Everything Drolet Tundra - Heatmax...

[DoubleB]

A caddy, max caddy or either Kuuma could be made to work with the appropriate spacing off the floor.

Very smart for thinking ahead...

I figure my flue temp monitoring keeps firebox temps under control so I'm less likely to have cracking issues.

If I remember correctly you heated 3400 sq ft with your 1st Tundra and ran your temp control from day 1 without any cracking problems. Looks like your partial firebrick can only help.

 

[3fordasho]

I've noticed something interesting on both my Tundra installs - when the firebox is heating up but before the fan kicks on, one of the 8" outlets will be warm and the other cold.
Since my second install just dumps into the main building above a small office, I went up there and sure enough the warm pipe was dumping warm air out, but the other was sucking cool air down to the exchanger area. I would have expected both pipes to be warm and cool air coming in thru the filter box.... I guess the supplied 1" filter is enough to prevent gravity flow?

I guess that's why I 've never seen a gravity system with filters in it.... I wonder what happens with the wood furnaces that have only 1-8" (or larger) outlet?

 

[DoubleB]

the warm pipe was dumping warm air out, but the other was sucking cool air down to the exchanger area.

That's interesting. I wouldn't have anticipated that, but I guess it makes sense if the 8" outlets are for separate ducts and at least one has enough vertical rise. I haven't noticed that happen to mine, FWIW. I intentionally dumped both of my outlets into a plenum right away (picture in post #22) in order to have identical pressure drop, and thus the same cooling through each side of the firebox. Doing so probably also mitigates that chances of what you are seeing.

Another reason it's interesting is because it makes me wonder how much longer (if any) it takes your blower to kick on. If you have 60 deg air from the shop coming into the top of the plenum from one "outlet", you might have 180 deg air going back out the other outlet and your blower snap disk in the middle might still only register the average of 120F and not kick on. I don't imagine you've had that problem otherwise you would have reported it. But we've seen every few weeks or months someone will appear asking why their blower isn't turning on with a full fire. Have you noticed anything along these lines that might add to our knowledge base here?

I would have expected both pipes to be warm and cool air coming in thru the filter box

Maybe because the return air is inside your office? Do you still get air coming into one of the outlets if you leave your office door open?

 

[STIHLY DAN]

[quote="DoubleB, post: 1972547, member:
Maybe because the return air is inside your office? Do you still get air coming into one of the outlets if you leave your office door open?[/quote]
This is exactly it. furnace rm in a negative pressure, heated space in an over pressurized state.

 

[3fordasho]

That's interesting. I wouldn't have anticipated that, but I guess it makes sense if the 8" outlets are for separate ducts and at least one has enough vertical rise. I haven't noticed that happen to mine, FWIW. I intentionally dumped both of my outlets into a plenum right away (picture in post #22) in order to have identical pressure drop, and thus the same cooling through each side of the firebox. Doing so probably also mitigates that chances of what you are seeing.

Another reason it's interesting is because it makes me wonder how much longer (if any) it takes your blower to kick on. If you have 60 deg air from the shop coming into the top of the plenum from one "outlet", you might have 180 deg air going back out the other outlet and your blower snap disk in the middle might still only register the average of 120F and not kick on. I don't imagine you've had that problem otherwise you would have reported it. But we've seen every few weeks or months someone will appear asking why their blower isn't turning on with a full fire. Have you noticed anything along these lines that might add to our knowledge base here?




Maybe because the return air is inside your office? Do you still get air coming into one of the outlets if you leave your office door open?

I'd say the blowers on both installs work as intended - usually starting with in 15-20 minutes from a cold start, less on a reload, then running continuous for several hours or more depending on load size.

The office install is with in a few feet of a wide open 32" door and one of two windows open to the rest of the building. So return air flow was not restricted.

In the house install both 8" ducts dump into the same propane furnace plenum, yet one will be warm, other cool when the tundra blower is not running.

 

[DoubleB]

In the house install both 8" ducts dump into the same propane furnace plenum, yet one will be warm, other cool when the tundra blower is not running.

Huh, I'm stumped and curious. I've never noticed that on mine, and frequently noticed both warming equally, but I will pay closer attention this fall.

What about the end of a burn cycle when the blower cycles on/off for 1-2 hours on coals--Do you get cold air coming into one of the outlets then? Or is it just at startup?

More so, what happens if you pull the plug to simulate a power outage? My concern would be that you might not get good cooling in an outage if your cold air is coming in from the top.

