The positives of NOT having an OAK.

[Harvey Schneider]

How come Oil furnaces and Gas furnaces don't have oaks ......

Good question.
Builders are too cheap to front the cost of it and the oil companies (and this includes the small local guy) have a conflict of interests. Not selling you an OAK allows them to sell you more oil. They should also install an oil vent damper on the flue, but that costs up front and saves oil also.
An OAK (they refer to it as a fresh air kit) for my Beckett burner retails for about $150 additional tube and vent cap are about another $50 to $75. The local oil dealer wants $900 for it, installed. Installation is a piece of cake, maybe 45 minutes of work.
Oil vent dampers can also be had for about $150, retail. Installation involves some wiring.

 

[XXV-AK]

M

How come Oil furnaces and Gas furnaces don't have oaks ......

FYI My new Tran natural gas furnace 95% efficiency rating has a OAK

 

[brack86svo]

Do you have concern over creosote buildup or condensation since the exhaust temps are dropped?

Not sure I could do a Selkirk, as it would be almost 40' - I imagine that's expensive, and I would be concerned with exhaust temps dropping too much for that length of run.

I eliminated creosote buildup when I installed mine. I would get bad buildup in the flue and on the glass before I put it in.

 

[jlupi]

the combustion fan going all the time has done wonders for my wintertime high humidity problem without the annoyance of having a bath fan going constantly or the larger draft of an open window.

 

[N.E S4]

Cold air burns better it is more density, more oxygen.

 

[Jason Knapp]

How come Oil furnaces and Gas furnaces don't have oaks .....

I know that code in the 12603 is that all new furnace installs have an OAK. That being said, I bet my furnace could benefit from an OAK.

 

[XXV-AK]

I know that code in the 12603 is that all new furnace installs have an OAK. That being said, I bet my furnace could benefit from an OAK.

Thanks for the insight . Anthony Knapp AK

 

[lessoil]

We have this discussion at work every once in awhile. We have an OAK and my co-worker does not.
Besides the creation of drafts the other thing that comes to mind is this:
Does it make sense to heat the the air in the house only to throw it outside after used for combustion?

But I do have a concern using real cold air from outside. Does it cool the burn pot down vs no OAK??

Happy Burning!

 

[Harvey Schneider]

I did the math, and if I didn't make any mistakes, it takes 0.000117 lbs of pellets per minute to raise 0 degree air entering at 130 cfm to the 70 degrees it would have been if room temperature air was used instead of outside air. That is less than 0.005 cu inches of pellets per minute.That would be 7.3 cu inches (that's about 1/2 cup) per day if it runs non-stop.
To put it plainly, the amount of chemical energy in wood is enormous compared to the energy it takes to warm 130 cu ft of air by 70 degrees F. It won't be noticed. Besides, if the air was drawn from the house, the zero degree air would leak in somewhere else and still have to be heated to 70 degrees.
Hot burn pot and cold house or Hot burn pot and warm house, take your pick!

 

[mepellet]

I did the math, and if I didn't make any mistakes, it takes 0.000117 lbs of pellets per minute to raise 0 degree air entering at 130 cfm to the 70 degrees it would have been if room temperature air was used instead of outside air. That is less than 0.005 cu inches of pellets per minute.That would be 7.3 cu inches (that's about 1/2 cup) per day if it runs non-stop.
To put it plainly, the amount of chemical energy in wood is enormous compared to the energy it takes to warm 130 cu ft of air by 70 degrees F. It won't be noticed. Besides, if the air was drawn from the house, the zero degree air would leak in somewhere else and still have to be heated to 70 degrees.
Hot burn pot and cold house or Hot burn pot and warm house, take your pick!

Approx 9800 BTUs per hour to raise 130 cfm by 70 degrees f. Or 163 BTUs per minute.

 

[SwineFlue]

I did the math, and if I didn't make any mistakes, it takes 0.000117 lbs of pellets per minute to raise 0 degree air entering at 130 cfm to the 70 degrees it would have been if room temperature air was used instead of outside air. That is less than 0.005 cu inches of pellets per minute.That would be 7.3 cu inches (that's about 1/2 cup) per day if it runs non-stop.
To put it plainly, the amount of chemical energy in wood is enormous compared to the energy it takes to warm 130 cu ft of air by 70 degrees F. It won't be noticed. Besides, if the air was drawn from the house, the zero degree air would leak in somewhere else and still have to be heated to 70 degrees.
Hot burn pot and cold house or Hot burn pot and warm house, take your pick!

