crucial. 2 or 3 bricks won't burn very hot and I'd wonder how cleanly they're burning. 4 barely cuts it, 5 goes well enough, 6 definitely does the trick. I tried two teepees of 4 and 5 next to one another and had the stove overfiring in a hurry. Keep in mind my draft situation isn't all that good--flue length is only ~10ft and my flue liner is way oversized (12x12 clay), so a Defiant with a better chimney setup might draft hard enough to get fewer bricks burning hot.

 

[spirilis]

Lol sorry just realized you're using those Envi-blocks which are larger. These compressed sawdust products do burn fast, might work a bit better if you have some way to trap the heat in the Defiant (flue damper perhaps?) I used to have a flue damper on mine but took it out b/c my draft sucked (or didn't, actually... heh) with it in there even when it's wide open.

Once thing is certain, the Defiant's baffle isn't terribly long and lets a lot of heat out the chimney unless you can use the downdraft secondary burn system which elongates the flue path.

 

[hyperion]

Spirilis, what do you mean by an elongated teepee? I can see a teepee with 4 bricks, but don't see how to elongate with 2 more bricks?

 

[spirilis]

Spirilis, what do you mean by an elongated teepee? I can see a teepee with 4 bricks, but don't see how to elongate with 2 more bricks?

Umm, hopefully this picture depicts it correctly-

Two pairs of bricks leaning against one another, arranged side by side, with a single brick at each end leaning in. Gotta dig the bricks into the ash well to make them stay put and not collapse. Then I add 1 or 2 slats of pallet wood on top and light the firestarter underneath the teepee (typically a piece of fatwood and/or tiny starterlogg pieces, with some firestarter gel drizzled between the pieces before I lay the teepee down--that way I just have to torch one little spot of the gel and it'll fill the underside of the teepee with fire!)

 

[hyperion]

spirilis, got it, thanks for the wonderful illustration! I might give that a try. Although with the larger-sized envi blocks, I am thinking maybe starting with a 4-teepee and once they get going well, pull them down and lay another 4 on top, like what Count Rumford was doing, and see how long a burn that will hold for us.