Everything Drolet Tundra - Heatmax...

[KC Matt]

OK, this is the schematic. Keep in mind I'm no engineer and this is the first use of this software so this may not be technically correct, but it's accurate. For one thing there is no option to show how the Johnson Control box actually works, but it's a double throw single pole switch so that's what I used. Also, there is no reason to ever buy a 419 box because the 421 is much improved. And there is no reason to buy a controller powered by 12VDC but that's what the 419 is This was a learning process for sure.

Over the last year I've spent dozens of hours watching this furnace cycle, tweaking the settings over and over. These are the settings that worked best:

Damper control:

Set point adjusted for heat demand
Differential 2*F
ASD no
OFS 0
Sensor failure 0 (Closed)

Blower on/off controller

On 97*F
Off 83*F
Sensor fault 1 (blower on)
ASD 2 minutes

High/low blower speed controller

on 91(low speed)
off 93 (high speed)
Sensor failure 0 (high speed)

Model A421 ABC-02

 

[KC Matt]

Here you can see the sealant around the heat exchanger. There was an 1/8" gap around most of this opening. I used 3M Fire Block FB136

 

[Possumstomper]

Hello all. Been a lurker for little over a year on this thread. Bought a tundra fall before last just now getting around to the installation. After reading some of this thread about 60 pages. I have come away with some great info, but I do have a question. I have aquired a mypin Ta4 controller after reading brenndatomu's mention of but am unsure how to wire it correctly to control my damper. I've got the controller and a thermocouple no relay

 

[KC Matt]

Hello all. Been a lurker for little over a year on this thread. Bought a tundra fall before last just now getting around to the installation. After reading some of this thread about 60 pages. I have come away with some great info, but I do have a question. I have aquired a mypin Ta4 controller after reading brenndatomu's mention of but am unsure how to wire it correctly to control my damper. I've got the controller and a thermocouple no relay

I'm not familiar with that controller, but to activate the damper you just connect the two terminals on the back of the furnace, in this case with the controller. No relay involved there; that is more for the blower speed controller. I'd suggest you also install a controller for the blower on since the factory switch lets the fire get very hot before coming on. I suspect that's a big part of the cracking issue and it wastes an awful lot of heat.

 

[Possumstomper]

I'm not familiar with that controller, but to activate the damper you just connect the two terminals on the back of the furnace, in this case with the controller. No relay involved there; that is more for the blower speed controller. I'd suggest you also install a controller for the blower on since the factory switch lets the fire get very hot before coming on. I suspect that's a big part of the cracking issue and it wastes an awful lot of heat.

Yeah I'm just now getting into the part of this thread where there is talk about variable speed motors, controllers ect. Wish I would have read this entirely last year

 

[brenndatomu]

I have aquired a mypin Ta4 controller after reading brenndatomu's mention of but am unsure how to wire it correctly to control my damper. I've got the controller and a thermocouple no relay

Here is a wiring diagram that @3fordasho posted, I basically used the same setup except wiring in a relay to "flip" the contacts of the Mypin...it had (I don't recall now) NC or NO, and I needed the other...wiring in a DPDT relay allows you to have either NC or NO contacts.
https://www.hearth.com/talk/threads/everything-drolet-tundra-heatmax.140788/page-13#post-1926802

I'm not familiar with that controller, but to activate the damper you just connect the two terminals on the back of the furnace, in this case with the controller. No relay involved there; that is more for the blower speed controller. I'd suggest you also install a controller for the blower on since the factory switch lets the fire get very hot before coming on. I suspect that's a big part of the cracking issue and it wastes an awful lot of heat.

The Mypin is used as a firebox/flue temp controller only.
I don't recall now if I posted a wiring diagram on the blower speed controller that I added later...wiring was pretty much right from their directions...more or less...these speed controllers are meant for use on AC compressors, so the directions show that, but it is still more or less the same electrically.
Just an FYI on the speed controllers...don't get to nuts with them...turning them down too far could burn up the motor...although very unlikely in this application (IMO) because the load on the motor drops to almost nothing at the lower speeds. But I still wouldn't go under 60-65%...really no reason to go any lower anyways because it is moving only very small amounts of air at this point. Speed controlling these blowers this way I'm sure is not recommended by the manufacturer of the blower, (and Drolet I'd bet) but I have used it the better part of 2 seasons now with no issues. Just be aware that even though it may not blow up the blower motor right away...or even anytime soon, it probably isn't going to help motor life, long term...

 

[Possumstomper]

Thanks for the info. That makes sense now about the relay. Gotta check that mypin and see how it's setup. I'm still reading through the thread and gaining important info.

 

[TDD11]

I guess I need to look in to these variable speed fan controllers. Do you guys highly recommend them? What exactly are the benefits again?

I love the damper controller that I installed with the guidance of this forum, I can't imagine not having it.

 

[brenndatomu]

I guess I need to look in to these variable speed fan controllers. Do you guys highly recommend them?

