# how necessary is a forced draft on an indoor wood furnace?



## kielbasa (Jan 3, 2009)

Hi guys, I'm still deciding on which indoor add-on wood furnace to purchase (I'm leaning towards a Big Jack or Super Jack)....I noticed most of these furnaces have the forced draft blower motor on them, how often does it actually run? I have zero experience with a furnace that actually has one.
My home is extremely well insulated (thanks ICF!) and temperatures don't fluctuate where the home would be constantly heating up and cooling off....since my furnace will be placed in living quarters, and next to my bedroom (not hidden in the basement or a utility room), the looks without the draft blower are a little more aesthetically pleasing, plus if the fan is noisy I don't want the thing waking me up while trying to get my 5 hours of sleep per night.
I noticed the Energy King has it as an option, and it's quite nice looking (as far as furnaces go), anybody have any experience with an Energy King, and how often the draft blowers operate? Thanks for any input!


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## reaperman (Jan 3, 2009)

My furnace came stock with a draft blower. I'm in my 3rd winter using the furnace and in my case I dont use it at all. If I knew 3 years ago, what I know today, I would never have spent a 1/2 day of fishing a thermostat line from my wood furnace through sheet rocked walls, to a seperate thermostat upstairs.


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## laynes69 (Jan 3, 2009)

The forced draft runs when the thermostat drops to a set temp. Then it ramps up the fire, the air comes from the woodfurnace. When it hits the temp, it shuts off. With a well insulated home, you may not need one. I have one on my furnace, the central furnace is set at 65, the forced draft is set at 68 and the house averages 74-75. So for the most part mine isn't used unless its below zero out. Mine can be noisy, and its in the basement. Nothing to wake me over though.


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## laynes69 (Jan 3, 2009)

reaperman said:


> My furnace came stock with a draft blower. I'm in my 3rd winter using the furnace and in my case I dont use it at all. If I knew 3 years ago, what I know today, I would never have spent a 1/2 day of fishing a thermostat line from my wood furnace through sheet rocked walls, to a seperate thermostat upstairs.




I'm with him.:agree2:


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## kielbasa (Jan 4, 2009)

ok, bear with me, I'm just trying to get a feel as to how these furnaces are to live with....I'll ask a very general, broad question: do you typically load the thing up with wood in the morning, and the furnace automatically regulates its burn depending on thermostat setting? Raging fire to get up to temp and once it's at or near the thermostat setting, the furnace begins to smolder itself out and just idle until the temp falls and the thermostat calls for it again? And then just reload with wood in the evening once the wood has diminished? Is it a repeating cycle like that? Or more of a constant, even burn (probably depends how drafty the home may be)?
Like I said, I've never experienced one of these in action, I've just grownup with freestanding wood stoves my entire life (well, my brother has a Juca furnace, incredible furnace, love the fact that it also throws heat downward and drys my wet boots, gloves, keeps the tile floor warm, etc. AND has radiant heat, so the room that it's in is nice and toasty, but his is not thermostatically controlled)...


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## blakey (Jan 4, 2009)

We used to have a Newmac wood furnace with a draft blower and I would just turn up thermostat when loading wood, then when the fire got going I would turn it back down. The motor eventually wore out and I ran without it just fine. It certainly didn't have the control you are looking for, the blower for the ductwork would run as long as there was heat in the firebox, so the house could get to 80 pretty easy and there was nothing you do besides crack a window and remember to put less wood in next time. 

You are not going to get 12 hr burn times with one of these units, likely 3-4 hrs.
They can't really do the owb trick of shutting the fire right down because of the creosote buildup that would happen. That's my opinion anyway.


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## kielbasa (Jan 4, 2009)

dang salesman! telling me I'd just need to load it up once in the morning and once at night, I should have known better, it does sound too good to be true...
I actually want it 80 degrees inside my house, that's the beauty of wood heat, how hot you want it?! I remeber having a coronary (looking at the $$$ bill) in one of my other houses when I cranked up the natural gas furnace to keep it nice and toasty, never again!


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## MNfarmer (Jan 4, 2009)

kielbasa... which salesman did you talk to?? Did you call the factory about the jack furnaces or was it someone who sells them? I live about4.5 miles from the where the jacks and super jacks are built. Anyway I can help you just let me know!

I just noticed you asked about Energy Kings too. I got a price on them.. I'll have to see if I can find it.. They look like a fairly nice furnace.. way more expensive than one of the Jacks. The thing I didn't like the looks of was the firebrick sits at an angle and tends to get beat up more from the wood compared to firebrick that are straight up and down. If you want the price quote I got for them just let me know.


