I did a search and wasn't able to find a thread on the subject, but did see several threads about stove operation that talked a little about it. I'm trying to gather information on pros and cons of outside air and any first hand experience. We have a newly built house that is fairly air tight and well insulated. I've had several discussions with a coworker about outside air and he swears by it. Our stove seems to perform well and doesn't seem to be starving for air. We didn't put outside air piping in when we built, but it wouldn't be a major issue to add a line down our hallway wall from the attic to gain access to outside air from the roof. So, would you all share some about your experiences and what you know as pros and cons?
Outside Air vs Room Air
- Thread starter okiesmoker
- Start date
-
Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.
We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.
We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil. -
Super Cedar firestarters 30% discount Use code Hearth2024 Click here
BigFir
Burning Hunk
I don't know much about OAK's but I don't think it is recommended to pull air from much above the stove........The roof may not work well. I'm sure others will be along to help you out.
iron
Minister of Fire
there are some other sites out there that if you google your question, have their opinions.
i think the biggest issue with using/not using an OAK is the airtightness of your home. if it's very tight, an OAK is a must. if not, then it's your call.
in general, it would seem prudent, to me, to draw air from a dedicated source rather than from the gaps and cracks in your house. i believe one stove/fireplace MFR calls this posi-pressure: basically pressurizing your house with warm air. if you don't have an OAK, i suspect you would feel drafts as the stove draws cold air from all the cracks, though perhaps that has a side benefit of mixing your air throughout your house better.
i think the biggest issue with using/not using an OAK is the airtightness of your home. if it's very tight, an OAK is a must. if not, then it's your call.
in general, it would seem prudent, to me, to draw air from a dedicated source rather than from the gaps and cracks in your house. i believe one stove/fireplace MFR calls this posi-pressure: basically pressurizing your house with warm air. if you don't have an OAK, i suspect you would feel drafts as the stove draws cold air from all the cracks, though perhaps that has a side benefit of mixing your air throughout your house better.
Sprinter
Minister of Fire
Where is your stove in the house? I'm a big advocate of OAK, but it should be properly installed and placed. The intake should be sheltered from any wind, for example. If your stove is on a floor above a ventilated crawlspace, you may find a way to get the duct through the floor and screen it from critters (what we have). Otherwise, if the stove is near an outside wall, you can find an OAK kit that can protect the intake from the wind on the outside wall. I wouldn't try to run the duct too far.
Depending on the difficulty of installing (properly) the duct, you may get along okay without it. What usually happens with a tight house is that using appliances that exhaust to the outside such as bathroom fans, furnaces, clothes dryers, etc, can cause enough negative pressure in the house that it can kill the chimney draft and suck smoke in or just make for a poor fire.
Depending on the difficulty of installing (properly) the duct, you may get along okay without it. What usually happens with a tight house is that using appliances that exhaust to the outside such as bathroom fans, furnaces, clothes dryers, etc, can cause enough negative pressure in the house that it can kill the chimney draft and suck smoke in or just make for a poor fire.
I marked the spot the stove is in the house in the attached. It would be a bit of a run to get to an accessible exterior wall. So far, I've not noticed any issues with the performance of the stove during the typical negative pressure type events.
![[Hearth.com] Outside Air vs Room Air](https://www.hearth.com/talk/data/attachments/191/191017-cbfed9e1a001f164e6bbfe0a46cd3ec2.jpg?hash=KQL4JR646G "[Hearth.com] Outside Air vs Room Air")
BigFir
Burning Hunk
If you don't notice an issue with back puffing or spillage I wouldn't sweat it....
Sprinter
Minister of Fire
I would agree. Just keep an eye on things and if you experience trouble, then you can go from there. Occasionally, you may need to open a window or something to help the draft. If you discover an easy OAK access, fine.. That would be best.
How to install a wood stove with No Oak:
- Cut a 3" hole in your bedroom wall to the outside
- Install 3" muffin fan so that it blows inside; must be +150 cfm fan; preferably +350 cfm
- Turn on fan whenever the outside temp is below 30 degrees or so.
Now, I ask you: What kind of idiot would do that in their home, especially if they live in the cold part of the country (i.e. north of TN)?
Well, that's what you're doing if you have a wood stove with no OAK.
Still sound like a good plan?
Yea neither did I. Pro installer bitched but did it anyway since I was the one writing the check.
- Cut a 3" hole in your bedroom wall to the outside
- Install 3" muffin fan so that it blows inside; must be +150 cfm fan; preferably +350 cfm
- Turn on fan whenever the outside temp is below 30 degrees or so.
Now, I ask you: What kind of idiot would do that in their home, especially if they live in the cold part of the country (i.e. north of TN)?
Well, that's what you're doing if you have a wood stove with no OAK.
Still sound like a good plan?
Yea neither did I. Pro installer bitched but did it anyway since I was the one writing the check.
electrathon
Minister of Fire
BigFir
Burning Hunk
Yes it is. But keep in mind all that air is usually spread out here and there. Some setups may not be able to overcome the drafts and some can. I really can't burn 24/7 until it hits -15c to -20c in a 40 year old 3000sq/ft house with 10 year old windows, but leaky doors, it just gets too hot.
