# The whole deal for a basement wood furnace



## roofyroo (Jan 30, 2015)

I had a thread on the Hearth Room and was suggested to post in here as my solution is moving towards a wood furnace in my basement.

Previous thread link.
https://www.hearth.com/talk/threads...r-relocate-my-wood-stove.140210/#post-1885613

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*Relevant furnace info from original post doing Option 5*
I'm in Virginia and recently bought a 2 story 2000 sq. ft. house with a basement (additional 1000 sq. ft.) built in 1933. The previous owners left a Hearthstone Heritage 8021 wood burning stove which is located in a corner room of the house which was clearly an additional at some point. This room has a chimney flue as well the 2 flues in each side of the open basement.
The old owners just upgraded their heating system but it is all electric and clearly the unit is not capable of keeping up in the cold - hence the electric bill is sky high - so I'm investigating options.

5. Buy a wood burning furnace, install in the basement, hook it into the HVAC. This option will mean lining one of the chimney's for exhaust.

From my morning's research I understand lining a chimney is not difficult, and several experts over the phone suggested the Z Flex liner. I went up on my roof and checked things out and my chimney flue is approximately 27' so the 30' kit would do.
http://www.supplyhouse.com/Z-FLEX-2ZFLKIT0630-6-x-30-FT-All-Fuel-Stainless-Steel-Liner-Kit
MyRubberNeck says the kit comes with a _Long Snout Flex Ready Tee_
SupplyHouse says the kit comes with a _Stacking Tee
I believe these are both the same but worded differently?_

I see that pretty much everyone recommends *insulation of the lining* if using for wood, and I found this, also from Z Flex - 25' x 6".
http://www.supplyhouse.com/Z-FLEX-2INSKIT0625-6-x-25-Ft-Insulating-Blanket-w-Wrap-Gear-Clamps
_Would I really need to purchase an additional 2' of this so my entire chimney is lined with insulation?_

Total for chimney lining and insulation.
MyRubberNeck - $1015
SupplyHouse - $868

*I wanted to stay below $2000, but if this is a longer term investment then I don't mind going over a little.*

#1 recommended is the Drolet Tundra

I had also asked about these below?
Englander 3000
US Stove Hot Blast 1400 or 1500
Vogelzang Norsemen 2500

Someone quoted on top of the chimney liner, insulation and furnace - _"there will need to be one or two back draft dampers installed. add maybe $1000 for the additional sheet metal fabrication and installation"
_
Thanks


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## maple1 (Jan 30, 2015)

I only see one question in there, on the Ts - and I don't know the answer, have no experience with liners at all.

But if it was a question further down - I would pick the Tundra over the other 3 you mention, even if the others are a bit cheaper. There was a nice post showing a good Drolet installation in another thread earlier today or yesterday - should be able to find it, it's not down the thread list very far, forget which one it was now. Had good info on dampers too.

EDIT: https://www.hearth.com/talk/threads/hooking-up-a-drolet-tundra.138994/


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## roofyroo (Feb 1, 2015)

Thanks for responding, and no, I didn't really ask a question. I was just looking for input.

The 3 other units I mentioned are $600 less. I'd love to get what everyone is recommending but the total cost for this whole install will add up to too much. The next cost I'm trying to figure out is the additional material.

Here is the chimney flue we'll use and the current forced air furnace next to it.
http://s12.postimg.org/6n6ppcwsd/air.jpg

I checked out the other link for the Drolet install. Our house is old and has no cold air return. Not great I know, but thats the way it is for now. With that in mind would all I need to do is hook the double vents into the plenum with back draft dampers, and the exhaust the chimney flue? I don't believe there is anything else?


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## brenndatomu (Feb 1, 2015)

roofyroo said:


> The 3 other units I mentioned are $600 less.


And all but the Englander are _actually worth_ $1200 less, and that's being generous. Hot Blast and Norseman are chimney plugging wood hogs. 
Hopefully you didn't just miss seeing the $1250 sale Menards was having last week on the Tundra, still on sale for $1400, which is still a really good price. You'd have another ~$300 or so in shipping since there are no Menards around you.
You can probably tie in using prefab round duct work and DIY, save a TON of $. Should be _way less_ than $1k.
Shop around on the chimney liner, Rockford, Chimney Liner Depot, Woodland Direct, there are many others. Don't over think a liner, they all hafta meet the same regs. No sense spendin big $ on "gingerbread" IMO. Get a SS liner made for wood burning, insulation kit from the same company, tee kit, top cap, git 'er dun. Heck, I'd say a chimney liner kit and your duct work shouldn't be much more than $1k all total.
You'll need an additional thermostat ('cept the Englander), like a FocusPro 5000 works good for wood burning furnaces. Can be bought $20 or less on fleabay if you shop a bit. Half dozen on there right now less than $15 delivered.
Sounds like you have a pretty handle on the basics of what you'd need.


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## roofyroo (Feb 1, 2015)

If I'm looking at the Tundra for say $1800, then are you saying these 2 units (US Stove Hot Blast 1500 OR Vogelzang Norsemen 2500) are worth about $1200 less - i.e. they aren't worth much at all? Anyone else have an opinion on this? Just because I see good reviews about all of them.

*All* the chimney liner kits state that is burning wood then they should be insulated. I want to make sure that what I'm putting in is safe, so buying the 30' liner for my 27' chimney, and then buying the 25' insulation should be enough? I don't need to insulate the top 2', or do I need to buy 2' more?

I haven't looked at round duct work yet but should I assume that I buy roughly the right size including the bends (elbows or whatever you call them) and then cut into the havoc with steel cutters and then seal with foil tape?

Looking at my basement photo I was going to place the furnace to the left of the current furnace?


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## brenndatomu (Feb 1, 2015)

roofyroo said:


> I see good reviews about all of them.


Use the search feature on here and over on AS, there aren't too many people that like them after they have them a while. Most hate 'em. Do a CL search there are a TON of these kind of wood furnaces for sale. I know the Tundra hasn't been around as long but I haven't seen a used one for sale yet. Quite a few owners here and on AS, pretty well liked. I can only recall 1 guy that didn't like his Tundra, but he had the first model year problems and I personally think he had caused some of his own too. Very little to no customer service with the other two models, but Drolet is well thought of in that regard. Any other real issues have been initial setup problems or operator learning curve. Heck, I just ordered one for my sister to replace her wood hog smoke dragon.



roofyroo said:


> I don't need to insulate the top 2', or do I need to buy 2' more?


