Everything Drolet Tundra - Heatmax...

[Builderml]

I got around to reading the manual this morning, The manual states as follows:
Fan on 140*
Fan off 120*
Damper door closes 160*

 

[laynes69]

That's odd, a false top. There's where alot of heat exchange occurs. That would explain a lack of heat.

 

[Matt78]

Bullderml. I could get a pic when I get home on Sunday for Brenn. Mine just has the filter box on it.

A lot of good info to read through on the last few pages. Thanks and happy thanksgiving!

 

[brenndatomu]

That's odd, a false top. There's where alot of heat exchange occurs. That would explain a lack of heat.

Yeah, kinda, there is no space between them, but definitely two layers. I would guess it is there as a flame shield.
That's why I was thinking maybe that was where my heat exchange loss was occurring (if it turned out to be in need of a good cleaning) because on a stove, the top is the main "heating surface", but as I said before, it is obvious that they aren't super concerned with capturing heat directly from the firebox since it is completly insulated in some form or fashion. The bottom part is completly covered in two layers, firebrick and 1/8" thick ceramic insulation blanket behind that. Then the "two ply" metal top above the baffle.
Also, if they were concerned about capturing heat from the firebox top, they would tell you in the manual to clean that area regularly.
I assume that the newer Tundras, like builderml's machine, has the same two ply top, and he is not lacking for heat exchange...

 

[brenndatomu]

Did you open your dampers? What does your tie ins look like?

Yup, blower amps went up, temp went down. (I have the unit plugged into a Kill-A-Watt monitor)(yeah, I like gadgets and gauges )
I am using the two side duct holes as recommended, I have two 8" pipes straight up into the main trunk line. I have the Yukon blocked off so the airflow can't back feed.

 

[STIHLY DAN]

Yup, blower amps went up, temp went down. (I have the unit plugged into a Kill-A-Watt monitor)(yeah, I like gadgets and gauges )
I am using the two side duct holes as recommended, I have two 8" pipes straight up into the main trunk line. I have the Yukon blocked off so the airflow can't back feed.

Open return, or ducted?

 

[brenndatomu]

Open return, or ducted?

I have the filter access door off of the Yukon and the filter of the Tundra is facing it, about 3' away. I have checked the air temp of the air down by the floor in the furnace room VS the return air from the duct, 1 or 2 degrees difference. A couple days ago I remember going upstairs and thinking that it was warmer in the basement than upstairs

 

[brenndatomu]

Thanks and happy thanksgiving!

Thanks! Happy Thanksgiving to y'all too.
We are chillin at the in-laws for a couple days...literally. Gas heated 5000 sq ft stone mansion...f-f-f-freezing here. Much colder here than at home, even when we are using the Tundra!

 

[STIHLY DAN]

I have the filter access door off of the Yukon and the filter of the Tundra is facing it, about 3' away. I have checked the air temp of the air down by the floor in the furnace room VS the return air from the duct, 1 or 2 degrees difference. A couple days ago I remember going upstairs and thinking that it was warmer in the basement than upstairs

Did you happen to look at the insulation on the jacket? If the insulation gets loose it can block air flow when the fan comes on.

Also, I am a little pissed at you tonight. I spent the day busting butt cutting down trees and bringing them home. After all this talk of dirty heat exchangers and it being 55* out, tonight I cleaned mine. Every muscle in my body was either screaming or cramping and there I was cleaning a heat exchanger because you guilted me into it. With the little wood that I have I cant spare a BTU. I did find a few bird skeletons. I'll be over it tomorrow.

 

[brenndatomu]

With the little wood that I have

EDIT: I just realized that this quote makes it look like I'm laughing at your manhood... What I meant was, I was pickin up on your sarcasm of acting like you are out of wood, when I know you are building "lumber mountain", what you cuttin for winter '20-'21 today?

 

[brenndatomu]

Did you happen to look at the insulation on the jacket?

Haven't taken the cabinet apart...yet.

If the insulation gets loose it can block air flow when the fan comes on.

There is a bunch of air flow coming out when I remove one of the duct connector block off plates, actually a surprising amount for the fan being on "low". And I didn't hear any flapping or buzzing like I would expect if there was loose insulation

After all this talk of dirty heat exchangers and it being 55* out, tonight I cleaned mine.

