Everything Drolet Tundra - Heatmax...

[laynes69]

Brenn, how does your house do in these temps now (mid 30's). We can go a half hour or more before dropping a degree in the home. Before I started concentrating on the house, as soon as the blower would shut off, the house would drop. At 28 degrees we couldn't heat the house past 68 running full tilt. Now a bed of coals at those temps will keep the house 73-75.

 

[brenndatomu]

Oh, it's not bad at all. If it was 35 out with no wind (it is a brick house, so wind is not quite as big of deal as with other types of construction), and the house was 72 inside, I would expect at least 8 hrs to get down to 70 (with no heat going)
As I have said before, the tiny little stove (1.2 CF) in the fireplace will raise the ground floor 3-5*, but with such a small firebox burn times are shorter, and full time heating with it would be a PITA, especially if you want to close a bedroom door or something. But it still goes to show that it is not that hard of a house to heat. If I had a bigger stove I would use it further into the depth of winter. A larger stove won't really (correctly) fit in the fireplace and there is no room for it outside the fireplace. Also, I hate cold floors, and the floors get cold when no heat is on in the basement so there is that...anyways...

Now a bed of coals at those temps will keep the house 73-75.

Coals just don't translate into heat upstairs....

 

[brenndatomu]

As I have said before, the tiny little stove (1.2 CF) in the fireplace will raise the ground floor 3-5*

On a day like today (mid 30s) I don't know if the Tundra is even capable of bringing the house temp up 3-5* with a stuffed to the gills load...maybe 3, not 5, no way

 

[laynes69]

On a day like today (mid 30s) I don't know if the Tundra is even capable of bringing the house temp up 3-5* with a stuffed to the gills load...maybe 3, not 5, no way

That's crazy....I see where your coming from. If your flue temps are low and your firebox is hot, the heat is going somewhere. If you have a plenum, that would be my choice.

 

[brenndatomu]

If you have a plenum, that would be my choice.

That's where this is headed I believe. I just wanted to take things one step at a time so to document what worked and what didn't. So far most of the stuff that I have tried during the last couple pages of discussion has helped, to some degree anyways

 

[STIHLY DAN]

OK let me give you the specs of what I have going on.
2800sqft total living space,
Tundra ducted to about 2000 sq ft, remaining 800 sqft is still being heated but no ducts to those rooms, really aren't any cold spots in the house with the doors left open to those rooms,
2x4 walls with 1" air seal done with closed cell spray foam, r13 batts over spray foam, yes insulation is compressed some, blown in attic insulation about 18-20 inches worth,
Ceiling heights are 10' minimum, 650 sq ft at 14' high, 150 sq ft at 12' , large windows and doors so alot of glass area as well. I am sure most of my heat is at the ceiling. When I get on the ladder and change a bulb you can really tell where the heat is. Right now its 30* outside 70* in the house and I just came down stairs, blower just turned off so you know I am down to just a few coals.
I wouldn't say my house is super insulated but Tundra is doing to job, I don't see how at 2500 sqft with 8'/9' ceilings and OK insulation the tundra wouldn't do it. To give you another example the past two years I used 1500gallons of oil each year. During the cold months it was exaclty 300 gallons on month. So you know now why I am trying wood.

With what you say you have for insulation, your oil usage is/was ridicules. You have something going on there.

 

[Builderml]

With what you say you have for insulation, your oil usage is/was ridicules. You have something going on there.

Your correct it is ridiculous, the problem is my own fault really. When I built the house I made the bright choice of putting the air handler in the attic. I wanted no Ductwork in the basement. Planned on finishing it. I also ran all metal round Ductwork wrapped with fiberglass I think r6 or r8. So now not only am I trying to heat the house but I also have to heat that Ductwork before any heat even gets into the house. On a 10 degree day you can only imagine how much heat I am wasting just figthing the unconditioned space. At the end of last year I said something has to change which is why I am doing wood now. I had a few options, burn wood, install another air handler in the basement along with all new ductwork, or remove existing insulation from ductwork and have the Ductwork all sprayfoamed. So I selected the wood route for now. If I had to guess I think 30-40% of the oil usuage was just the fact that the Ductwork is in unconditioned space.

 

[Builderml]

Brenn I think your going to find this interesting, so last night at about 8pm I load the firebox full of nice maple rounds everything from 1"-6" round, I went back upstairs thinking that should last the night with plenty of coals left in the morning, WRONG. At 12am I wake up and say heck its cold the tundra was cycling on and off already. I came downstairs and see a nice huge pile of coals but crap for heat coming off. I have never had this many coals before. I would say 3"-4" deep on the bottom. Keep in mind I haven't burnt a load of hardwood to date. The temp dropped down to 68* and its mid 20's outside. I said what the ****. I Also said hardwood my ass. So I loaded it back up with pine on top of the coal bed, its now 7 am so 7 hours later I am at the same point after I was with a full load of hardwood 4 hours later. It's almost like the coals don't want to burn or give heat. Again. I have never had this many coals with the softwood. While a nice bed of coals is great but these aren't coal burning stoves no air is coming in from the bottom which makes a 4" bed of coals useless. It has me thinking that I am able to get more heat out of the tundra with softwood, while hardwood may be able to give long lasting coal beds if I can't burn the coals to extract the heat what good are they. After all we need to get the flames/ heat into the heat exchanger not in the firebox. This should be interesting to play around with. Brenn have you tried burning a full load of nice seasoned softwood? Very little coals at the end of the burn. Telling me I am burning everything and getting the btu's from it. I am sure many will not agree but I can only tell you what I am seeing. Hope this helps some Brenn.