I bet it's even less than that. A 130 cfm intake seems high to me.
If 130 cfm is at the combustion blower:
A) I think(!) the exhaust is mostly combustion gases (burned pellets)
B) It has been heated hundreds of degrees, greatly expanding the cubic feet vs what came in at the intake

 

[DexterDay]

I bet it's even less than that. A 130 cfm intake seems high to me.
If 130 cfm is at the combustion blower:
A) I think(!) the exhaust is mostly combustion gases (burned pellets)
B) It has been heated hundreds of degrees, greatly expanding the cubic feet vs what came in at the intake

Most combustion blowers are only 80 CFM on Full Blast. So most the time, its less than that.

 

[DneprDave]

My oil burner is under the house, in an uninsulated crawlspace. There is an outside vent about every eight feet around the foundation, is that enough fresh air for ya!?

My sister had a new gas furnace installed, they ran a duct for an outside air supply for the new furnace. Her furnace is in an insulated garage.

My pellet stove heats a glassed in porch that would be very difficult to seal up tight, but I only use about 3/4 of a bag of pellets a day to keep it warm, I don't think an OAK would do me any good. I don't feel any drafts out on the porch anyway.

Dave

 

[Jack Morrissey]

I did the math, and if I didn't make any mistakes, it takes 0.000117 lbs of pellets per minute to raise 0 degree air entering at 130 cfm to the 70 degrees it would have been if room temperature air was used instead of outside air. That is less than 0.005 cu inches of pellets per minute.That would be 7.3 cu inches (that's about 1/2 cup) per day if it runs non-stop.
To put it plainly, the amount of chemical energy in wood is enormous compared to the energy it takes to warm 130 cu ft of air by 70 degrees F. It won't be noticed. Besides, if the air was drawn from the house, the zero degree air would leak in somewhere else and still have to be heated to 70 degrees.
Hot burn pot and cold house or Hot burn pot and warm house, take your pick!

Isnt the cold air going to leak in anyways, regardless whether you have an Oak or not??

 

[StihlHead]

My pellet stove heats a glassed in porch that would be very difficult to seal up tight, but I only use about 3/4 of a bag of pellets a day to keep it warm, I don't think an OAK would do me any good. I don't feel any drafts out on the porch anyway.

Dave

Actually a small drafty area is where you get the most benefit from having an OAK. The reason being that the draw of air in a smaller area can be as high as one turnover an hour from the stove. Put in an OAK and you would cut the turnover rate way down, and feel a lot more heat.

 

[StihlHead]

Isnt the cold air going to leak in anyways, regardless whether you have an Oak or not??

Cold air will leak in, stove or no stove. However, the stove will draw that much more cold air in on top of the natural drafts. In a smaller heated area, the greater the effect of the stove draft on air turnover and the greater the benefit of adding an OAK to reduce the added stove draft air turnover.

 

[mepellet]

Actually a small drafty area is where you get the most benefit from having an OAK. The reason being that the draw of air in a smaller area can be as high as one turnover an hour from the stove. Put in an OAK and you would cut the turnover rate way down, and feel a lot more heat.

80 cfm and 8 foot ceilings would create 1 air change per hour in a 600 square foot space.

 

[john193]

If the savings with an oak were significant, it would likely be more commonly used. While I don't disagree it makes common sense, the savings appear to be minimal.

 

[StihlHead]

If the savings with an oak were significant, it would likely be more commonly used. While I don't disagree it makes common sense, the savings appear to be minimal.

Generic statements like this make my skin crawl.

 

[SmokeyTheBear]

The savings are proportional to the heat loss prevented and can be estimated to some degree once you know the lowest combustion air flow rate which is usually around 80% of the rated CFM of the blower and don't mind a little estimation.

The loss is a fraction of a pound of pellets per hour and can easily reach a 1/4 to 1/2 bag per day once heating season is really under way. You have to get down the the actual stove's efficiency and combustion air flow per day and the actual pellet being burned to nail it any closer than that.

 

[john193]

Generic statements like this make my skin crawl.