You should post pics of the ridiculous amount of nothing that comes out of a Vaporfire when you clean it, most of these guys have probably never seen anything like it out of a wood burner. I'm gonna post my cleaning pics...you post yours! If you don't want to put them on a Tundra thread then put 'em on a Kuuma thread and then just drop a link here. The only area that I found that had the white powder that you always get was the front 3/4 of the firebox top, above the baffle.

 

[brenndatomu]

OK, we're back home now and I'm thawing out in front of the stove after "chillin" at the inlaws for Turkeyday. Anyways, here is the firebox and HE cleaning pics I promised. As a reminder, this is a ~3 YO furnace and I have no idea if this area has ever been cleaned before or not.
Front 3 tubes and the baffle removed, looking in the door and up to the right
In the back on the left, the rectangular hole is the opening to left HE connector
Left side
Looking in the door and up
This is after I cleaned some, I wanted to try to show how much buildup there was. This is looking back at the backside of the front of the firebox, at the top. Actually, you are looking at the heat shield on the back of the damper door intake box there at the bottom of the pic.

File is full for this post, more pics to come...

 

[brenndatomu]

...cleaning pics continued.
In the back, to the left
...to the right
After cleaning. Notice the black spots around the edges where the welds for the doublewall top are
Here is a closeup of the left HE connection, from the back, camera pointed to the left and back to the front a bit. This is where I noticed the double wall top, you can see the edge hanging down just a bit there. And that black lump (center top) is the weld...
After cleaning, in the back, to the right, once again notice the weld in front of the HE hole for the doublewall, and you can see the edge of the doublewall there again, right where the tan meets black

 

[brenndatomu]

...more pics
The center HE tube after cleaning the firebox, but before cleaning the tube itself.

 

[JRHAWK9]

Because I'm not getting duct temps as high as yours. The temps I stated were 2' above the furnace, I haven't checked duct temps further down the line, or at the registers, I probably should though. I only get temps above 100* while the damper is open, or maybe for a while after the damper closes during the intense part of the secondary burn. Once that is over we are definitely under 100* duct temps right above the furnace. Like I said before, If I had 110-120* duct temps (consistently) I would have no problem heating the place with that, but 90s, even 80s (remember, I have the old style fan switch in the back) during the end of the burn cycle are barely cuttin it, and the weather is pretty mild, so I don't have a lot of faith that this is gonna work out when the temps drop. I guess I need to move the fan switch, see if that makes any real difference, one thing at a time though.

Your duct temps aren't all -that- much lower than my plenum temps though, although mine are more consistent based upon what you said above. My plenum temps 31 inches above the top of the furnace are always 100°-110° during a burn. I'd say 80% of the time they are right around 100° when the furnace is on low. The blower shuts off when the temp gets down to 95°

I think having consistent 110°-120° plenum temps are unrealistic (if you are looking for your blower to be running constantly and not cycling in order to keep up those temps), as my LP FURNACE mainline duct temps only 8' from the LP FURNACE are only getting up to those temps.....lol My wood furnace duct temps at this same location are usually 1-2° cooler than they are at the plenum 31" above the wood furnace as mentioned above.

Got home today from the family farm, the house was 63°. I turned the LP furnace on and let it run awhile while I made a fire in the Kuuma. My LP duct duct temps 8' from the furnace only reached 110° this time running for about 15-20 minutes. This is a 75,000 BTU LP furnace. For me, if I were running consistent 110°-120° plenum temps with the Kuuma it would be like running my 75,000 BTU LP furnace 8-12 hours straight.

 

[STIHLY DAN]

That HE opening seems/looks like 6X6, is this true? If so, that is the issue and no fix for that. Also explains a lot.

 

[brenndatomu]

That HE opening seems/looks like 6X6, is this true? If so, that is the issue and no fix for that. Also explains a lot.