The top needs the insulation the most, the flue gasses are the coolest there and the chimney is completely exposed there too. So you have a full 27' from breech to chimney cap? It shouldn't be much more for a few extra feet of insulation. The last liner I bought they threw in some extra "scrap" pieces for free. It actually ended up being quite a bit of material.



roofyroo said:


> I haven't looked at round duct work yet but should I assume that I buy roughly the right size including the bends (elbows or whatever you call them) and then cut into the havoc with steel cutters and then seal with foil tape?


Yep, more or less



roofyroo said:


> Looking at my basement photo I was going to place the furnace to the left of the current furnace?


That should work as long as minimum CTC (recommended minimum clearance to combustibles) is met


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## maple1 (Feb 1, 2015)

This is one time I would not go for the cheapest thing - I would buy the Tundra over the rest of those, no doubt. You will be stuck living with whatever you get, long after the initial purchase cost - well worth the extra cost in this case, I would say. Granted that's without having no direct experience with any of them, but some trends develop & come through loud & clear if you do enough reading from people that do have the experience. I can indirectly relate though after living for 17 years with an inefficient boiler, and into 3 now with a good one - best $15k I ever spent, even if I haven't fully recovered from that hit yet.


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## Buzz Saw (Feb 1, 2015)

I've got a hot blast....for now.  It gets the job done but eats wood.  I only bought it b/c it was cheap on CL. I wouldn't do it if I was stsying in this house for the long haul.The Hot blast is staying with the house when it sells this Spring. I'll be upgrading to something else, can't wait!


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## roofyroo (Feb 15, 2015)

I went with all this in the end and installed it myself. Actually pretty easy after spending time to research and understand the system - and some advice form people on here.

Drolet Tundra (from Menards $1400 + $300 shipping to VA)
Z-flex 30ft chimney liner kit + 30ft liner insulation because I'm burning wood - $950
High temperature black duct for the chimney exhaust and standard silver duct for the 2 connections to the HVAC, few packs of self drilling screws, foil tape, high temp caulk ~ $150

Need to do some additional work covering the chimney and also hook in the two hot air outlets into the HVAC.

*Do I really need to install back draft dampers on the duct into the HVAC?*


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## STIHLY DAN (Feb 15, 2015)

No BDR?


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## brenndatomu (Feb 15, 2015)

roofyroo said:


> Do I really need to install back draft dampers on the duct into the HVAC?


Chances are, yes. Try it and see if the gas(?) furnace plenum gets warm below where you tie in, if it does then you need a damper. 



STIHLY DAN said:


> No BDR?


As dan says, with a chimney that high, you _WILL_ need a flue damper, a manual key damper, or a BDR, maybe both


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## maple1 (Feb 15, 2015)

brenndatomu said:


> Chances are, yes. Try it and see if the gas(?) furnace plenum gets warm below where you tie in, if it does then you need a damper.
> 
> 
> As dan says, with a chimney that high, you _WILL_ need a flue damper, a manual key damper, or a BDR, maybe both



Then you get to the point of adjusting them for proper draft. Dwyer MarkII Model 25 highly recommended for any furnace owner.


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## STIHLY DAN (Feb 15, 2015)

roofyroo said:


> Do I really need to install back draft dampers on the duct into the HVAC?



If you are going to use wood heat only you can just tape a piece of cardboard to your filter grill.


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## roofyroo (Feb 15, 2015)

The Tundra manual says not to attach a damper to the exhaust.

The plenum get warm below the tie in points. If I turn on the fan on our HVAC then the tie in ports cool down as the Tundra blower will not kick in. I need to hook in the 2 back draft dampers when they arrive and see if that helps.

We have an old house, so a lot of duct that maybe isn't laid out as efficient as it should be. I've changed the Tundra fan to max to blow as much air through as possible - but not doing too great yet.

Should I try and have our HVAC fan on as well, as long as the back draft dampers are installed?

Thanks


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## brenndatomu (Feb 15, 2015)

roofyroo said:


> The Tundra manual says not to attach a damper to the exhaust.


The TUNDRA furnace must be connected to a factory built chimney as per UL 103 HT or
ULC S629 for wood heating appliances, we recommend that the connecting pipe and
chimney have a 6" inside diameter. The minimum draft required at all times is -0.04 in.
W.C. but the furnace will perform at its best with a draft of -0.06 in. W.C.
Slightly higher draft is acceptable and a barometric draft control is not normally required on
this unit but a barometric control must be installed to control excessive draft (more than -
0.08 in. W.C.).

This is from section 6.3 of the manual, notice the last line, draft _must_ be controlled (if excessive, and a 27' chimney will be excessive, mine is). They recommend a BDR which is fine, but my experience, and I think others here would agree, is that they cool the flue too much and can cause some creosote issues. If you are gonna pull the pipe apart to install a damper, then I'd go ahead and put both in, key dampers are cheap.
Did you slide the cardboard in the filter housing to act as a temporary backdraft damper as Dan suggested?
The fan on the Tundra is rated at 1400CFM so it should be adequate for a house the size of yours. If you run both furnace fans they will be fighting each other and also the air from the gas furnace will cool the air steam from the Tundra.


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## roofyroo (Feb 15, 2015)

Let me get this right as I believe I'm missing somethings and some steps...

1. I should install a 6" barometric damper somewhere on the exhaust line from the furnace to the chimney?
2. Buy a manometer to measure the air pressure in the exhaust line. Any suggestions as to something inexpensive? I see they range a lot on price.
3. Install a back draft damper on each hot air outlet.
4. Measure the static air pressure in the hot air outlets.


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## brenndatomu (Feb 15, 2015)

maple1 said:


> Then you get to the point of adjusting them for proper draft. Dwyer MarkII Model 25 highly recommended for any furnace owner.