 

[Builderml]

Also just another little note on a 4" bed of coals only the top 1" is red and rest are black rendering those cold and useless, also the 4" bed doesn't allow me to put in as much wood in the next fill up.

 

[maple1]

I went through that exact thing with my old boiler. Had to shovel out hot coals most mornings to get more fuel in - liquid cooled firebox that the fire was resting on didn't help that, and no grates or under fire or through bed air. There is definitely no one size fits all in this wood burning thing - way too many variables in appliances, heat loads, fuel types, on & on. Now with my new boiler, I have a downdraft through the coal bed and that's the end of those problems - total different animals. Coal beds might heat for some people & appliances & situations, but certainly not all.

 

[Builderml]

I went through that exact thing with my old boiler. Had to shovel out hot coals most mornings to get more fuel in - liquid cooled firebox that the fire was resting on didn't help that, and no grates or under fire or through bed air. There is definitely no one size fits all in this wood burning thing - way too many variables in appliances, heat loads, fuel types, on & on. Now with my new boiler, I have a downdraft through the coal bed and that's the end of those problems - total different animals. Coal beds might heat for some people & appliances & situations, but certainly not all.

Very well said. No air to fuel = no heat from fuel

 

[KARB2014]

Very well said. No air to fuel = no heat from fuel

Well what I did last year during the polar vortex I made a grate out of 3/8 304. I will say it helped eliminate the coal bed problem. I removed it at end of last year and haven't used it yet. If you have a large heat load you will develop a large coal bed with hardwood. I tried the grate and it helped a lot. The reason I haven't put it back in yet is because I wanted to see if it was my wood. So far I would have to say that it is not my wood it just the nature of the epa box's.

 

[brenndatomu]

Brenn have you tried burning a full load of nice seasoned softwood?

I think you may be on to something here @Builderml .
No I haven't tried all softwood. A piece or two here and there, but that is it...very interesting indeed. I have been burning some Ash and Cherry, a lil Elm too. All the rest of my stuff is even more BTU packed so...
I do remember reading of these guys (Tundra owners) have problems with coal buildup during the really cold parts of the winter last year. It is a EPA firebox issue, the stove guys have it too when they push 'em hard.
One feature of my temperature controller is the ability to have it open the damper when the flue temp drops too far, @3fordasho has been using his to reduce coal buildup. I haven't used that feature yet because I thought it would reduce "burn time". I haven't had a coal buildup problem yet, but, it has been warmer out and I haven't been loading fresh wood onto a big pile of coals...heat output is defiantly much better with flames rolling in the firebox. I can really only raise the temp in the house when I have flames...looks like I have more things to try now.
1. Use the low temp feature in the temp controller.
2. I had thought of removing the insulation blanket behind the firebrick in an attempt to get some of the heat from the coals to pass through the firebox walls to the air.
3. Insulate the cabinet. There is a ton of heat lost to the furnace room as I said before.
4. Install supply plenum.
5. Maybe try to fab up a grate like @KARB2014 did? The more I think about this...yeah, the ideas are rollin now!

If I recall correctly, this was the exact problem spidey had with his "stovace" in that thread(s) that I had mentioned earlier, this was over on AS a couple years back....coal buildup and no heat output!
Maybe this is why my Yukon was working so well for me as far as heat ouput (other than being cantankerous to get "dialed in" on each and every load) because I have both air under the fire and now a proper secondary burn system. (I modded the secondary air system)(the factory secondary burn system is better than nothing, but just barely)

 

[brenndatomu]

Hey @laynes69 , you say you can cruise along no problem on a load of coals, huh? I wonder if the Caddy has the same insulation blanket behind the firebrick that the Tundra has. I can't seem to find a parts diagram online for a Caddy.

It is gonna be warm here the rest of this week (I just saw the forecast for Christmas day...almost 70!!) so I will be letting the Tundra go cold and fire the lil stove upstairs...give me a chance to tinker on Tundra...

 

[brenndatomu]

I made a grate out of 3/8 304.

Woooweee! I bet that weren't cheap! Tell us more about this...got pics? Did it affect having coals enough to bring to the front for the next fire? How big are your slots...or holes? I guess you had to lift it up to dig ashes out? How often?

