Everything Drolet Tundra - Heatmax...

[brenndatomu]

Do you guys ever just consider these furnaces to be a big Magic Heat device?

Huh?
Yeah, I guess, kinda...throw wood in 'em, light it...heat! Dunno about magic...but a good heat(ing) device, yeah...better than heating with snowballs

 

[brenndatomu]

@brenndatomu are you still running with about 50% of your secondary air cut off?

Yup.
Here's some pics of my hillbilly turb...

Had 72* in the house after work today, 10+ hours since the AM load. The low last night was 12* and high today was mid 30s...I just now reloaded at 6:30 and the house was still 71*...that's 12+ hours on that load...

 

[STIHLY DAN]

Sounds like you have it down pat. Also I think some of your issues may have been comparing it to the Yukon. Low and slow rather than hot and fast.

 

[brenndatomu]

Sounds like you have it down pat. Also I think some of your issues may have been comparing it to the Yukon. Low and slow rather than hot and fast.

Low and slow is right! I'm sure that comparison was not helping my expectations any.
One thing that may play a part here is the size of the loads, the Tundra really starts to walk n talk when you load 'er up. With all the warm weather we had I was doing smaller loads. On the Yukon, the load size does impact heat output, but not to the extent of the Tundra.
I'm not done foolin with this thing yet, but if I could get it to raise the house temp more than 1, maybe two degrees during the peak of the burn, I guess I'd call this whole experiment a success. I really like how easy it is to run compared to my modded Yukon, especially with the temp controller

 

[Highbeam]

Huh?
Yeah, I guess, kinda...throw wood in 'em, light it...heat! Dunno about magic...but a good heat(ing) device, yeah...better than heating with snowballs

There is a device called a "magic heat" that mounts in the flue of regular wood stoves. It has tubes and a blower to extract flue gas heat much like these furnaces. The woodstove folks hate them, call them bad names, and ridicule those who use them.

 

[brenndatomu]

There is a device called a "magic heat" that mounts in the flue of regular wood stoves. It has tubes and a blower to extract flue gas heat much like these furnaces. The woodstove folks hate them, call them bad names, and ridicule those who use them.

Ahh, now I gotcha. I had one of those things...creosote factory! But to be fair, I was pretty early on in my wood burning learning curve and I was burning pretty wet wood. I think they would actually work pretty good used with a smoke dragon that is on a dry wood diet...

 

[DoubleB]

Well, when I got home from work tstat said 71*, this was at 4:30, so almost 10.5 hrs, high of 25* out today. Not too bad I guess, still had good coals for an easy relight. Threw in some more Hickory and Oak...it took a while, but it is back up to 72* in here as of about 8:30-9:00. I really don't like that I can only raise the house temp 1, maybe 2* during the hottest part of the burn, seems like it should do more...

Brenn,
As a datapoint, you're starting to get about the same results that I am by now. In this weather I raise the temp about 4F during a load, but that's just dumping it all on the 1000 sqft 1st floor and it takes a while for the heat to flow upstairs. My loads last a couple hours shorter than yours did, but I'm mostly box elder (hey, it works for me).

Also, I like your turb. I don't have much experience with them, but you got me to thinking that it might be just as easy to slide a 6" wide strip of appropriate sheet metal and take some time to twist it into a helix. I gather that's the idea.

 

[brenndatomu]

I like your turb. I don't have much experience with them, but you got me to thinking that it might be just as easy to slide a 6" wide strip of appropriate sheet metal and take some time to twist it into a helix. I gather that's the idea.

Yeah you got the basic idea.
Basically you want the flue gasses to have as much interaction with the HE walls as possible. If you look at the way air likes to flow through a tube, high velocity gasses will tend to kinda punch a hole in the center, leaving the furnace without really having much direct contact with the HE walls. And it is important to "turbulate" the air without blocking overall flow capacity of the tube much.
Doing a 6" wide helix would be tough to DIY IMO, unless you have some pretty good metal working skills/tools. I got the idea for the one I made from that website I linked to earlier today.
Read up on the threads here from a few weeks ago, the boiler guys were doing all kinds of turb comparisons...got my wheels a turnin...