+1 on the Dwyer manometer. Can be had for $20 or so on fleabay if you shop a bit or usually $30 will get you one now.


roofyroo said:


> Let me get this right as I believe I'm missing somethings and some steps...
> 
> 1. I should install a 6" barometric damper somewhere on the exhaust line from the furnace to the chimney?
> 2. Buy a manometer to measure the air pressure in the exhaust line. Any suggestions as to something inexpensive? I see they range a lot on price.
> ...


1. Yes, and/or a manual damper
2. See above
3. Yes, and one in the gas furnace too
4. Yes but that is probably not too important if you do the other things first and it is doing the job for you


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## roofyroo (Feb 16, 2015)

Here's what we have right now.






So you're saying the existing furnace (square unit in the middle) also needs a back draft damper? *This should be installed...where?*

I picked up a barometric damper today to install on the exhaust to the chimney flue. No where around here carries back draft dampers for the hot air outlets unless it's ordered in.


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## laynes69 (Feb 16, 2015)

A backdraft damper should be installed directly above the central furnace, before your two ducts. This helps to keep the woodfurnace from backfeeding. While the wood furnace is running, can you feel heat exiting the central furnace at the base? If so, you won't get the flow into the main ductwork. Blocking the base of the central furnace would allow pressure to build in your ductwork and flow into your home. If you block it, do not operate the central furnace. Installing the barometric damper and setting it for the highest draft should be safe. Even if it's at .08" you'll be okay. Once the damper closes and the flue temps drop, so will the draft.


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## roofyroo (Feb 16, 2015)

Right okay I understand now when Dan said...



STIHLY DAN said:


> If you are going to use wood heat only you can just tape a piece of cardboard to your filter grill.



I originally thought he meant the filter on my Tundra. That makes more sense as the heat was venting from the base of the main furnace - hence why the house was getting marginally warmer but nothing like I was expecting.

Also I assume if I get one BIG back draft damper for the main furnace then I won't need the 2 8" back draft dampers for the hot air outlets from the wood furnace?


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## laynes69 (Feb 16, 2015)

I would still have the two 8" dampers. If you choose not to use the woodfurnace and want to run the central furnace, then close them. Ideally  for the main backdraft damper, you just want something that will open when the central furnace blower runs, and close when off.


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## roofyroo (Feb 16, 2015)

So the main backdraft damper in the top of the electric furnace would still be big though - like to fit the whole square inside?

Thanks by the way - card is helping already. Can't get the house above 66 right now though :/


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## DoubleB (Feb 16, 2015)

It appears you could alternatively prevent backflow into the electric furnace by using two backdraft dampers--both in the rectangular trunk above your electric furnace, one damper each between each 8" pipe and the electric furnace.  You might consider this if it's easier to get at the main trunk than adding a single backdraft damper top of the electric furnace.  A potential problem, though, is that the left 8" duct would only serve registers on the left, and the right 8" duct would only serve registers on the right.  And if you have a significantly different amount of registers on either end, you would get imbalanced flow.

Not to mention if you have any runs coming off the trunk right above the furnace, they wouldn't get any warm air from the Tundra.


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## roofyroo (Feb 16, 2015)

I thought about installing 2 but you're right, the airflow would be very imbalanced. Not sure how to install one large backdraft damper yet in the main trunk of the electric furnace, but thats the way to go.

So far the cardboard in the filter is working, although not ideal!


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## laynes69 (Feb 16, 2015)

All of our ductwork comes off the woodfurnace and not the central furnace. Because of this, I needed a way to prevent backfeeding. I ended up building a backdraft damper that butterflies open in the middle. That way, I didn't have a large damper swinging open, due to no room. It works well.


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## brenndatomu (Feb 16, 2015)

You can make a damper by screwing some angle around the inside of the furnace plenum. Then clamp a pivot rod to 1 or 2 (as laynes said) pieces of sheet metal, install on top of the angles. Furnace blower will blow it open but block the flow from the Tundra


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## roofyroo (Feb 17, 2015)

My main concern is everything being safe so small steps and suggestions have been great so far.

I've gone to the effort of laying out a schematic of our duct and vents. The house is old so there is no return apart from a vent in the stair wall leading down to the basement.





The addition that was built at some point is _*COLD! *_I managed to check under the floor and there is no insulation - it's just built off the ground. I'm sure at some point insulation will do some wonders there.

I don't think I am burning the furnace hot enough. I just added more wood and opened the air inlet damper and came upstairs with intention of heading back down in 5 minutes. I forgot and ended up going down to close the damper after about 15-20 minutes and the furnace is now raging and the hot air outlets are pretty warm. The house temp has gone up as well.
*So in people's experience it's okay to leave the inlet damper open for that period of time?* If I don't then it seems it isn't kicking out enough heat. This is all new to me so maybe this is normal.


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## roofyroo (Feb 17, 2015)

Currently there is no:

barometric damper installed on the chimney exhaust line
8" backdraft dampers on either hot air outlet from the wood furnace
backdraft damper in the electric furnace
The electric furnace has a large sheet of cardboard covering the filter at the base to block hot air escaping to the basement.


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## laynes69 (Feb 17, 2015)

I run our furnace between 10-20 minutes before shutting it down. If it doesn't get up to temperature, it won't produce much heat.


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## joes169 (Feb 17, 2015)

roofyroo said:


> *So in people's experience it's okay to leave the inlet damper open for that period of time?* If I don't then it seems it isn't kicking out enough heat. This is all new to me so maybe this is normal.



I've got a Caddy, which shares the same firebox design, but the damper door is controlled by the thermostat.  When it gets down around zero degrees, it's not uncommon for the damper door to be open for 4-6 hours if it's not attended to overnight, etc...  I'm not sure there's any reason you would have trouble leaving it open foran hour or two, unless  the units are that vastly different?

On a side unit, I', pretty sure your duct work isn't up to snuff, as I believe the first 6' needs a minimum of 6" clearance to combustables (floor joists and wood beam in this case).........


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## roofyroo (Feb 17, 2015)

Great thanks for your response!

I'm beginning to think that burning the furnace hot for a longer period would be fine. I was paranoid to begin with as this is new to me and obviously I don't want to burn the house down.

The thermostat is on my list so the control will be somewhat automatic.

Duct work is more than 6" away from anything as it's running the top third of the basement until it branches off, then it's near the ceiling.

