To OAK Or Not to OAK

[New Hampshire Jim]

Hi Gang: I just pulled the trigger and Installed a new Harman Advance pellet stove. Here is my question to the Best and Brightest of the pellet burning community.Do I or Do I not add a OAK to my stove.The people I bought to stove from say I do not need one as I am venting into a outside cement block and tile lined chimney.The 3 in pipe comes out of the stove into a TEE up 2 ft. to a 45 Deg. then another foot to a 90 deg. and into the chimney. I had It inspected and the Fire chief said all is well and Harman does not need one.I am replacing and old smoking dragon( 35 year old Jotul). With the wood stove If i lit a fire I would sometimes have to open a outside door to get a draft going and if i put a couple of hard wood logs in I would have to keep a window cracked open or the fire would go out. I could burn soft wood forever.I am thinking the house is real tight. I have searched and searched and found some say add it and others say wait and see how it burns. I would rather add It now than have to do It when the temp is 20 deg. I need your help Please
Jim

 

[imacman]

Jim, as you probably found out by doing a search of OAK in this forum, there are MANY differing opinions on this.

MY opinion is that it can only help. Remember, a pellet stove uses a powered combustion fan that causes a negative pressure inside the house envelope if you don't have an OAK attached.

My rationale is that, if your house isn't tight, why pull cold outside air through the cracks and crevices to feed the stove, which results in cooling the house that your trying to keep warm?

And if the house IS tight, then you don't want to be using air you just spent $ heating to be used for burning and going up the exhaust.

Hope I made sense..........

 

[mnkywrnch]

Jim, as you probably found out by doing a search of OAK in this forum, there are MANY differing opinions on this.

MY opinion is that it can only help. Remember, a pellet stove uses a powered combustion fan that causes a negative pressure inside the house envelope if you don't have an OAK attached.

My rationale is that, if your house isn't tight, why pull cold outside air through the cracks and crevices to feed the stove, which results in cooling the house that your trying to keep warm?

And if the house IS tight, then you don't want to be using air you just spent $ heating to be used for burning and going up the exhaust.

Hope I made sense..........

I 2nd that,well put macman.

 

[MCPO]

sounds like house is real tight & the neg. pressure produced by no OAK may be beneficial , epa recommends 1/3 air exchange/hr. for residential breathing air. if u have oil burner which will not be running as much after pstove install remember that the oil gun is also a source of negative pressure which will no longer act as a housevent. it may be the house is so tight that pstove will need an OAK to provide adequate combustion air & flame + cracked window scenario tells the story.
i'd run without OAK at first.

I`m a big fan of the OAK but the above post has merit or at least deserves some thought. That is for those who have leaky /drafty houses but the OP appears to have a real tight house that seemingly that would definitely beg for an outside air Kit install.
I think it`s rather obviously since his old wood stove fire occasionally went out for a lack of oxygen and he needed a window cracked.
That said I find it hard to imagine a house being that tight but hey! We learn something every day.

 

[tinkabranc]

As the others have mentioned the OAK question comes up frequently here.
IMO I would try it without the oak first as you can always add it later if you still
notice draft issues.

 

[rona]

There is two different things to consider.
One is you couldn't start a wood fire without opening a window. That is enough reason to install the outside air system. The second is why do you want to waste the air you heated by blowing it outside? Seems one of the reasons for installing a pellet stove is to save money. It seems simple logic to believe that if you blow heated air out of a house fresh cold air has to come in to replace it causing drafts etc.
If you follow the examples of the modern gas or oil furnaces most of them use outside air for efficient operation. There has to be a good reason for them to do that.
If you live in a old house with lots of air leaks etc it won't be noticeable but sounds as though you have a solid tight house being you have difficulties starting a fire and have to open a window to get enough air.