I would like to have an OAK but it would be hard to set up with out a lot of work and it would look ridiculous in my situation.
Sometimes the cons can out way the pros..... every situation is different.
Just my thoughts.....
So, if I were to add OAK, can I go up through the roof or do I need to stay near ground level and make my way through the hallway wall and on to the outside on the back patio?
My husband & I have been discussing this off n on all day. We are about to replace our Napoleon 1100 with an Alderlea T6 and trying to decide if we should use an OAK. Currently we do not. Replacing the Napoleon because it can't keep up with our 1880's drafty old house. Would outside air to current stove helped?
There must be over 1000 posts here on outside air supplies. I'd suggest you try some different search words - "oak" springs to mind.
I wouldn't run a wood stove in a "tight" house without one. Consider the scenario where some or all your air exhausting systems happen to operate simultaneously: range hood, dryer, exhaust fans, water heater, etc. Do you really want your CO producing stove back-drafting into your living space?
It's probably unlikely. From the description it sounds like heat loss is the main issue. Sealing up leaks should also be a priority. We sealed the sill plate and caulked all the joist cavities to stop leakage below our floors. Also insulated and sealed all the ductwork. It really helped. FWIW we don't have an OAK on our T6 in a 1924 farmhouse. No issues to report.
Thanks, planning to remodel in the next year so we'll be sealing things up! Looking forward to new stove....
Maybe not ...I forgot to account for the fan area... ~9 in square.. With a 350 cfm thats 350x9/144=21 cfm... about what I thought a stove used
If it is burning well as is, you have your answer. Load her up, and enjoy.
Karl Hungus
New Member
Am building a new very tight energy efficient home. We have a masonry heater built in it and after going round and round about this we decided to go without any make up air.
Do you have a blower door test done on the house after it was built?
What was the ACH or cfm leakage?
That will tell you how much air is coming in.
Do you have a erv/hrv? You can run that when the stove is on and that will cure your problem.
Also do you have any exhaust fans that go to the outside? Like a range hood over the stove or bath fans or a dryer vent?
Worse case run all these items and then check the stove when its not in use and see if there is a back draft. If there is no back draft then your good to go.
Do you have a blower door test done on the house after it was built?
What was the ACH or cfm leakage?
That will tell you how much air is coming in.
Do you have a erv/hrv? You can run that when the stove is on and that will cure your problem.
Also do you have any exhaust fans that go to the outside? Like a range hood over the stove or bath fans or a dryer vent?
Worse case run all these items and then check the stove when its not in use and see if there is a back draft. If there is no back draft then your good to go.
No, there wasn't a test done. What is an erv/hrv? Yes, we have a vent hood, bath fans and dryer vent.
A blower door test won't tell you what you need to know. You can have leaks, but until you have leaks AND an appliance putting a suction in your home you won't necessarily have flow through the leaks.
Always use outside air for the stove unless you have a significant obstacle in the way. Burning inside air means pumping outside air into the home along with all the dirt, and with the very low humidity that cold outdoor has in the winter.
The intake for the outside air must be below the firebox. You don't want your intake duct to make a better chimney than your chimney. Folks in basements sometimes run the outside air duct up to grade level but have a very tall chimney to hopefully win the fight.
Always use outside air for the stove unless you have a significant obstacle in the way. Burning inside air means pumping outside air into the home along with all the dirt, and with the very low humidity that cold outdoor has in the winter.
The intake for the outside air must be below the firebox. You don't want your intake duct to make a better chimney than your chimney. Folks in basements sometimes run the outside air duct up to grade level but have a very tall chimney to hopefully win the fight.
My home is very air-tight (final blower door test 0.8 ACH50). I have an OAK for the small stove in the lower level. If I go to light the stove when the clothes dryer or range hood is running, the stove backdrafts, forcing me to scramble to open a window, then run upstairs to kill the exhausting device. I get smoke out past the door seal and around some small cracks or openings around the air control mechanisms, despite the OAK direct connection. Once I get the stove fired up well, with hot flue gas running up the chimney, that draft through the OAK duct and up turns the stove into a minor exhausting device, able to compete with the dryer or hood, so those can go back on.
The house also has an HRV (heat recovery ventilator, basically an air-to-air heat exchanger) to provide fresh air for the house, something really required for a very tight house. Operating an exhausting device, like dryer or hood, makes the HRV run out of balance, as those devices compete with the fan exhausting interior air out through the HRV. I perhaps could run the stove without an OAK, as long as there was nothing to compete with it for air. I suspect I'd have trouble with backdrafting as soon as I ran some other device.
My advice for a new house built to be very tight: add the OAK, and pick a stove that lets you connect the duct directly to the stove. I rejected one stove after the mfg confirmed that there was no direct connection, and that the OAK duct would just dump raw outside air "into the vicinity of the stove," as in all night long after I let the stove burn out. Uh-uh, not in my tight, superinsulated house.
Similar threads