*Any tips on adding wood? Should I try and burn each load down before adding another load, or just keep adding here and there as needed? Big pieces in the middle or side or bury them down to the bottom of the coals etc?*


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## roofyroo (Feb 17, 2015)

Will burning with the damper inlet open use significantly more wood meaning the heat won't last all night because the furnace will need re-filling?


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## laynes69 (Feb 17, 2015)

roofyroo said:


> Will burning with the damper inlet open use significantly more wood meaning the heat won't last all night because the furnace will need re-filling?



I wouldn't burn wide open with an unregulated draft. Especially on a full fresh load. After a while, burning with the damper open is okay. Even during peak demands, the damper shouldn't remain open for a long period of time. For sure, get a thermostat on the furnace. Even if it remains open for a long period, we still have coals and a warm home.


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## roofyroo (Feb 17, 2015)

Any advice on a thermostat? I assume it doesn't need to be an expensive one for this purpose?


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## laynes69 (Feb 17, 2015)

No, I used a cheap digital thermostat for our furnace. I think I paid $20.


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## DoubleB (Feb 17, 2015)

roofyroo said:


> Any advice on a thermostat? I assume it doesn't need to be an expensive one for this purpose?



That's how I see it.  Simpler is better here, since it's impractical to try to program a thermostat for a wood furnace.  

If I have moist wood, or more commonly if I have small wood (that offgasses quickly), I'll burn with the damper wide open for even 60 minutes to burn off all the smoke, but just do a small size load to prevent it from overheating.  Technically, there is an overtemp cutout that will shut the damper if hot air temp hits 160 degrees.  I've never had that happen to me (that I know of).  

In fact, even with a thermostat, it will run the damper wide open if temp is too low, without you even knowing, so I'm assuming the Tundra can take a good bit of heat.

Of course, I have some paint flaking off the front of my Tundra, presumably due to heat...


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## DoubleB (Feb 17, 2015)

Also, if you are finding the temporary cardboard "damper" to be effective, you might consider putting the backdraft damper on the electric furnace air inlet.  So cold air can come in to the electric furnace but not back out.  Very accessible and lots of room to put in on.  Effect is the same as putting it on top of the electric furnace. 

However, .  If there are enough air leaks, you'll get some hot air backfeeding through your electric furnace.  I'm not smart enough to know if that is a problem.  But I've heard people say that wood furnace hot air gets hot enough to mess up air conditioning coils, which I see that you have.


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## brenndatomu (Feb 17, 2015)

roofyroo said:


> Will burning with the damper inlet open use significantly more wood meaning the heat won't last all night because the furnace will need re-filling?


Yes


laynes69 said:


> I wouldn't burn wide open with an unregulated draft.


+1 ^ ^ ^


roofyroo said:


> Any advice on a thermostat?


Honeywell FocusPro 5000, works good with a wood furnace, can be had for $20 or less on fleabay...


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## joes169 (Feb 17, 2015)

laynes69 said:


> I wouldn't burn wide open with an unregulated draft. Especially on a full fresh load. After a while, burning with the damper open is okay. Even during peak demands, the damper shouldn't remain open for a long period of time. For sure, get a thermostat on the furnace. Even if it remains open for a long period, we still have coals and a warm home.




Maybe the Tundra operates completely different than the Caddy, but do you see periods, when you need to "catch up" a few degrees after getting behind, that your damper door stays open for a few hours??


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## STIHLY DAN (Feb 17, 2015)

I;m sorry but you really should finish the install before figuring out how to use it. Doe's this unit come with an install manual? It is specifically made for easy homeowner installation. This is like saying the car isn't running right but the wheels aren't on yet, I need an injector, and I have old gas. Why am I not going anywhere fast.


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## laynes69 (Feb 17, 2015)

It operates exactly the same, same servo, same damper. To be honest, our furnace doesn't get behind often. The only time we dropped below our setpoint at 72 overnight was recently with a nighttime low of -10°F with windchills aproaching 40 below. It was 68°F in the home when I woke and the furnace consumed a full firebox in 7 hours which I thought was very good. Instead of pushing the woodfurnace when I woke, I ran the LP for 1 cycle, about 10 minutes to bring the home at 71° then shut off the LP and the woodfurnace then maintained the home. We are looking at -14°F Thursday night and it may be the same scenario. This morning, it was -6° and 70 when I woke up from overnight. Within 15 minutes of loading the furnace, the temperature raised 1 degree and I closed the damper. From there it climbed and maintained 72 for when my wife got up. If it's that cold and there's a very heavy demand for heat, I won't keep it open the entire time. It wastes wood and pushes heat out the flue. Instead, let it get very hot where it starts to climb and close the damper. It should continue to produce alot of heat, while preserving wood. Once it gets close to the coaling stage and it's that cold, the damper pretty much remains open. The major difference between the two furnaces ( Caddy and Tundra) is the jacket. We have a large plenum opening which allows for excellent airflow thru our ductwork.


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## joes169 (Feb 17, 2015)

laynes69 said:


> It operates exactly the same, same servo, same damper. To be honest, our furnace doesn't get behind often. The only time we dropped below our setpoint at 72 overnight was recently with a nighttime low of -10°F with windchills aproaching 40 below. It was 68°F in the home when I woke and the furnace consumed a full firebox in 7 hours which I thought was very good. Instead of pushing the woodfurnace when I woke, I ran the LP for 1 cycle, about 10 minutes to bring the home at 71° then shut off the LP and the woodfurnace then maintained the home. We are looking at -14°F Thursday night and it may be the same scenario. This morning, it was -6° and 70 when I woke up from overnight. Within 15 minutes of loading the furnace, the temperature raised 1 degree and I closed the damper. From there it climbed and maintained 72 for when my wife got up. If it's that cold and there's a very heavy demand for heat, I won't keep it open the entire time. It wastes wood and pushes heat out the flue. Instead, let it get very hot where it starts to climb and close the damper. It should continue to produce alot of heat, while preserving wood. Once it gets close to the coaling stage and it's that cold, the damper pretty much remains open. The major difference between the two furnaces ( Caddy and Tundra) is the jacket. We have a large plenum opening which allows for excellent airflow thru our ductwork.