 

[New Hampshire Jim]

Thank you all for the replies.As it stands now I will try the stove when It gets a little colder and see how It Is. I am still leaning to the OAK but I dont want to put a hole in the house If its not needed. I think I might try the open window trick while It Is cool
Again thanks
Jim

 

[Xena]

I agree with Macman. One thing I'd like to point out is
that without an OAK I noticed an unwanted draft at
floor level. This was caused obviously by the stove pulling
air in from the room instead of from outdoors.

It was a strong enough air flow to make my feet feel cold
in a room that was 75 degrees. Added the OAK and
the floor level draft was gone and no more cold feet.

If the stove were in the basement or say in another room
that I didn't use, then I may not have even noticed the
floor level draft but where it's in my living room I had
to install an OAK to make things more comfy.

 

[New Hampshire Jim]

Thanks Zeta You gave me food for thought. As I am Maturing one of the things I have noticed Is my feet seem to be colder than when I was a teenager or 20,30,40,50 you get the picture. If the stove will make a floor level draft I will add the OAk
Thanks
Jim

 

[New Hampshire Jim]

Did some fast figuring Harman blower is rated at 140 c.f.m.x60 min = 8100 C.F. Hour
My house Is 1400 Sq.Feet x8 foot ceilings=11,200 cubic feet
At this rate I will be taking all the air in the house that I have spent $$$ to heat with Oil Pellets or Irish hot air and every hour and a half sending it up the chimney.
Are my figures correct If so I would think an OAK is a no brainer

 

[New Hampshire Jim]

I wanted to post a picture of my Install and I just figured out how to do It
Here It Is
Jim

 

[Dougsey]

Hi Jim, Your vent looks to be close enough to the window that an OAK would be a requirement.

That has got to be the largest wall thimble I have ever seen.

 

[New Hampshire Jim]

The stove is venting into an cement block chimney that I vented my wood burning stove into
Jim

 

[imacman]

Did some fast figuring Harman blower is rated at 140 c.f.m.x60 min = 8100 C.F. Hour
My house Is 1400 Sq.Feet x8 foot ceilings=11,200 cubic feet
At this rate I will be taking all the air in the house that I have spent $$$ to heat with Oil Pellets or Irish hot air and every hour and a half sending it up the chimney.
Are my figures correct If so I would think an OAK is a no brainer

Like I said above, and will say again, an OAK makes a lot of sense, regardless of whether or not your house is "tight" or not....and now you know why I feel that way.....I wouldn't want to be sending my already heated air out of the house 16x a day.

Bottom line: put the OAK in....it can't hurt, but CAN help!

 

[New Hampshire Jim]

Thanks Macman Will do
Jim

 

[Delta-T]

that 140 cfm blower is for the distribution blower, not combustion, and the distribution blower is variable speed so 140 is the max. I'm not sure what the cfm rating on the combustion side is...likely closer to 40-50 cfm. i thinks

 

[imacman]

.........I'm not sure what the cfm rating on the combustion side is...likely closer to 40-50 cfm. i thinks

OK, let's be VERY conservative here...at 40 CFM, he still will be replacing the heated air in the house about 4-5 times a day....still not acceptable, IMO.

 

[New Hampshire Jim]

You are so right Macman. Over the years I spent BIG BUCKS replacing windows and doors amd adding 12 in insulation to the roof and 6in to the floors to keep the heat in. My soul purpose of adding a pellet stove is comfort and reduce the amount of $$$ I send overseas

 

[mnkywrnch]

You are so right Macman. Over the years I spent BIG BUCKS replacing windows and doors amd adding 12 in insulation to the roof and 6in to the floors to keep the heat in. My soul purpose of adding a pellet stove is comfort and reduce the amount of $$$ I send overseas

Wise move Jim youwont be dissapointed.BTWthe stove looks real good congrats.

 

[New Hampshire Jim]

Installed and Done Thanks for all the advice
Jim

 

[imacman]

Good move, Jim. Congrats on finishing the install, and don't forget to cover the OAK so bugs, wasps, etc don't get in over the summer. Same thing with your exhaust outlet. And put a note to yourself somewhere to remember to uncover them before starting the stove when it gets cold.