to OAK or not to OAK

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kurthood

Member
Jan 27, 2011
24
southern NH
Hello Forum,

This is my first post to this site. I've done a fair amount of reading so far, and it seems like a great collaboartion here. Specifically, I've been reading about outside air kits and whether or not to install one for my own stove setup. so here goes.

It seems like there are some pro's and cons to each. Currently, I do not have an OAK installed for my harman P61A. There is a natural convection in the house at this point because its burning the air in the house of course. I have a fan positioned at the top of the basement stairs pulling the cold air from the main floor down into the basement where the stove is located. There seems to be a steady loop of cold air going down and warm up rising up from the basement.

One of my main concerns was of course the CO levels. I guess its technically possible to burn all of the available O2 in the house and eventually draw a reverse draft down through the chimney correct ? Realistically though, could this ever happen with the blower on the stove constantly pushing exhaust, and the various leaks in the house pulling in some amount of cold air ? Like I mentioned, the stove is in the basement and there a few of those cheap rectangular basement windows just next to it, and they feel pretty leaky. Today I'm going to pick up some digital CO monitors just to keep alittle closer eye on it.

On the other hand, there is the debate that by not having an OAK you are burning and exhausting the air that the stove has already heated so its fairly wasteful. But the air being pulled down the basement stairs is always cold. Not like its pulling 70 degree air down to the stove to be burned and sent out the chimney. Would the stove burn better/hotter/more efficiently if it had its own air source from outdoors.? Its pretty cold outside these nights (single digits, teens, etc) so would the stove have to work harder to heat this cold of an air source ?

It seems like having an OAK is dependent on each individual set up. Safety and efficiency are really my top concerns, so I guess whatever satisfied those two the best would help me make my decision.

Any advice or input from the veteran pellet stove users here would be greatly appreciated. Thanks !!!
 
I have had four pellet stoves (two Whitfields and two Harman's). I have talked with several "experts" (those that install stoves professionally about OAK's.) Bascially they have said the same thing......in nine out of ten homes, you do not need an OAK. I told them that Harman recommends an OAK in the install manual. The dealers countered that they have literally installed hundreds of stoves and they know whether one is needed or not.

I do have an OAK installed on my P-38 Harman which is located in the basement. The reason for this is the basement is fairly airtight. I do not have an OAK installed on my Accentra Harman insert located on the first floor. Two dealers advised I did not need it. The stove runs great without it.

I did not have OAK's installed on either of my Whitfields either.

The jury is still out on OAK's. My opinion is that in most cases, you don't need one unless your house is fairly "airtight."
 
aside from costing you some in parts and such, I cannot think of a "con" to OAK. Certainly couldn't hurt, though you're not likely to see some "dramatic" change in the operation of the stove, in most cases. you may not "need" it, but if you want it, do so.
 
Those 9 out of 10 houses that don't need the Oak. Don't need it because they are pulling that cold air in from every nook and cranny to satisfy the needs of the stove. You can pull it in thru the OAK and keep that warm air. OR you can blow your warm air out the flue and draw colder air in your kitchen, bedroom, bathroom, outlet covers on exterior walls. Everyone has there reasons to OAK or not to OAK. Everyone's situation is different. And just cause this is what I do, does not mean you should. You asked for an opinion and this is mine. I would rather pull my cold air into the stove, rather than into my bedroom.
 
After listening to my wife groan (imagine that :) ) about the 'drafts' around the Castile, I spent the day today hooking up an OAK into my ash dump in my fireplace. I had to fabricate the mounting plate and reduce a 3" flanged crimped fitting down to 2" and mate them together and mount them. Then I used some SEMI-flexible steel ducting I got from McMasterCarr. It gave me the most trouble because of the wide radius bends I had to take. Worst part was that it's an insert and inserts are a PITA to do anything with. And the surround on the Castile is NOT a one man job and just BARELY a husband and wife job. I lost a lot of blood biting my lip during that fiasco.

In any event, it's hooked up except for putting wire mesh in the ash dump opening to keep the critters out. Since I have to wait for the 500 degree silicone to set up, I can put the mesh off until tomorrow. One down and one to go. The other one is going to be even more fun because I have to run the OAK up the chimney and out the top with a 180 degree turn. That means a trip to the roof. While I'm up there, I have a bucket of Crown Seal waiting for the top of the chimney too. I'll probably make that OAK 3" because it's a long run. The Sante Fe leaves very little room to make a 90 degree turn from the side of the air inlet to the back of the stove so I'm not real sure what to do. It's going to take a tight radius. I thought of getting a street ell if you plumbers know what I mean, and weld a bracket to it.

Well, that lowers my 'honey do' list down to about the National Debt........
 
Cincinnati Kid said:
.....I have talked with several "experts" ......Bascially they have said the same thing......in nine out of ten homes, you do not need an OAK. I told them that Harman recommends an OAK in the install manual. The dealers countered that they have literally installed hundreds of stoves and they know whether one is needed or not....

Yep, why would anyone want to listen to the company that made the stove. The "experts" always know more.