Thank you for the great response.  I don't want to infringe too much on the original poster, so I'll likely just start a separate thread of my my own set-up when I get a chance to upload some pictures.  I have a few ideas on why I maybe seeing lackluster performance from my Caddy, but I'll look for some additional assistance in the near future here............


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## martae (Feb 17, 2015)

The complexity of this "flue project" has sold me on outdoor wood boilers.  Is there one that is a true downdraft wood gasification boiler?  Or maybe a "basement" boiler in a small boiler house that would double as a wood shed.  I like the idea of a straight, vertical six or eight foot flue, passing through nothing but a metal roof, and some fiberglass insulation.


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## maple1 (Feb 18, 2015)

martae said:


> The complexity of this "flue project" has sold me on outdoor wood boilers.  Is there one that is a true downdraft wood gasification boiler?  Or maybe a "basement" boiler in a small boiler house that would double as a wood shed.  I like the idea of a straight, vertical six or eight foot flue, passing through nothing but a metal roof, and some fiberglass insulation.


 
That's not quite on the thread topic - but I'd say that's not reason enough to go OWB. Doing a flue is a one-time thing, keeping an OWB in wood is a lifetime-of-the-boiler thing.


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## brenndatomu (Feb 18, 2015)

martae said:


> The complexity of this "flue project" has sold me on outdoor wood boilers.


flue project?


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## roofyroo (Feb 18, 2015)

DoubleB said:


> Also, if you are finding the temporary cardboard "damper" to be effective, you might consider putting the backdraft damper on the electric furnace air inlet. So cold air can come in to the electric furnace but not back out. Very accessible and lots of room to put in on. Effect is the same as putting it on top of the electric furnace.
> However, . If there are enough air leaks, you'll get some hot air backfeeding through your electric furnace. I'm not smart enough to know if that is a problem. But I've heard people say that wood furnace hot air gets hot enough to mess up air conditioning coils, which I see that you have.



I wanted to quote all the above so it makes sense to anyone else, but specifically wondering about the last comment to do with hot air messing up the air conditioning coils. *Any other input on this?* I love the idea of putting a backdraft damper where the filter is as it would make  my life SO much easier!


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## brenndatomu (Feb 18, 2015)

Since the coil is not in the plenum right on top the Tundra, I think it will be fine, temp has dropped a bit by the time it gets over there. The plastic drip tray that I mentioned before, now that I think about it, will probably be OK too. Just FYI, Yukon says that the AC coils are fine being mounted over their furnaces, and they are certified to run during power outage, so we are talking serious heat buildup there! No plastic drip pans on a Yukon! If you have the room to do backdraft damper in filter housing area I would think it would work fine


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## roofyroo (Feb 18, 2015)

Thanks for your input!


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## DoubleB (Feb 18, 2015)

I think Brenndatomu's assessment sounds pretty realistic.  I didn't mean to cause alarm with the ac coil, but something to pay attention to since I don't know much about the risks.

I try to cover my bases on these kinds of things...if I was in your shoes it's pretty easy to stick a thermometer in the a/c coil and see what you get (with the cardboard installed).  Could even pull the plug on the Tundra and measure temps then too without a blower.  Assuming you measure reasonable temps on the coil, then I'd do the backdraft damper on the electric furnace cold air intake for the simplicity and access.


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## Smoke Signals (Feb 18, 2015)

DoubleB said:


> Also, if you are finding the temporary cardboard "damper" to be effective, you might consider putting the backdraft damper on the electric furnace air *inlet.*



+1


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## TheBigIron (Feb 18, 2015)

Good evening all.

I have a question about insulating a ss chimney liner.  Since my chimney is located in the middle of my home and is heated with the homes heat except the last 15ft or so I was wondering if I need to insulate the whole length of the chimney?  Approximately 30' or so.  I'm installing a Drolet Tundra in my basement.  Thanks for your input.

Dave..


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## roofyroo (Feb 21, 2015)

Copying 2 previous images  as I'm considering changing the duct work.

Is there any reason why the 2 hot air outlets from the Tundra cannot go into the bottom of the electric furnace (filter area)? That way I can utilize both fans and it will avoid the whole blocking up the filter at the base with cardboard to avoid losing heat from the Tundra. If so then would it go in through the side?


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## brenndatomu (Feb 21, 2015)

Well, a couple reason why that's not a good idea...
1. The duct work will have to go down from the tundra meaning if there is a power outage you have ton of trapped hot (and getting hotter) air in the ducts...tundra not getting any cooling...need I go on?
2. The blower motor of the furnace is made to take in cool air, hot air will shorten the motor life greatly...
It could be done buts it's really not a good idea


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## roofyroo (Feb 21, 2015)

Okay that makes sense - worth asking.

What about this type of scenario?


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## brenndatomu (Feb 21, 2015)

If I understand the drawing right then that should be fine


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## roofyroo (Feb 21, 2015)

Do people think that would be the most efficient? Before I really go to town setting it all up I'm trying to get the install as efficient as possible for what I have to deal with in my basement.

Currently (from the photo) you can see the 2 hot air outlets going off to each side of the main duct which is also tied into the top of our existing electric furnace (and ac).


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## DoubleB (Feb 21, 2015)

You don't want to put the backdraft damper on your electric furnace inlet?  That seemed like the least invasive of your options.  That's equivalent to your drawing above, so to answer your question, that's what I vote would be the most efficient first solution.


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## brenndatomu (Feb 21, 2015)

After thinking more about your earlier idea of putting the damper down in the filter housing, I think it is better being above the furnace somewhere. Reason being is that blowers don't do too well with much if any restriction on the low pressure side (filter, or "vacuum" side) and pulling the damper open would cause some restriction. So I like your current plan the best


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## DoubleB (Feb 21, 2015)

brenndatomu said:


> blowers don't do too well with much if any restriction on the low pressure side



Hard to argue with that.  I had wondered that too, but convinced myself that I was getting confused with a check valve before a water pump, where cavitation is a concern.  If you say it's a concern with blowers, then I believe you.