Well I didnt mean to excite you. While I'm seriously considering adding an OAK to my system as well, being on this site has given me a better understanding, all the while adding to more questions. For example, Quadrafire stoves do not come with a sealed intake system. So how can one determine how much the stove is pulling from the OAK versus the immediate room air? And by cutting a 3 inch diameter hole to the outside, am I now introducing more cold air than the stove needs; thereby cooling the house?

My statements are no more or no less generic (i.e. feelings) than someone arguing that they feel warmer because they put an OAK in. We can run theoretical calculations all day, but without a controlled study I'm not falling head over heals about the idea (research science for the past 6 years will do that). I'm listening and trying to educate myself by being here. The exhaust output of a stove is simply a small piece of the thermal puzzle. Perhaps I could save just as much in pellets as someone with an OAK by letting my dog out half the time I do now.

 

[Don2222]

How come Oil furnaces and Gas furnaces don't have oaks ......

They sure do! Here are pics of my Carlin Air Boot!
https://www.hearth.com/talk/threads...ystem-carlin-or-becket-burner-air-boot.52869/

 

[DexterDay]

Well I didnt mean to excite you. While I'm seriously considering adding an OAK to my system as well, being on this site has given me a better understanding, all the while adding to more questions. For example, Quadrafire stoves do not come with a sealed intake system. So how can one determine how much the stove is pulling from the OAK versus the immediate room air? And by cutting a 3 inch diameter hole to the outside, am I now introducing more cold air than the stove needs; thereby cooling the house?

My statements are no more or no less generic (i.e. feelings) than someone arguing that they feel warmer because they put an OAK in. We can run theoretical calculations all day, but without a controlled study I'm not falling head over heals about the idea (research science for the past 6 years will do that). I'm listening and trying to educate myself by being here. The exhaust output of a stove is simply a small piece of the thermal puzzle. Perhaps I could save just as much in pellets as someone with an OAK by letting my dog out half the time I do now.

Quads are a little "Leaky". Yes... But.... The air will take the path of least resistance. Given the opportunity to come down the 2.5" OAK or come through your bedroom window 30' away? Its gonna come down the OAK.

I sealed mine up pretty darn good. Its probably about 90%-95% sealed now. Its not hard. Find the intake path, find the cracks and leaks, add a little high temp silicone or foil tape and your good to go
.
All 3 of my stoves have OAKs now. I did the Quad almost immediately (yrs ago). I just added the Wood eater and Pellet furnace last season. I didn't add the OAK until this year. To see the results with and without! Pretty remarkable. IMO.

OAKs work. Period. Your gonna pull that cold air in somewhere. Through your bedroom or through the OAK? You decide

 

[save$]

I'm not up to the math. Makes my head spin. My way to reason this is to go to you stove's exhaust vent. Feel the strong breeze. You know that without OAK, that air is being sucked into the stove using air you paid to heat in that room. Air out is replaced with air in. That same volume of air you feel being blow out creates neg. pressure that is replaced by air being sucked into the house from outside at outside temps. So you are paying to heat air that your stove is exhausting out. You may as well have your bathroom vent fan in reverse! All those heating units put in years ago were done in a time when fuel was cheap and homes were no where near as well insulated and airtight.
I had one sales person tell me that the reason they don 't encourage Use of the OAK is that when the stove in't in use that the OAK cools off the house quickly. How lame is that!

 

[StihlHead]

If the savings with an oak were significant, it would likely be more commonly used.

Yes, old paradigms are hard to change. Its human nature. However, just because things are a certain way is not a good indicator of its effectiveness. In actuality OAKs are becoming far more common now, and in many cases they are required by code for all heating devices that draw air for combustion. Most newer wood stoves are not sealed to the OAK because the EPA requires warm air intakes for the gassifier air injection systems and they do not want you to be able to completely damp down the stoves like you can with the old smoke dragons. It takes some doing to overcome some of these required design features and in many ways the EPA has gone out of its way to defeat the purpose of the OAK by requiring that non-cat stoves be ducted the way that they are. However, in all cases, the stove or combustion appliance will draw in air from someplace and send it up the flue.

Fortunately the OAK paradigm is changing. I was at the local Farm and Ranch store the other day and the sales guy there was selling a stove and pushing the buyer hard to install an OAK. I smiled hearing that.