You keep sending the heated air up your exhaust, and keep pulling cold air through the cracks & crevices of your home.....I'll keep my heated air inside. :smirk:
 
tjnamtiw-

I've got a Quad Mount Vernon AE that needs an OAK through the chimney because of the wife complaining about drafts. Please let us know what your wife thinks after you do all that hard work!

Thanks!
 
OAK in chimney with blue stone cap.
 

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FMT, I bet I know where that 180 degree pipe came from! Looks like about the diameter from a diesel truck. I was thinking about visiting my local muffler shop. :) How tight a radius can you put on 2" pipe? And 3"?
 
Daves said:
tjnamtiw-

I've got a Quad Mount Vernon AE that needs an OAK through the chimney because of the wife complaining about drafts. Please let us know what your wife thinks after you do all that hard work!

Thanks!

I will. She BETTER like it or I'll .......................................... shut up and do another honey do real quick...... %-P
 
tjnamtiw said:
FMT, I bet I know where that 180 degree pipe came from! Looks like about the diameter from a diesel truck. I was thinking about visiting my local muffler shop. :) How tight a radius can you put on 2" pipe? And 3"?
Close but most of the diesels I am working on now have 3.5 to 4 inch exhaust unless you want to count in my friends Peterbilt 379, thats got 7 inch. I wanted to chrome plate it but the wife said no.
I got my U bent from a local speed shop, automotive parts not the other kind of speed shop.
Not many muffler shops around can bend 3 inch and if so I doubt they have a mandrel type bender that will not squash the pipe when it's bent. If I am not mistaken this is what I used.
http://www.streetperformance.com/part/hooker-headers/exhaust-pipe/314587-12280.html
 

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That's PERFECT, MFT!!!!!! Going to order one right away! Good info on muffler shop capabilities too. With the good ole boy shops around here, who knows what I'd get! AND I'd still pay that much after they spoiled 4 to get one good one.
 
I don't have an oak, but I wish I did. Might was well get it installed, then you can disconnect from it to test it out.

Going to install or get one installed at some point, once I can accept cutting another hole in an outside wall. My dad has an oak which "conditions" the air by mixing it around the outside of the vent thimble.

I have a drafty farm house, the experts said "you don't need one", I disagree... i can feel it pulling cold air through the floor, and while that might happen anyway, the lack of an oak simply makes it worse.
 
mpcm said:
I don't have an oak, but I wish I did. Might was well get it installed, then you can disconnect from it to test it out.

Going to install or get one installed at some point, once I can accept cutting another hole in an outside wall. My dad has an oak which "conditions" the air by mixing it around the outside of the vent thimble.

I have a drafty farm house, the experts said "you don't need one", I disagree... i can feel it pulling cold air through the floor, and while that might happen anyway, the lack of an oak simply makes it worse.

Selkirk makes a pipe that you can buy to do the same thing. Outside air is pre-heated around exhaust gas. (Add is at the bottom of every page on this forum).
Or Simpson/Duravent makes a wall thimble that you can buy to replace yours. It has 2 holes in it, so you don't have to Separate holes. Just a thought. Think I seen the Simpson kit online for about $90. That included the thimble with both holes and 3' of flex pipe and clamps.
 
FordMastertech said:
tjnamtiw said:
FMT, I bet I know where that 180 degree pipe came from! Looks like about the diameter from a diesel truck. I was thinking about visiting my local muffler shop. :) How tight a radius can you put on 2" pipe? And 3"?
Close but most of the diesels I am working on now have 3.5 to 4 inch exhaust unless you want to count in my friends Peterbilt 379, thats got 7 inch. I wanted to chrome plate it but the wife said no.
I got my U bent from a local speed shop, automotive parts not the other kind of speed shop.
Not many muffler shops around can bend 3 inch and if so I doubt they have a mandrel type bender that will not squash the pipe when it's bent. If I am not mistaken this is what I used.
http://www.streetperformance.com/part/hooker-headers/exhaust-pipe/314587-12280.html

One question >> is that U bend 3" OD so that 3" ID flex can fit over it? What kind of flex did you use for the OAK? We don't really need the expensive stuff, just heat tolerant. Ooops, that's 2 questions...
 
tjnamtiw said:
FordMastertech said:
tjnamtiw said:
FMT, I bet I know where that 180 degree pipe came from! Looks like about the diameter from a diesel truck. I was thinking about visiting my local muffler shop. :) How tight a radius can you put on 2" pipe? And 3"?
Close but most of the diesels I am working on now have 3.5 to 4 inch exhaust unless you want to count in my friends Peterbilt 379, thats got 7 inch. I wanted to chrome plate it but the wife said no.
I got my U bent from a local speed shop, automotive parts not the other kind of speed shop.
Not many muffler shops around can bend 3 inch and if so I doubt they have a mandrel type bender that will not squash the pipe when it's bent. If I am not mistaken this is what I used.
http://www.streetperformance.com/part/hooker-headers/exhaust-pipe/314587-12280.html

One question >> is that U bend 3" OD so that 3" ID flex can fit over it? What kind of flex did you use for the OAK? We don't really need the expensive stuff, just heat tolerant. Ooops, that's 2 questions...
Most if not all automotive exhaust piping is OD and the link states that this U bend is 3 inch OD.
I used the semi rigid flexible aluminum ducting available from Lowe's or Home Depot and it was 3 inch ID.
 