If you don't think it's a problem, then it's not my place to try to diagnose anything. It just strikes me as not optimal, and potentially problematic because I would imagine that SBI probably hasn't seen that in their testing. Although I have absolutely nothing but speculation upon which to base that statement! I just know that when I can't explain why something unusual happens, I often assume that I have a problem in the making.

 

[brenndatomu]

I've noticed something interesting on both my Tundra installs - when the firebox is heating up but before the fan kicks on, one of the 8" outlets will be warm and the other cold.

Are both pipes identical in length and shape? And do you have dampers in them for setting static pressure, doesn't appear so, dunno if that would affect gravity heating any though?

Speaking of the filter blocking gravity flow...
I noticed a couple years ago that the area in my Yukon furnace where the filter goes is wider than the filter by at least an inch. I called Yukon about it, they said that is for airflow during power outage. They said even better was to remove the filter if you are home. They had to have the gap to be able to be UL certified to run during power outage...I think they said the they are the only ones that are (UL certified for power fail) Not all the return air gets filtered but most does I would guess.
Point is, maybe that is why SBI made the gaps so wide where they stamped the blower box for cutting out the side where you want the filter to be. The other two sides still have all the holes for a lil airflow during power fail?

 

[brenndatomu]

It would be an interesting experiment...build the fire on one side of the firebox more so, (from a cold firebox) see if you can make the heat go to the duct on the fire side, I bet it does

 

[3fordasho]

Are both pipes identical in length and shape? And do you have dampers in them for setting static pressure, doesn't appear so, dunno if that would affect gravity heating any though?

Speaking of the filter blocking gravity flow...
I noticed a couple years ago that the area in my Yukon furnace where the filter goes is wider than the filter by at least an inch. I called Yukon about it, they said that is for airflow during power outage. They said even better was to remove the filter if you are home. They had to have the gap to be able to be UL certified to run during power outage...I think they said the they are the only ones that are (UL certified for power fail) Not all the return air gets filtered but most does I would guess.
Point is, maybe that is why SBI made the gaps so wide where they stamped the blower box for cutting out the side where you want the filter to be. The other two sides still have all the holes for a lil airflow during power fail?

On both installs the outlet runs are identical on each furnace and both use the right and left outlets, not front or back. No dampers. Next time I fire one up I am going to pull the filter out and I bet it will gravity flow up both pipes just fine.... I think the filter is just enough restriction that the air finds it easier to flow down one outlet and up the other.

 

[3fordasho]

I've been getting inquires about the flue temp control add on I've installed on my first and now second tundra install- much was detailed in posts 261 and 306 of this thread.
I never detailed how I set all the parameters/settings in the Omega temp controller so here they are:
code - description - setting
HIAH - high limit alarm - 3000 (default setting)
LoAH - low limit alarm - 255-275
HdAL - deviation high alarm - 3000 (default setting)
LdAL - deviation low alarm - -999 (default setting)
Loc - parameter lock - 808 (unlocks rest of parameters)
AHYS - alarm hysteresis - 100
AOP - alarm output assign - 111 (default setting)
CtrL - control mode - onoF
Act - n/a - rE (default setting)
P - proportion band - 30 (default setting)
I - time of integral - 100 (default setting)
d - time of derivative - 50.0 (default setting)
Ctl - control period - 20 (default setting)
CHYS - control hysteresis - 200
InP - thermocouple type - 5 (selects J-type thermocouple)
Scb - input shift - 0 (default setting)
FILt - pv input filter - 1 (default setting)
Fru - input hz and C or F - 60F (60 hz , F)
SPL - low limit of set value - 0 (default setting)
SPH - upper limit of set value - 1000


so out of all these there are a few you may want to adjust depending on your install.

First there is the temp SV (set value) that is always displayed by the green LEDs. I've got mine set at 625f. This is the value I've decided I don't want my flue temps to exceed. Once the flue temps hit this value the controller closes the air inlet damper.
When does it re-open? that is controlled by CHYS control hysteresis and I set mine at 200 - means the air inlet opens back up at 625-200=425f. Factory default for is 2 - don't leave it there you'll cycle your damper motor to death. You may desire to play with these settings to fine tune operation. Keep in mind that there is usually something else calling for the air inlet to be open for flue temps to hit the high end, either the reload timer, or thermostat, or if someone has inadvertantly left the manual damper switch in the open position.

Next there is the LoAH low limit alarm, I've currently got mine set at 255f. Say you cold started your furnace or just reloaded on some coals. You set your timer to 25mn to hold the damper open to get the new load hot so secondary burn can occur- but 25 mn wasn't really enough, secondary burn dies off and flue temps drop to 255f. At this temp secondary burn is probably not happening and the furnace is probably smoking. The low temp alarm kicks in and opens the air inlet. How long does it stay open?, that depends on your AHYS alarm hysteresis setting and I've got mine set at 100 - so the damper closes again at 255+100=355f. Again these settings you may want to play with to tune your furnace operation.