 

[Builderml]

Brenn congrats on your success, now with the lower temps 4* this morning and 7* or so yesterday the tundra only held house temps. 67-68.No way was I able to raise them at that low a temp out. Getting about 3-4 hours on a load of softwood and a few maple pieces. Finally was able to start raising temps at about the 15*-20* mark outside. Only about 1 or 2 degrees. Looks like you have the keys to the F350 now. I may have to get some info from you about the temp controller in the future but for now I am good with what I can do.

 

[laynes69]

Brenn, break out the new camera when you get it, and you'll see better results when things improve. Even then, it sounds like things are doing well. Stuffing the firebox completely full, you'd be around 3.5 cuft ft. With splits not as long, and not completely full, your probably in the upper 2 to 3 cut ft. range. To keep a house warm for that long on that amount of wood is not bad, considering old school furnaces could use double or more.

 

[brenndatomu]

Brenn, break out the new camera when you get it, and you'll see better results.

Just got it today...played for an hour or so. Didn't see anything that I didn't suspect already. Not real cold out though.

To keep a house warm for that long on that amount of wood is not bad, considering old school furnaces could use double or more.

Like stihly said, I was comparing to the Yukon, and to make matters worse, a highly optimized Yukon, WAY miserly on wood compared to stock...now if I could only get it to be as user friendly as the Tundra, I'd really have something!

 

[JRHAWK9]

The one thing they definitely got right with this thing is the whole marketing it towards the do-it-your-selfers. Maybe they should at least include instructions for all the fabricating and tweaking one needs to do in order for it to be useful.

 

[sloeffle]

I got the idea for the one I made from that website I linked to earlier today.

Spent some time on that site yesterday and watched their YouTube video. Pretty cool stuff. Wonder why you need the various different configurations ? My assumption is that one design extracts heat better in certain situations than others.

What are your thoughts on making it the whole length ( 4' as a guess ) of the whole middle flue pipe ?

 

[brenndatomu]

What are your thoughts on making it the whole length ( 4' as a guess ) of the whole middle flue pipe ?

At 24"(ish) it is pretty much full length...could get a couple more inches I suppose

 

[maple1]

I like that hillbilly turb.

You could easily add or subtract pieces to it as needed to tune your draft & temps as needed.

Unless they're all welded in place. Are they all welded in place? If not you could just slide them on & off.

Ingenious.

 

[sloeffle]

At 24"(ish) it is pretty much full length...could get a couple more inches I suppose

I forgot that the Tundra is set up a little different than the earlier Caddy's. My cold air return actually goes over the middle pipe on my furnace.

 

[brenndatomu]

Are they all welded in place?

Yeah

 

[brenndatomu]

The one thing they definitely got right with this thing is the whole marketing it towards the do-it-your-selfers. Maybe they should at least include instructions for all the fabricating and tweaking one needs to do in order for it to be useful.

Well, I think "turn key" wood burners are boring...so there!

 

[brenndatomu]

I forgot that the Tundra is set up a little different than the earlier Caddy's. My cold air return actually goes over the middle pipe on my furnace.

Interesting, didn't know that. The new Caddys are now the same setup as Tundra though...(or vice-versa actually)

 

[Buzz Saw]

Would auger flighting work as turbs? Auger flighting can be found pretty easily in an agricultural community. It wouldn't even need to be new. Find some used flighting and install. If flighting is to restrictive sections could be cut out to allow more flow.

 

[brenndatomu]

Would auger flighting work as turbs? Auger flighting can be found pretty easily in an agricultural community. It wouldn't even need to be nee. Find some used flighting and install. If flighting is to restrictive sections could be cut out to allow more flow.View attachment 171390

I've seen some DIY boiler guys use that...