It made a huge difference for me, but my Tundra just didn't seem to work well, as evidenced by this thread. The constant fan on/off cycling drove me crazy, and I knew I was losing heating at the end of a burn when the fan would kick off and there just wasn't quite enough temp left to kick it back on...that's where the speed control shines, it keeps the blower scouring any available heat and putting it to the house for much longer...low BTU output, but better than none! Made a big difference for me...and got rid of the cycling...I hate that!

 

[JRHAWK9]

It made a huge difference for me, but my Tundra just didn't seem to work well, as evidenced by this thread. The constant fan on/off cycling drove me crazy, and I knew I was losing heating at the end of a burn when the fan would kick off and there just wasn't quite enough temp left to kick it back on...that's where the speed control shines, it keeps the blower scouring any available heat and putting it to the house for much longer...low BTU output, but better than none! Made a big difference for me...and got rid of the cycling...I hate that!

Like you already know, it made a noticeable difference for me too, as I added one to my Kuuma last winter. I set it up a bit differently than you guys do on your Tundra's, but it still made a difference. I have my snap switch controlling the on/off of the whole system. It shuts it off at ~104° - 106° plenum temps at ~65VAC. This leads to some pretty low air volumes, but increased supply temps, which my house seems to really like. I think it increases the furnaces delivered efficiency's by extracting more usable BTU's out of the furnace near the end of the burn by not moving such a high volume of air so fast which just leads to a high volume of cooler air being delivered as opposed to a much lower volume of warm air.

I may try lowering my snap switch 5° to lower my blower cutoff some, but then I will have to raise the blower speed (by way of my variable resistor pot) so that at cutoff I'm not below that 65V. This will increase the overall volume of air being delivered and decrease my overall supply temps. I'm not sure if I would see an improvement or not.

 

[3fordasho]

I guess I need to look in to these variable speed fan controllers. Do you guys highly recommend them? What exactly are the benefits again?

I love the damper controller that I installed with the guidance of this forum, I can't imagine not having it.

I added the variable blower control to both my Tundras and like it a lot. The factory tundra snap switch worked OK on the one in the house, but the shop unit was inconsistent at best and like brenn mentioned the cycling kind of sucks. With the variable speed blower control the fan will run for the duration of the burn, in fact it was still running this morning at 5:30 am after last nights 10pm reload.

It's not necessary to use a snap switch with the blower control but I do use a adjustable snap switch to shut down the blower control at the end of the burn, I find the blower controls I have will run the blower motor very slow before the control itself shuts the motor off - too slowly I feel, so I use the snap switch to shut it down. I think this is my third year with the controls and no motor issues so far.

I have to say with the damper control and blower control this is the slickest wood burning set up I've ever run, very easy to load and go when you are in a time crunch, like every morning before work when you don't have a bunch of time to dink around.

 

[KC Matt]

I guess I need to look in to these variable speed fan controllers. Do you guys highly recommend them? What exactly are the benefits again?

I love the damper controller that I installed with the guidance of this forum, I can't imagine not having it.

My fan speed control is set up different than above, but yes, it makes a difference. Without it, you set the fan on speed 1,2,3 or 4 and it stays on that speed. If you set it on a higher speed, it will cycle the fan on and off frequently during the burn. When the fan is off the heat exchanger is absorbing some heat, but you are losing some of it up the stack.

Conversely if you put the fan on a lower speed, it will run a greater percentage of time, but your supply temp will be very high early in the burn. I have no data to back this up but I feel that more heat would go up the stack even though you would flow less air at a higher temp.

What I like about the variable (2 speed) setup I have is that the fan runs most of the time and produces an even heat which feels better in the house and keeps the temperature more consistent.

The reason I did the 2 speed is that it should be more reliable and that's my #2 priority, only behind safety. Here reliability really is safety. With the 2 speed the motor is always running at full cycle, and it spends about half the time on speed 1 and half on speed 3. If the sensor OR the controller fails, the blower goes to high speed. The Johnson Control boxes are used extensively in industrial applications where reliability is essential. A friend of mine has been designing and installing industrial control systems for 30 years and he guided me towards this setup. He was emphatic that running a single speed motor on a variable control will shorten motor life.

Whether you use the variable speed controller or a two speed setup, you are largely accomplishing the same thing, just in different ways and with different priorities.

In my experience, the other two controls are more or less required where this one is a nice option. The factory on/off switch is totally inadequate and without an automated damper control, the only way the furnace really works is for somebody to stay in front of it, turning the switch on and off all day.

 

[Possumstomper]

First small fire cause I couldn't wait to finish install 100%

 

[KC Matt]

Hope you don't have to open the windows with that barn burner going! LOL. BTW that furnace won't run worth a hoot with a tiny load like that. You need a good amount of BTU to get the furnace to work, along with a good draw on your stack.

When I uncrated my furnace, I started a small fire with no chimney attached and was nervous about how poorly it worked. There is no half way with these things. If you are going to run a Tundra you have to take all of the advice in these 90 pages to heart.

 

[TDD11]

You guys have convinced me. I'm going to order the Totaline P251-0083H control. I will likely have some questions when I dig in to it.