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## roofyroo (Feb 21, 2015)

Thanks guys 

I had suggestions about putting the hot air outlets into the filter area of the electric furnace because the electric furnace blower is the strongest and would push the hot air around my duct more than just the blowers from the wood furnace. That made sense to me too, except worrying over the long term effects to the electric furnace/ac.

So I like the idea of the sketch above.


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## brenndatomu (Feb 21, 2015)

DoubleB said:


> Hard to argue with that.  I had wondered that too, but convinced myself that I was getting confused with a check valve before a water pump, where cavitation is a concern.  If you say it's a concern with blowers, then I believe you.


Water pump or air pump, many of the same principals apply


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## Smoke Signals (Feb 21, 2015)

brenndatomu said:


> After thinking more about your earlier idea of putting the damper down in the filter housing, I think it is better being above the furnace somewhere. Reason being is that blowers don't do too well with much if any restriction on the low pressure side (filter, or "vacuum" side) and pulling the damper open would cause some restriction. So I like your current plan the best



Agreed. I think what you have sketched out above is a better way to go but I would still test the theory by blocking off the filter in the electric furnace so you can see if it's going to cure you woes. That way you will know if you need to make other mods before you rework your duct work and can get it all done in one shot.


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## Smoke Signals (Feb 21, 2015)

One other thought, if you plan to use the wood furnace for your primary heat source you may want to consider using manual dampers in the two 8" pipes coming from the Tundra. In case of a power failure the heat from the wood burner may not be able to push the back draft dampers open so it would be best if they just stay open. Then you would just close the manual dampers if you need to run the electric back up.


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## brenndatomu (Feb 21, 2015)

Smoke Signals said:


> One other thought, if you plan to use the wood furnace for your primary heat source you may want to consider using manual dampers in the two 8" pipes coming from the Tundra. In case of a power failure the heat from the wood burner may not be able to push the back draft dampers open so it would be best if they just stay open. Then you would just close the manual dampers if you need to run the electric back up.


Or another suggestion I have seen in the past is to install powered close/spring open dampers, that way if power is lost it can still gravity flow


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## roofyroo (Feb 21, 2015)

I have two 8" backdraft dampers coming this week so will see what difference this makes.

On the subject of dampers, I've read here that some people are using a manual damper on the exhaust, which contradicts page 36 of the manual which states "WARNING: DO NOT INSTALL A MANUAL DAMPER ON THIS FURNACE" (bold text, underlined and boxed). I understand the damper is installed to keep the hot air in the furnace, but it seems an extreme choice for such an extreme warning from Drolet.
I'm mentioning this as my exhaust is VERY hot, so I'm worried about the amount of heat I'm losing. I have a barometric damper to install along with a manometer and in-flue rod. I'm concerned that with this extreme heat, hot air will escape out of the T where the barometric damper is. Do you guys have a barometric damper installed, or a manual damper, or nothing at all on the exhaust?


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## joes169 (Feb 21, 2015)

I have a barometric, and can tell you it's nearly impossible for these flues to leak hot air into the house.  Keep in mind what's happening in the chimney: there's a strong draw, or negative pressure (or at least there better be).  Any non-sealed portions of the flue will leak cold room air into the flue before they'll allow any out......


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## roofyroo (Feb 22, 2015)

Great - that makes me feel much better - thanks!


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## brenndatomu (Feb 22, 2015)

I like options so I personally have both a manual and barometric damper on my stove pipe. I have had creosote issues with my baro, but I also am not running a Tundra, so take that for what it's worth. I normally control the draft with the manual (or key) damper leaving the baro opening covered with HD alum foil. But I use the baro on real windy days where the draft is really erratic or really cold/windy days where neither damper is enough to get the draft reading down to normal operating levels. (I have a 28' high draft chimney) Also the baro is used when I use the oil burner. I am planning on putting both types of dampers on my sisters Tundra when I install it too.

I would say that Drolet emphasizes the use of a baro to satisfy the lawyers, it adds one more layer of "idiot proof" to running the furnace, and this furnace is marketed toward the masses, so...
I personally would put a lot more emphasis on their statement that the draft must be controlled to the range of -.04" WC to -.08" WC, maybe not as much on how it's controlled.

If your stove pipe is that hot (I can't remember, did you ever give us flue temps?) then you definitely are losing heat up the flue and are in need of a damper...adjusted properly using a manometer.

As joe said, the chimney and flue provide negative pressure to the firebox so there should never be any smoke coming out. There is normally a little air being drawn into every pipe joint and about the only way I can think of that smoke will come out is if you get "backpuffing" or have a plugged chimney. If you do have smoke coming out the joints it is nearly impossible to seal everything to the point of not getting smoke in the house, but like I said, when everything is right, the chimney provides "suction" that only pulls air in, but lets none out.
And that brings up a point,  the chimney is the "engine" that powers the stove/furnace so to speak. The stove/furnace is kinda like a car, without an engine it is just a body, and the car can only work as good as it's engine is "tuned", that's why it is so important to get the draft set correctly.


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## TheBigIron (Feb 22, 2015)

roofyroo said:


> I have two 8" backdraft dampers coming this week so will see what difference this makes.
> 
> On the subject of dampers, I've read here that some people are using a manual damper on the exhaust, which contradicts page 36 of the manual which states "WARNING: DO NOT INSTALL A MANUAL DAMPER ON THIS FURNACE" (bold text, underlined and boxed). I understand the damper is installed to keep the hot air in the furnace, but it seems an extreme choice for such an extreme warning from Drolet.
> I'm mentioning this as my exhaust is VERY hot, so I'm worried about the amount of heat I'm losing. I have a barometric damper to install along with a manometer and in-flue rod. I'm concerned that with this extreme heat, hot air will escape out of the T where the barometric damper is. Do you guys have a barometric damper installed, or a manual damper, or nothing at all on the exhaust?


Roofyroo,

What kind of 8" dampers are you using for the outlets on the Tundra?  And are you using any backdraft damper on the return side of the Tundra?

Thanks Dave


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## roofyroo (Feb 22, 2015)

I'm waiting for the dampers to turn up this week for the outlets on the Tundra - backdraft dampers.

There is no air return in our house as it's old, so just the optional filter intake on the Tundra.

Hope that makes sense...