Where? The holes from the firebox or the clean out door? The holes from the firebox are probably 4.5" x 3". The side HEs are about 4.5" diameter and the center one is 6".
So what exactly are you pointing out as the issue here? I'm cornfused(er)

 

[Builderml]

So after nearly 6 weeks of burning and yesterday being near 60 I decided to give the chimney and H.E and good cleaning, I used a 6" poly brush and 24' of rod attached to a cordless drill. After cleaning the chimney I got about 4 cups of black powder. I guess that's good but I really have no idea. It was all softwood burned during this time. So is that good or bad? Dry black powdery substance. I took the same 6" poly brush and ran it in all 3 H.E. tubes. It's tight on the smaller left and right tubes but did a really nice job cleaning everything up. So I do recommend using the 6" poly brush attached to a 4' rod to clean the H.E. tubes.
I also took the first 3 secondary burn tubes out and removed the baffle, wasn't anything I really had to clean in that area but still wanted to see what it looked like in there. I did notice the second layer of steel that Brenn has been talking about on the top of the firebox. When Brenn asked me to take a picture of how the blower motor is attached it came to my attention that my dumb axx also does not have access to the fan speed control. Guess I do need to make an access panel to get in there. Not sure what I was thinking but I figured the fan speed control was located in the gray box located at the top edge of the furnace so when I opened it up to take a look I had a few choice words for that smart move on my part. That's pretty much it for now. Hope everyone had a great Thanksgiving.

 

[brenndatomu]

also does not have access to the fan speed control. Guess I do need to make an access panel to get in there

Thanks for the cleaning info builder, 4 cups doesn't sound too bad to me, but I dunno?
As far as fan speed access, the filter kit comes with two sheet metal panels that can be screwed onto either side or the back. You have to cut out the factory panel (it's already slotted, you just have to finish the cut) then one of the 2 panels can be screwed on over the hole...unless your return air duct attaches to the right side (same side as the "controls" box) then you are on your own for access. Don't worry about getting in there just for my sake, Mat78 said he'd get the pic I was after, thanks though!

 

[DoubleB]

I have the unit plugged into a Kill-A-Watt monitor

Hey Brenn, here are some more numbers for comparison:

I'm 90 minutes into a burn, full load mostly box elder and a couple small elm splits.

I just lost enough offgassing to maintain the secondaries, and my return temp was 68F and air jacket temp next to limit switch was 115F. I measure air jacket it by removing the screw for the unused cover for the side outlet on the top of the furnace, and putting my DMM thermocouple into the hole. The hole is about 1 inch away from the damper cutout snap disc.

Fan speed 1 draws 200 Watts (with the damper closed, the damper draws another 9 Watts if energized).

So, with a stabilized heat output with the secondaries after the damper was closed for quite a while, 200W blows enough cfm for a 47F temp rise.

What is your wattage and temp rise in those conditions?

Thanks for the nice pictures too.

 

[DoubleB]

I had a few choice words for that smart move on my part.

You and me both. I think all of us can find a thing or two we wish we would have done differently. And usually go back and modify it. Just good experience is all.

Your 4 cups sounds pretty good to me. I'm sure someone has done better, but not me.

 

[STIHLY DAN]

I'm 90 minutes into a burn, full load mostly box elder and a couple small elm splits.

I just lost enough offgassing to maintain the secondaries,

How long was your over all burn time on that load?

 

[STIHLY DAN]

Where? The holes from the firebox or the clean out door? The holes from the firebox are probably 4.5" x 3". The side HEs are about 4.5" diameter and the center one is 6".
So what exactly are you pointing out as the issue here? I'm cornfused(er)

My bad buddy. Reread what you wrote, I see there are 3 openings not one. So what does the he look like? I am envisioning 3 square vertical columns in the rear that then send 3 round cylinders to the front mating into 1 box.

 

[brenndatomu]

My bad buddy. Reread what you wrote, I see there are 3 openings not one. So what does the he look like? I am envisioning 3 square vertical columns in the rear that then send 3 round cylinders to the front mating into 1 box.

You're close. 2 vertical rectangular columns (pretty short) that connect the 2 smaller side HEs to the firebox. The smoke/gasses travels forward to the cleanout box seen in my last pic, where they then converge together into the center HE, then out the back into the stovepipe

 

[DoubleB]

How long was your over all burn time on that load?

Started the fire 5 hours ago, damper closed ever since it got going. 2100 sq ft farmhouse is still 4F warmer than this morning, and the coals are still cycling the blower.

20F outside, sunny, not much wind. I project I'll start another load about 4-5 hours from now.