I need to rethink my duct plumbing at some point.. currently the Tundra feeds in to my gas furnace's supply duct. Just as KC Matt does, I put a block off in my gas furnace when using my Tundra, to prevent backflow through the gas furnace. The output of the gas furnace is some oddball size and I can't find a damper for it. In a perfect world, I'd have a damper on it, so that if for some reason I don't come home, the gas furnace will keep the house above 50°F. Not only that, but I need to add a humidifier at some point also.

 

[KC Matt]

You guys have convinced me. I'm going to order the Totaline P251-0083H control. I will likely have some questions when I dig in to it.

I need to rethink my duct plumbing at some point.. currently the Tundra feeds in to my gas furnace's supply duct. Just as KC Matt does, I put a block off in my gas furnace when using my Tundra, to prevent backflow through the gas furnace. The output of the gas furnace is some oddball size and I can't find a damper for it. In a perfect world, I'd have a damper on it, so that if for some reason I don't come home, the gas furnace will keep the house above 50°F. Not only that, but I need to add a humidifier at some point also.

That's the same situation as here. A gravity damper would work on the supply side, but on the return side the only way to automate the changeover is to put an electric damper on the trunk. The damper exists for a price of $350 plus the controller.... it would be well over $500 for those parts. In my case, I'd have to move a wall which would mean reworking hardwood flooring, ceiling texture, ductwork, replacing/reframing a door repainting the living room, etc. easily another $500+ and many hours of labor. Nah, I'll just switch the blockoff plates twice a year.

But yes it does knaw at me.

 

[Possumstomper]

Hope you don't have to open the windows with that barn burner going! LOL. BTW that furnace won't run worth a hoot with a tiny load like that. You need a good amount of BTU to get the furnace to work, along with a good draw on your stack.

When I uncrated my furnace, I started a small fire with no chimney attached and was nervous about how poorly it worked. There is no half way with these things. If you are going to run a Tundra you have to take all of the advice in these 90 pages to heart.

How correct you were. It wasn't worth a piss with that little fire.

 

[Possumstomper]

Ok I feel kinda dumb but could someone post a picture of their wiring diagram for a Totaline P251-0083H head pressure control. Please. I've never been good at electrical period and especially don't have a clue about anything like this. Please help my slow ass

 

[brenndatomu]

Ok I feel kinda dumb but could someone post a picture of their wiring diagram for a Totaline P251-0083H head pressure control. Please. I've never been good at electrical period and especially don't have a clue about anything like this. Please help my slow ass

I'll try to get some pics and write something up...unless someone already has this handy and wants to beat me to it...

 

[Possumstomper]

Last night was first night of actually running stove. It did fair. Kept house at a steady 68 with a medium sized load with windy conditons in the 30's. Definitely a new world for me. I finally got my draft dialed in which helped a bunch. Next on the list is to set fan speed. I originally set it a .20 static pressure verified by my manometer, setting 3 on fan. I'm gonna try to set it lower hopefully to keep a more constant heat instead of the fan cycling all the time. At least till the new controller arrives. So far I'm happy with it especially not having a clue about what I'm doing. Still on the list is to seal ash plug, install/reposition snap discs,front firebrick, bathroom timer and controllers for damper/fan. My stove is #740 still hasn't gotten all the updates. Yes I know I didn't come straight up at minimum 12 inches off stove.

 

[brenndatomu]

Yes I know I didn't come straight up at minimum 12 inches off stove.

The stove pipe looks fine to me. The thing that scares me is the ductwork, you have built the perfect heat trap. If the power goes out right after a reload, that thing will go nuclear with no gravity cooling of the firebox...this setup is not legal with any solid fuel furnace that I know of, or local code, if you care about that. The only solution other than changing the ductwork (which I can only assume isn't feasible?) is to install an emergency heat dump door in that "plenum" on top of the furnace there. It is basically just a door that is held shut by a spring attached to a fusible link...it gets to a certain temp, the link melts, allowing the door to drop open and the furnace to get gravity cooling. I found out this is also the reason that the Tundra blower box has all those slotted holes (don't cover them) so if the power goes out there can be some air pulled in easily...in other words, air that does have to be pulled through the filter...which is pretty restrictive when it comes to gravity air flow. Heck, even my $5000 Yukon furnace has a 1" gap along side the air filter for this very reason...had to be there to pass UL testing I hear.
Here's a link to the only EHD that I know of anymore...
http://www.yukon-eagle.com/FURNACEACCESSORIES/SAFETYHEATDUMP/tabid/200/Default.aspx

 

[brenndatomu]

You will probably find best performance on one of the two lowest fan speeds I'd bet...even if the SP is a little too low

 

[Possumstomper]

Actually have 2 8×14 registers installed in top of ductwork incase of power outage, but yes it wasn't feasible to run any other way. I will sure look at that damper you linked tho. Thank you.

 

[Possumstomper]

I like that dump better. Thanks again

 

[brenndatomu]

I like that dump better. Thanks again

I have a pretty good gravity heating setup and I still installed one of these dumps...makes me sleep better at night if nothing else