 

[Matt78]

First off I would like to say this site is great with a lot of great knowledgeable people. Thanks for the help setting up my install.(not done yet!). I'm going to do the setup 3fordasho described above. That is a lot of info to take in. Today I also added fire brick that doubleb did in an earlier post. Hoping to minimize or just eliminate any cracking.

 

[brenndatomu]

I've been getting inquires about the flue temp control add on I've installed on my first and now second tundra install

Imitation is the sincerest form of flattery...

First off I would like to say this site is great with a lot of great knowledgeable people. Thanks for the help setting up my install.(not done yet!). I'm going to do the setup 3fordasho described above. That is a lot of info to take in. Today I also added fire brick that doubleb did in an earlier post. Hoping to minimize or just eliminate any cracking.

View attachment 162415 View attachment 162416 View attachment 162417

Nice work!
I really believe those two mods are gonna make for a durable, sweet running furnace!

 

[Wisneaky]

This is from a member on another site.

Hello everybody I have received information from sbi about the extra firebrick on the newest models. If you go on drolets website and look at the manual you will see the new brick they added to the front. I have been sending emails back and forth to sbi about the added brick. Finally I got in touch will somebody knowledgeable and they let me know that a updated kit for our older models will be available in 3 to 4 weeks. They said to just email them around that time and they will ship the update kit out.

 

[Matt78]

Figures! Lol

 

[DoubleB]

Today I also added fire brick

Hey Matt,
That's nice looking work. Given that you also added firebrick on the bottom, you should be extra likely to avoid any cracking. Judging by pictures on here of the cracks, I think the sides are the most important to protect, but I'm sure it helps to put it on the bottom too. Too bad you/we didn't know about the retro kit from SBI, but I doubt their kit will have the firebrick on the bottom so you're still better off.

 

[brenndatomu]

Figures! Lol

Yeah, and nothing like waiting 'til the last minute! Better late than never I 'spose.
Wonder if they will track people down or make you chase them for a kit?

Kinda wish I hadn't wasted the time n money to do the SS shield now...oh wells

 

[DoubleB]

Wonder if they will track people down or make you chase them for a kit?

One would hope so, but I doubt it by now.

Kinda wish I hadn't wasted the time n money to do the SS shield now...oh wells

I also suspect they wouldn't send the kit to a furnace that's been "rescued".

But I'd love someone to prove me wrong on either of the above!

 

[brenndatomu]

I also suspect they wouldn't send the kit to a furnace that's been "rescued".

Oh, I have no doubt about that. Not for warrantied stoves...
I would just buy a box of bricks, do my own, just seems simpler than what I did. I will still probably add the brick across the bottom, that's a good idea

 

[DoubleB]

I would just buy a box of bricks, do my own, just seems simpler than what I did.

Oops, my misunderstanding. I see what you were saying.

 

[Matt78]

Hey thanks guys. The drawing you provided doubleb was spot on and made it 100% easier! I'm going to go with what I have and see what happens. I didn't plan on the bricks at the bottom. Those where scrap pieces and I figured I'd throw em in there. I read somewhere that on the new furnaces they changed the style of brick. I wonder if they would send the newer style bricks for the whole furnace? The bricks that came with the furnace seem kinda cheep and light weight.

 

[laynes69]

The lightweight bricks while lighter and not as durable, they have better insulation properties which aid in better combustion. The higher the firebox temperatures, the cleaner the burn and higher heat output.

 

[DoubleB]

Matt78, glad the firebrick worked out so well for you.

I noticed in your pictures that your furnace's firebrick looked quite gray, whereas the firebrick in mine was somewhat pink. So perhaps they have changed it.

I was just at Menards and noticed they are selling the Tundras for $1599 again. (But their display unit still doesn't have the firebrick in the front.)

 

[brenndatomu]

I was just at Menards and noticed they are selling the Tundras for $1599 again. (But their display unit still doesn't have the firebrick in the front.)

Our local store has had the same unit on display for a couple years. They (store employees) probably have no idea anything has changed

 

[Buzz Saw]

Our local store has had the same unit on display for a couple years. They (store employees) probably have no idea anything has changed

Not the only thing Menards employees are clueless on....

 

[brenndatomu]

Not the only thing Menards employees are clueless on....

Einsteins compared to Lowes and HD though...and much less attitude