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## kielbasa (Jan 4, 2009)

I called the factory


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## laynes69 (Jan 4, 2009)

I wouldn't want a whole automatic thing on an indoor wood furnace. Maybe a gassifier, but not a forced air furnace. Where I would worry is it will burn hot, then shut down and smolder. With manual draft, you could load accordingly to the weather and set from there. Having a wood furnace takes some getting used to, but its worth it. Loading twice a day.........yeah right. Gotta love those salesman. For us if its 30 or 40 out, we can load it every 5 hours with 3 small splits. If its below zero, an armfull every 3 to 4 hours. But thats a 70 degree house, with no propane. Weather plays a huge part on wood consumption. If you operated with a forced draft most of the time, expect almost double the wood consumption. Manual is what I prefer, but thats me.


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## merlynr (Jan 4, 2009)

I have a forced draft wood furnace and it is controlled by the wood furnace thermostat which is about two feet from the elec furn/heat pump stat. The forced draft fan has on/off switch on it which is handy when loading wood as u can turn it off to prevent smoking into room. Lots of factors enter into controlling amount of heat with wood furnaces and having the forced air draft is one of them. Setting the thermostat, how much wood to put in and type, outside temp for given day, home during day or gone. Lots of variables in other words. This just gives me another tool for regulating fire.


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## blakey (Jan 4, 2009)

kielbasa said:


> dang salesman! telling me I'd just need to load it up once in the morning and once at night, I should have known better, it does sound too good to be true...
> I actually want it 80 degrees inside my house, that's the beauty of wood heat, how hot you want it?! I remeber having a coronary (looking at the $$$ bill) in one of my other houses when I cranked up the natural gas furnace to keep it nice and toasty, never again!



I don't have any knowledge of the brand you are talking about but I was just giving my experience. If you could get 12hr burn times out of an indoor wood furnace there wouldn't be nearly as many outdoor units sold. I couldn't stand it at 80 degrees for long, the house would get pretty dry. I forgot to turn down the thermostat last night before I went to bed and it was too hot at 72, had to get up to drop it a bit. With the owb and a digital thermostat I get great control. With the indoor wood furnace my wife had a tendancy to load too much wood trying to get a longer burn time but all it would do is cook the house and was hard on the firebox.


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## reaperman (Jan 4, 2009)

kielbasa said:


> ok, bear with me, I'm just trying to get a feel as to how these furnaces are to live with....I'll ask a very general, broad question: do you typically load the thing up with wood in the morning, and the furnace automatically regulates its burn depending on thermostat setting? Raging fire to get up to temp and once it's at or near the thermostat setting, the furnace begins to smolder itself out and just idle until the temp falls and the thermostat calls for it again? And then just reload with wood in the evening once the wood has diminished? Is it a repeating cycle like that? Or more of a constant, even burn (probably depends how drafty the home may be)?
> Like I said, I've never experienced one of these in action, I've just grownup with freestanding wood stoves my entire life (well, my brother has a Juca furnace, incredible furnace, love the fact that it also throws heat downward and drys my wet boots, gloves, keeps the tile floor warm, etc. AND has radiant heat, so the room that it's in is nice and toasty, but his is not thermostatically controlled)...



You hit the nail on the head with your assumption. When the desired temp is hit and the draft fan stops, do you really believe the wood will quit burning, no way! The plenium fan will be running and being the furnace is good and hot it will keep blowing until the wood is pretty much gone, most likely for hours. By that time your home will be much hotter than the thermostat setting and there is nothing you will be able to do about that. But thats wood heat. Thats why I feel you will be able to control the draft manually with whatever kind of draft control comes with the furance. On my unit I use the little sliding door on my draft blower to control the intake draft and thats the most use I get from my draft blower. I too have a new home that is very well insulated. I have large windows, wood floors, open floor plan, and southern exposure, which makes my home very easy to heat and I live in Mn. My trouble is I cant run 24/7 with my furnace, just too hot otherwise. So I have to keep starting fires all of the time when I want heat. Now that I'm home more often this winter, usually light a fire in the morning, and another one after supper.


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## LEES WOODC (Jan 4, 2009)

I have a Meyer which is similiar to the Jack. I burn 3 year dry wood and my draft fan doesn't run much above 20 degrees.When it gets real cold is when the fan is very helpful with keeping a steady heat in the house. Above 30 I shut the draft fan off and use the manual.
I also burn coal and without the fan coal might not burn as well. With the fan there is no guessing about where to set your manual. Just set the thermostat and walk away. I personally woodn't go without a forced draft fan.
Also , if you ever need to burn a little green wood the draft fan is a must.