Great. Thanks, MFT! I was heading to HD tomorrow anyway! My cordless drill went up in a ball of flames today! I was just about to order 2 new batteries for it! Good ole Made in China Craftsman crap!
 
tjnamtiw said:
Great. Thanks, MFT! I was heading to HD tomorrow anyway! My cordless drill went up in a ball of flames today! I was just about to order 2 new batteries for it! Good ole Made in China Craftsman crap!

DeWalt... Only way to go. 18v XRP cordless hammer drill. Got mine in 6 piece kit over 4 yrs ago and shown it hell. Just used it for a couple hrs this evening, framing and building a new closet (pellet bunker) in the basement. Should hold at least 6 ton.
 
DexterDay said:
tjnamtiw said:
Great. Thanks, MFT! I was heading to HD tomorrow anyway! My cordless drill went up in a ball of flames today! I was just about to order 2 new batteries for it! Good ole Made in China Craftsman crap!

DeWalt... Only way to go. 18v XRP cordless hammer drill. Got mine in 6 piece kit over 4 yrs ago and shown it hell. Just used it for a couple hrs this evening, framing and building a new closet (pellet bunker) in the basement. Should hold at least 6 ton.

I agree! When this one blew up in my face, I pulled out the Dewalt corded one and got on with the job! The Craftsman did see hell though driving 25 pounds of decking screws one weekend! :cheese: Can't complain too much because it's been around for many years. I WILL be looking at DeWalt though this time.
 
Thanks for the replies everyone,

It seems from everyones replies that the OAK certainly doesn't hurt to have it installed. It makes sense to be burning and exhausting cold air from outside rather than exhaust the air you've already heated to some degree. It will be interesting to see how much of a difference it makes when the stove has its own air source independent from the house air. Do you guys find theres still good convection in the house with cold air sinking to the stove, and warm air creeping upwards ? I wonder if the stove would still create that convection because its no longer drawing the cold air from within the house. Time to experiment I guess. Thanks again.
 
DexterDay said:
tjnamtiw said:
Great. Thanks, MFT! I was heading to HD tomorrow anyway! My cordless drill went up in a ball of flames today! I was just about to order 2 new batteries for it! Good ole Made in China Craftsman crap!

DeWalt... Only way to go. 18v XRP cordless hammer drill. Got mine in 6 piece kit over 4 yrs ago and shown it hell. Just used it for a couple hrs this evening, framing and building a new closet (pellet bunker) in the basement. Should hold at least 6 ton.

Oh, come on now Dexter....don't buy a toy when you need a tool ;-)

www.milwaukeetool.com/tools/cordles...less-1-2-inch-hammer-drill-driver-kit/2602-22
 
In response about the original question of pulling CO2 back into the house through the exhaust... since the unit is under constant negative pressure due to the exhaust blower it won't be possible for this to happen so long as the blower is on. Of course if the blower shuts down then it could be possible for reverse drafting to occur where the chimney is now acting as your "oak" and your air inlent is acting as your chimney. I've only heard of this and never seen it happen.
 
kurthood said:
Thanks for the replies everyone,

It seems from everyones replies that the OAK certainly doesn't hurt to have it installed. It makes sense to be burning and exhausting cold air from outside rather than exhaust the air you've already heated to some degree. It will be interesting to see how much of a difference it makes when the stove has its own air source independent from the house air. Do you guys find theres still good convection in the house with cold air sinking to the stove, and warm air creeping upwards ? I wonder if the stove would still create that convection because its no longer drawing the cold air from within the house. Time to experiment I guess. Thanks again.

I, but not my wife, fully expect to still feel a draft. After all, it's a space heater pulling in room air at the floor level and exhausting it up high. How could there not be a circulation of air? But, of course, that bridge will be crossed AFTER I spend countless death- defying hours on the roof plus who knows how many trips up and down to carry every tool I own up there!
 
imacman said:
DexterDay said:
tjnamtiw said:
Great. Thanks, MFT! I was heading to HD tomorrow anyway! My cordless drill went up in a ball of flames today! I was just about to order 2 new batteries for it! Good ole Made in China Craftsman crap!

DeWalt... Only way to go. 18v XRP cordless hammer drill. Got mine in 6 piece kit over 4 yrs ago and shown it hell. Just used it for a couple hrs this evening, framing and building a new closet (pellet bunker) in the basement. Should hold at least 6 ton.

Oh, come on now Dexter....don't buy a toy when you need a tool ;-)

www.milwaukeetool.com/tools/cordles...less-1-2-inch-hammer-drill-driver-kit/2602-22

Oh, no doubt, Milwaukee is the tool to be had. Their portable band saw never dies! I just can't dig that deep into my wallet without waking the moths.
 
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