 

[laynes69]

Yeah, we have the insulation blanket under the floor and walls of the furnace. Average register temps in the dead of winter average 90-100 degrees, more than enough to keep the house warm. I'm sure the difference also is the 11.5" limit/control in the plenum for air temps, and the lack of a false roof. If you go the plenum route, I would try a limit/control and mount it like a Caddy. I will say however, the tighter the home, the less the problem is with a coalbed.

 

[KARB2014]

Woooweee! I bet that weren't cheap! Tell us more about this...got pics? Did it affect having coals enough to bring to the front for the next fire? How big are your slots...or holes? I guess you had to lift it up to dig ashes out? How often?

I will give all the specs tomorrow when I get to work, I have everthing in a model. It was free I have a bunch of 3/8 sheet that was never used from a job I just lasered it off the clock. The biggest reason I hope I don't have to go back to it is because it was a pain to have to Lift it to empty the ash. I had a pretty good system down. I would use the poker Drolet supplied to wedge it up and scoop the ash out. It eliminated the coaling issues. I got the idea after reading about W.S. issues. The 2nd problem was if you let it go to long it was a royal pain to relight. The remaining small coals would fall through. But it did give me more usable heat through out the burn cycle. With the grate you could see small blue flames coming up through a bright red coal bed with the damper closed. To be honest I can really see me having to put it back in once the temps decide to drop and stay there. This weekend was the first cold spell we had and I already had a massive amount of coals. Without the grate I have to leave the door cracked and damper open to reduce the pile. I was tempted to cut a 5 or 6 in slot the bottom from front to back. Then I was going to fab the ash tray to accept fire rop to make sure it would seal. I decided to give it one more chance. Also going back and reading the other stuff I posted I must emphasize I did have issues last winter. Coaling being the biggest.

 

[brenndatomu]

I loud the firebox full as i can get it and let the load get nice and hot, usually i'll let it bounce off the high limit a couple times

I load firebox full and just let her go wide open, She bounces off the high limit most of the time for the first hour.

So how loud does it get?
Good thing you have the firebrick in the front, bouncing off the high limit switch regularly sounds like a recipe for crack(s) if you know what I'm saying

 

[DoubleB]

bouncing off the high limit switch regularly sounds like a recipe for crack(s)

I agree. Mine is cracked. And it's never even hit the factory high-limit that I'm aware of. I'm still modifying it to stay as far away from high temps as I can while still getting good secondaries and a clean burn.

 

[brenndatomu]

I'm still modifying it to stay as far away from high temps as I can while still getting good secondaries and a clean burn.

Something new in the works at the DoubleB ranch?

 

[DoubleB]

Something new in the works at the DoubleB ranch?

Haaa, yea well at first I thought I could just replace the high-limit with a lower temp snap disc, but that didn't work as well as I hoped. Snap disc was either too low and the fire would smolder a few cycles before secondaries took off well, or else was too high for what I wanted. Wasn't much middle ground, and the plenum just doesn't react very quickly to overfiring or smoldering.

Now my plan is to add a snap disc on the flue. Using the IR thermometer it looks like the flue reacts quickly to fire conditions and I can also get a snap disc in the range where, if I leave the damper wide open, it will cut out the damper if it gets hotter than I want, but keep things hot enough that I don't smolder if the wood isn't charred enough for damper fully closed.

My goal is to make it fool-proof so even if the manual switch, tstat, or bathroom timer opens the damper too long, that the temp control keeps it above secondaries only and below over-firing. I still find that amount of remaining coals, size and species of wood, quantity of wood, remaining furnace temp, etc. are too many variables to know how long to set the bathroom timer for when I reload. I want to set it for a long time (30+ minutes) and walk away without worrying about overheating things.

Now I just need to get the snap disc for the flue, and find time to do it. I intend to write things up here once I get something I'm happy with.

 

[Builderml]

I think I found the solution for now. Last night I lined the bottom with pine. Put the maple on top much much less coals this morning. It's 10 hours later and the temp is at 68. I made only 4 hours the night before. Granted it was much colder out too. I'll try this for awhile before I fab up some grates. I have plenty of pine. It took almost 20 hours to burn down the coals after which point I said enough of this and shoveled the rest out.

 

[Builderml]

I am going to try loading the pine on the bottom east/ west with maple north/south on top to see how that does. Only problem is most of my stuff is cut to long for that. I hope it will act as a btu producing grate. I hate to reduce the firebox size with grates.

 

[KARB2014]

Here is a drawing of the grate. It just doesn't show the legs I welded onto it. I made them 3/4 tall. I was trying not to lose much firebox volume, I did not remove the fire brick on the bottom. I may design another one and put a little more thought into the spacing and slot shape and size. This one was just an experiment. I will say I was surprised by how much the current one bowed. I would have to say it bowed up in the middle by about an 1".

 

[sloeffle]

On a day like today (mid 30s) I don't know if the Tundra is even capable of bringing the house temp up 3-5* with a stuffed to the gills load...maybe 3, not 5, no way

I was having the same problems with my Caddy when temp were below 15 or 20F. Turned the fan speed up and that seems to have helped. Have you thought about turning your fan speed up ?