 

[laynes69]

There's now an add-on return plenum for the Caddy's that allows them to be setup the same as the older versions.

 

[DoubleB]

Well @brenndatomu inspired me with this talk about turbulators, so I had to try.

In my basement I quickly spotted a 5.25” long chunk of spare 6” diameter black stove pipe, that unfolds to a circumference of about 19”. I used tin snips and cut it along the black lines shown in this drawing. A couple shots of CAD to give an idea of the intent. Many chances for the fins to catch air at the center and bring it to the HX tube surface, but without blocking the ability of the gases to pass through to the flue.

The fins were easy to bend to shape with my (gloved) hands, and I gave the piece a twist between each stage of fins. I test-fit it into a scrap piece of 6” ductwork, no problems. Finally, it slid into place very easily. The HX cover is held in place with a bolt (shown) that obscured a straight shot into the HX tube, but this redneck turbulator easily flexed around it.

I just got it installed 15 minutes ago, so no news yet. We’ll see if I can tell a difference.

It’s quite crude, but it was worthwhile because it was easy to do, easy to adapt the design (or do over) if I wanted to, required almost no tools or skill using cheap and available material, and will make an excellent addition to my neighbor’s windchime collection if I don’t want it.

Plus, it should be just as easy to do the same for the 2 outside tubes if I desire, even though their diameter is smaller.

Anyways, maybe this will encourage someone to try who is hesitant that great skill or materials or welding would be required.

 

[brenndatomu]

Well @brenndatomu inspired me with this talk about turbulators, so I had to try.

In my basement I quickly spotted a 5.25” long chunk of spare 6” diameter black stove pipe, that unfolds to a circumference of about 19”. I used tin snips and cut it along the black lines shown in this drawing. A couple shots of CAD to give an idea of the intent. Many chances for the fins to catch air at the center and bring it to the HX tube surface, but without blocking the ability of the gases to pass through to the flue.

The fins were easy to bend to shape with my (gloved) hands, and I gave the piece a twist between each stage of fins. I test-fit it into a scrap piece of 6” ductwork, no problems. Finally, it slid into place very easily. The HX cover is held in place with a bolt (shown) that obscured a straight shot into the HX tube, but this redneck turbulator easily flexed around it.

I just got it installed 15 minutes ago, so no news yet. We’ll see if I can tell a difference.

It’s quite crude, but it was worthwhile because it was easy to do, easy to adapt the design (or do over) if I wanted to, required almost no tools or skill using cheap and available material, and will make an excellent addition to my neighbor’s windchime collection if I don’t want it.

Plus, it should be just as easy to do the same for the 2 outside tubes if I desire, even though their diameter is smaller.

Anyways, maybe this will encourage someone to try who is hesitant that great skill or materials or welding would be required.

View attachment 171404 View attachment 171405 View attachment 171406 View attachment 171407 View attachment 171408 View attachment 171409 View attachment 171410

Dang it man! That is some fo-real modern art! And your just gonna soot it all up!
That is a good idea using light gauge metal, at least to test designs anyways. I 'spose I went heavier than I would have had to.
Did you model the airflow across that? Not sure after a quick study session what the flow path will look like exactly

 

[DoubleB]

fo-real modern art!

No kidding! I'm still not sure if it looks beautiful or hideous. Maybe that's art. (I've never really understood "art").

Anyways...

Did you model the airflow across that? Not sure after a quick study session what the flow path will look like exactly

No formal airflow model. I might be a geeky engineer, but I don't currently have that much ambition for an analysis that might marginally improve things beyond what I rigged by a total of 19 splits over the course of a winter. The general idea is that the fins near the center scoop air from the center towards the outside, depositing those gases at the inlets of the next fins downstream which are on the outside and curved in the opposite direction, further mixing the gases. (The CAD doesn't show this quite accurately, but you can make it out from the as-built pictures on the countertop.)

Well, gotta go load the overnight...