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## JRHAWK9 (Feb 22, 2015)

With all gravity backdraft dampers, how will you account for proper firebox heat dissipation in the event of a power outage?  You will not have gravity flow....?

I have a gravity damper in the bonnet of the LP furnace and a powered damper in the supply duct of the wood furnace.  It's wired in such a way utilizing a relay where the ONLY time it's closed is when fan on the LP furnace/AC is the only one running.  This gives backdraft protection in all scenarios (also allows for both the LP and wood blowers to run at the same time) and also allows for gravity flow in case of a power outage.


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## TheBigIron (Feb 23, 2015)

JRHAWK9

Where did you order your motorized damper from?  Any input would be appreciated

Thanks Dave


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## JRHAWK9 (Feb 23, 2015)

The46Zone said:


> JRHAWK9
> 
> Where did you order your motorized damper from?  Any input would be appreciated
> 
> Thanks Dave



I got it from Retrozone (Google them).  They were very helpful as well.  I went with one of their better models and also got the Belimo motor.


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## TheBigIron (Feb 23, 2015)

JRHAWK9 said:


> I got it from Retrozone (Google them).  They were very helpful as well.  I went with one of their better models and also got the Belimo motor.


 Thanks for the input.  Dave


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## roofyroo (Mar 2, 2015)

I've been watching my 2 threads and gathering info from all the wonderfully useful input 

After talking to a few specialist companies in the area and ductwork bending companies I'm going to change my hookup to be like this.






I've been looking around at 18x12 motorized dampers and wondered about people's opinions. I have checked out the ones from Retrozone as per 





JRHAWK9 said:


> I got it from Retrozone


.

Are there other components I need to hookup a motorized damper? Some say they need a relay switch and some say they do not need one.


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## DoubleB (Mar 2, 2015)

I don't recall all of the discussion, but I think someone pointed out you might have trouble in a power outage.  Tundra keeps making heat, but there's nowhere for it to float away in the above picture.  

Also, the series installation may be trouble; look at page 49 of the manual, you'll see a similar picture (wood furnace and LP furnace are reversed), with a big X through it saying it's not approved.  

Your house, your decision, just thought I'd bring it up, I know it's easy to forget all the things to keep in mind.


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## Smoke Signals (Mar 2, 2015)

If you are stuck on running them in series perhaps you could put a normal open damper between the tundra supply and the main duct and tie it into line power so it would only open when the power fails for a heat dump.


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## roofyroo (Mar 3, 2015)

I was thinking about the manual and installing in parallel. Page 49 Diagram 7.5.3 clearly shows the "other" furnace feeding into the Tundra as not permitted, not the other way around. We're not planning on running both at the same time.

I'm struggling with understanding the exact "how" the back draft damper will work. Does it tie into the thermostat of the electric furnace? Do I need to buy a control box?


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## brenndatomu (Mar 3, 2015)

The issue with tying in to the cold air side of the main furnace is that all the hot air is trapped in the event of a power loss...Tundra overheats.
If you want to do it this way then You need a emergency heat dump door like Yukon sells   (http://www.yukon-eagle.com/FURNACEACCESSORIES/SAFETYHEATDUMP/tabid/200/Default.aspx)   which will mean that you will have to install a plenum on the Tundra, or I suppose you could put a large "power closed/spring open" damper on the Tundra plenum to dump heat to the basement during power failure.
I would think you will need a 24vac controlled relay to control the damper. 24v side to the main furnace thermostat, 120v side to the damper. Unless the dampers run on 24v...then maybe it could just be wired direct to the 'stat. Or maybe some dampers have relays built in, I dunno. Maybe someone more familiar with powered dampers will chime in


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## DoubleB (Mar 3, 2015)

roofyroo said:


> Page 49 Diagram 7.5.3 clearly shows the "other" furnace feeding into the Tundra as not permitted, not the other way around. We're not planning on running both at the same time.



Well my point is that a series installation has risks, regardless of which furnace comes first.  I would bet SBI would be even more adverse to the liability of their product dumping hot air into the other furnace than their aversion shown in 7.5.3.

Risks such as overheating components in your electric furnace; your in-laws watch your house and run both furnaces; the next owners of your house run both and sue you after it burns down; etc.  I admit I don't know that any of this will happen and I certainly hope it doesn't.  I'm just fairly conservative about risks that can easily be avoided upfront.  Your house and decision; not mine to judge.


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## Smoke Signals (Mar 3, 2015)

DoubleB said:


> Well my point is that a series installation has risks, regardless of which furnace comes first.  I would bet SBI would be even more adverse to the liability of their product dumping hot air into the other furnace than their aversion shown in 7.5.3.
> 
> Risks such as overheating components in your electric furnace; your in-laws watch your house and run both furnaces; the next owners of your house run both and sue you after it burns down; etc.  I admit I don't know that any of this will happen and I certainly hope it doesn't.  I'm just fairly conservative about risks that can easily be avoided upfront.  Your house and decision; not mine to judge.



I agree with* DoubleB* and* brenndatomu*, I would not run them in series unless I cleared it with SBI first, get there recommendations and be sure to include some kind of heat dump if they ok the setup.

edit: Hey look, my 100th post! not a new member any more.


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## laynes69 (Mar 3, 2015)

If the furnace was meant for series, it would clearly be listed in the manual. I have not seen a single wood furnace that allowed a series install with a restriction in the top of the jacket (2-8" ducts). The Caddy can be series, but only if the plenum of the woodfurnace leads directly into the main ducting, not the other furnace. In the case of a Caddy, the central furnace would push all the heat in one direction. If a power outage occured, there's a large plenum opening for the heat to escape the jacket. 

Also the same reason almost all furnace manufacturers won't allow for a down flow configuration. The first power outage without proper flow will allow for a heat trap to form along with dangerous temperatures. If a furnace does overheat in an outage, I wouldn't want to suck that superheated air into a location with a blower, a circuit board, etc.


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## DoubleB (Mar 3, 2015)

I'll also remark that I sympathize with your situation.  So many options, each with pros and cons and limitations and requirements.  It can be kind of daunting.  Most of us have been there.  You've already invested a lot of effort and money, you've done lots of good work already that you'll be very satisfied down the road to look at your accomplishments and know that you don't have a weak link that limits the robustness, performance, or safety of your system.