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## AOD (Jan 4, 2009)

I think the draft fans also cut down on smoke a lot and can help if you have a short chimney, pressure inversions or high winds. Here is how I would control one of these fans. Wire it to a fan/limit temp switch in the plenum through the normally closed limit side. Set this setting to cut the blower off when you reach, say 180* on the plenum, meaning that at this point the fire burns with natural draft. If your plenum drops below that point it will kick back on, meaning the fan only runs when you really need it to. Having it controlled by a wall T-stat is kind of silly.


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## laynes69 (Jan 4, 2009)

The only real safe way to have a draft fan is if its wired into a limit/control. Otherwise you can quickly overfire a unit. Depending on the unit and location of the forced draft, some work some don't. Mines over the fire, when on doesn't hit anything. As far as a draft increaser, not enough cfms to do anything. If you get one under or on the fire thats a different story. They can ramp up a fire within a minute or two. Good for coal. The hotblast units by usstove that have the optional draft kits that mount in the back are a joke. I have one, do i see a difference? Not really. If I would kick it on to start a fire, it would just blow cold air over the fire. When its cold out, and the firebox is loaded, its a different story. Because they can vary on temp control, they recommend you set your central furnace 2 to 3 degrees under your forced draft. Like I say, I have one, its set at 68, but never runs unless its below zero. The only way to have one is if it on a thermostat. That way it won't run till you get to that bottom temperature. I wouldn't have one any other way.


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## Nuzzy (Jan 5, 2009)

blakey said:


> If you could get 12hr burn times out of an indoor wood furnace there wouldn't be nearly as many outdoor units sold...
> 
> ...With the indoor wood furnace my wife had a tendancy to load too much wood trying to get a longer burn time but all it would do is cook the house and was hard on the firebox.





Fwiw, our indoor furnace with a thermostat controlled damper can pretty regularly burn 11 hours maintaining 67-69* in the 1800sq ft main floor ranch and still have good enough coals in the morning to easily continue burning when above 0*F outside throughout the night. I lust load it with two or three 8-12" X 16" rounds and a split or two each night before bed. I haven't once had to wake up in the middle of the night to load wood. Now because of the smoldering, I'll usually force the damper open for a while in the morning even if the house is at temp just to bake off the creosote, but that's just preventative maintenance.


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## CowboyAndy (Jan 5, 2009)

laynes69 said:


> The only real safe way to have a draft fan is if its wired into a limit/control. Otherwise you can quickly overfire a unit. Depending on the unit and location of the forced draft, some work some don't. Mines over the fire, when on doesn't hit anything. As far as a draft increaser, not enough cfms to do anything. If you get one under or on the fire thats a different story. They can ramp up a fire within a minute or two. Good for coal. The hotblast units by usstove that have the optional draft kits that mount in the back are a joke. I have one, do i see a difference? Not really. If I would kick it on to start a fire, it would just blow cold air over the fire. When its cold out, and the firebox is loaded, its a different story. Because they can vary on temp control, they recommend you set your central furnace 2 to 3 degrees under your forced draft. Like I say, I have one, its set at 68, but never runs unless its below zero. The only way to have one is if it on a thermostat. That way it won't run till you get to that bottom temperature. I wouldn't have one any other way.



We have a thermostaticly controlled draft fan on our furnace, and it does a surprisingly good job at regulating the temp. But, you have to consider that it still takes skill for efficiant burning, ie how much and how often you put wood in. if the house is 73 and the tstat is set to 75 and i fill it up then ya, the house is going to go up o 76-78.

But I am pretty happy with what it does. 

One of the biggest benifits IMO is that the fan keeps the smoke in the forebox during startup and reloading, as opposed to spilling into the house.


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## smokinj (Jan 5, 2009)

I have one and dont use it that offten!(if i had to do it again i would go without one)


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## laynes69 (Jan 5, 2009)

I don't see what a forced draft has to do with smoke in a home. If the chimney is setup and the furnace with proper draft, there should never be any smoke spillage into a room. I have never had this issue. Alot of people when they come here can't tell we burn wood. I say whys that? They don't smell it. A dirty chimney, a partially clogged flue, or a short chimney can cause that problem, but it shouldn't smoke when opening the door if everything is up to par. Sounds more like a low draft.


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