I started planning my install 12 months ago, lots of decisions and work along the way, and I'm still not quite done, but I much prefer knowing I have avoided or addressed known potential problems.  I think others report feeling the same way.


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## DoubleB (Mar 3, 2015)

roofyroo said:


> I'm struggling with understanding the exact "how" the back draft damper will work. Does it tie into the thermostat of the electric furnace? Do I need to buy a control box?



Good question.  You can buy off-the-shelf backdraft dampers, or have one custom made.  Either way, they are passive and mechanical (no control box or connection to a thermostat).  They have one or more flaps that blow open when air blows through the correct direction, but if air tries to blow backwards, the air pushes the flaps closed against a stop.  If you know what a check valve is for fluid, it's the exact same idea.  Your post #54 is the right idea, wherein the backdraft damper on the left would allow the electric furnace to blow air out, but not allow the wood furnace to blow air back into the electric furnace; and wherein the backdraft dampers on the right would allow the Tundra to blow air out, but not allow the electric furnace to blow air back into the Tundra.

Another option, such as Smoke Signals and Brenndatomu described, does involve an electrified damper.  JRHAWK depicts one example quite well in his post #71.  In my opinion, I like his system because in the event of a power outage, a spring in the electrified damper opens it, so that there is no chance that a backdraft damper, even if lightly balanced, would in any way limit the quantity of hot air naturally flowing out of his wood furnace.  Let us (or him) know if you have any questions about that.

Another option, which I took for my house, was just to make a simple duct system for the Tundra that is not connected to the LP furnace.  No backdraft dampers there either.  For what it's worth, the manual says Canada requires a separate duct system.  Evidently the US doesn't, so I'm not arguing, but at least I'm covered if my house moves to Canada.


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## roofyroo (Mar 3, 2015)

Love all the input 


DoubleB said:


> JRHAWK depicts one example quite well in his post #71


This one is difficult as we have extremely low ceilings in our basement, and the plenum that sits on the electric furnace leaves no room to add in any kind of damper.

So maybe back to idea in post #54 - accept I modified (below) because this means the hot air outlets would run straight up into the main duct and also the chimney flue would be very direct rather than the current 2x 90 degree elbows.






To try and figure out the correct, or best, dampers to use could I get opinions on 2 scenarios?

1. What the best setup or dampers are? I presume this involved motorized dampers?

2. What would be a good interim damper setup - as money is now very low on this project (and our household) and it's nearing the end of the cold season (I hope!)? I currently have 2 new 8" backdraft dampers ready to go into the hot air outlets or be returned...

Can I make a manual rectangular damper for the time being? They don't look like much.


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## Smoke Signals (Mar 3, 2015)

IF the tundra will be running most of the time and you will be around if the electric needs to run (like if you were out of wood) I would go with the above set up with the exception of I would use manual dampers in the two 8" pipes coming from the tundra to the main trunk line. Then just close the manual dampers when you need to run the electric furnace.


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## DoubleB (Mar 3, 2015)

roofyroo said:


> What would be a good interim damper setup



If I recall what you're doing now (cardboard in the elec furnace filter?), that is probably fine to limp through the rest of the spring.  Just as long as you don't run the electric furnace without properly restoring it and unplugging the Tundra.  I like to open breakers to make sure someone (like myself) doesn't inadvertently turn something on.



roofyroo said:


> Can I make a manual rectangular damper for the time being? They don't look like much.



If you're handy, as you seem to be, then I'm sure that you can.  If your current setup is temporarily ok, then you can have the spring and summer to make sure the damper is well thought out and fabricated without having to rush.

I have another idea that I'll try to post later if I get some time.


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## JRHAWK9 (Mar 4, 2015)

I have my system dampered and wired in such a way I have full back-flow protection of both furnaces as well as gravity flow from wood furnace in case of power failure.  In addition both furnaces can run at the same time or separately and still be protected from backflow.  I have a gravity damper in the plenum of my LP furnace, a spring-open powered damper in the duct connecting my wood furnace to the main existing duct.  I am using a relay wired like -THIS-.  I'm using the EAC (electronic air cleaner) circuit on the LP furnace for one trigger and the snap disk on the wood furnace as the other one.  Everything works great.  I have my LP furnace set to 65° and have a resettable -MINUTE COUNTER- wired to it to let me know if/how long it runs.  I then log any minutes in a spreadsheet daily along with weight of my daily loadings.


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## roofyroo (Mar 4, 2015)

So manual dampers instead of the backdraft dampers? Maybe both - or is that pointless?


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## JRHAWK9 (Mar 4, 2015)

Personally, I don't like the manual damper idea, it's just asking for trouble if you ever forget to open them when using the wood furnace.  That's the beauty of how I have mine setup.  It's totally fool-proof and completely automatic.  I don't even have to change anything going from heating to cooling season.


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## roofyroo (Mar 4, 2015)

Fully automatic would be awesome - but maybe later in the year once we have more funds.

How about the manual damper inline with the backdraft damper as a "just incase"?


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## Smoke Signals (Mar 4, 2015)

roofyroo said:


> Fully automatic would be awesome - but maybe later in the year once we have more funds.
> 
> How about the manual damper inline with the backdraft damper as a "just incase"?



Please forgive me if you have already answered this but how do you plan to use the Tundra? 1- As your primary heat 2- in conjunction with your electric furnace or 3- as backup to your electric?


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## DoubleB (Mar 4, 2015)

Here is another idea for you, 2 variations of the same.  The advantage that you could put the backdraft dampers in your rectangular duct (instead of above your electric furnace).  The disadvantage that you would have to make two backdraft dampers for your rectangular ducts (instead of just one).

First picture can be set up like JRHAWK did.  Motorized damper can be had from amazon, ebay, even Home Depot for $100.  Second picture uses the backdraft dampers you already purchased over the Tundra, which many others do.

Disclaimer:  I am not a real HVAC guy.


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## roofyroo (Mar 6, 2015)

Thanks for the detailed options above. I'm busy contemplating which is the best way to go before I commit. Also seeing where we are with finances to get this done. I am guessing it'll have to be none motorized dampers initially, then switching them out once funds come in over the Summer.


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