Length of OAK

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VintageGal

Member
Mar 25, 2022
91
NorCal
Reading pellet stove manuals to understand how each stove manufacturer deals with outside air intake. I read both Enviro and Travis Industries suggest using the ash dump in the firebox for outside air --but Harman never points to the ash dump as a source for outside air; they recommend venting alongside the chimney liner to obtain fresh air on the roof.

I don't know how to begin to explain how frustrated I am with the lack of technical information I am given from stove dealerships. Very frustrating.

Tomorrow I can provide pictures, but tonight I just wanted to ask if there is any difference between obtaining fresh air at ground level versus at the top of the house?? Cold air is cold here but I assume that the air is warmer closer to the ground that it is at a height of 15 or 20 ft?

And for the fresh air intake kits, I'm only seeing them offer 5 ft of venting.

What's the typical length of your fresh air intake liner or hose or I don't know what you call it?

Thanks for details you can provide. I am forced to depend on dealership because anyone outside my County will not install outside of their service area. So the local dealership seldom sees in need for an oak. I think it's much better to have one than not.
 

m159267

Burning Hunk
Mar 12, 2009
215
East-Central MO
My OAK extends 2' parallel to the floor to an outside wall (basement install) - it works great. The outside hood is protected from the elements by an overhead deck. So no fear of snow covering it.
 
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VintageGal

Member
Mar 25, 2022
91
NorCal
My OAK extends 2' parallel to the floor to an outside wall (basement install) - it works great. The outside hood is protected from the elements by an overhead deck. So no fear of snow covering it.
Distance What's the total length of your outside air venting set-up?
 

johneh

Minister of Fire
Dec 19, 2009
4,155
Eastern Ontario
The oak (outside air kit ) can be as long as necessary to get outside air to the stove
My OAK is 6 ft. from the stove to termination outside the building (my shortest run possible)
My friend's Oak is close to 30 ft runs inside the chimney chase to the roof. His stove is in the center of the house mine is on an outside wall. It all depends on your application and where the stove is located
 
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VintageGal

Member
Mar 25, 2022
91
NorCal
The oak (outside air kit ) can be as long as necessary to get outside air to the stove
My OAK is 6 ft. from the stove to termination outside the building (my shortest run possible)
My friend's Oak is close to 30 ft runs inside the chimney chase to the roof. His stove is in the center of the house mine is on an outside wall. It all depends on your application and where the stove is located
Thank you! That's exactly the kind of information I needed! Would you know if there is any benefit to obtaining outside air from the chimney height or lower to the ground?
 

stoveliker

Minister of Fire
Nov 17, 2019
5,167
Long Island NY
My two cents are that

-there may be a limit on the length of the OAK piping; the air is sucked in via a fan, and the longer the pipe the higher its impedance to air flowing, so the less air is coming in (or the harder the fan has to work). So check the manual what they say about this. If nothing, contact the manufacturer, not the dealer.

-high up or low: there is no inherent benefit to either of the two in my view. Check the manual again; in natural draft systems "up" is generally not allowed. In a forced air system as a pellet stove, this may not be an issue. I would, however, not have the air intake very near the air outlet - don't want to suck in exhaust gases back to the stove.

That's my two cents, but I don't have pellet stove experience (other than reading about them because I like to learn).
 
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VintageGal

Member
Mar 25, 2022
91
NorCal
My two cents are that

-there may be a limit on the length of the OAK piping; the air is sucked in via a fan, and the longer the pipe the higher its impedance to air flowing, so the less air is coming in (or the harder the fan has to work). So check the manual what they say about this. If nothing, contact the manufacturer, not the dealer.

-high up or low: there is no inherent benefit to either of the two in my view. Check the manual again; in natural draft systems "up" is generally not allowed. In a forced air system as a pellet stove, this may not be an issue. I would, however, not have the air intake very near the air outlet - don't want to suck in exhaust gases back to the stove.

That's my two cents, but I don't have pellet stove experience (other than reading about them because I like to learn).
Exactly my concern with the air intake at the chimney crown; even though the pellet exhaust may be six or even 12 in higher than the air intake, that is still too close for my comfort given that air conditions change, wind direction etc. I'd prefer to use my fireplace ash dump and use a 5 or 10 ft vent for outside air. In my situation, the dealership almost never installs an OAK.
 

johneh

Minister of Fire
Dec 19, 2009
4,155
Eastern Ontario
-there may be a limit on the length of the OAK piping; the air is sucked in via a fan, and the longer the pipe the higher its impedance to air flowing, so the less air is coming in (or the harder the fan has to work). So check the manual what they say about this. If nothing, contact the manufacturer, not the dealer.
I agree with stoveliker but you also have to remember that the incoming air is reduced
to get the best possible flame and heat output of the pellets. I do not have a Harman but my
stove works best with the intake air reduced by about 75% via a slide plate.
Much like reducing the draft on a wood stove to get a long clean burn.
The difference being a pellet stove uses a combustion fan to pull air throw
the stove and send it up the chimney
 

VintageGal

Member
Mar 25, 2022
91
NorCal
I agree with stoveliker but you also have to remember that the incoming air is reduced
to get the best possible flame and heat output of the pellets. I do not have a Harman but my
stove works best with the intake air reduced by about 75% via a slide plate.
Much like reducing the draft on a wood stove to get a long clean burn.
The difference being a pellet stove uses a combustion fan to pull air throw
the stove and send it up the chimney
Being that I don't know what motor controls the air intake, I can't begin to imagine how to add a damper to an outside air kit 🙃 But thank you! You raised a very important consideration!
 

EbS-P

Minister of Fire
Jan 19, 2019
2,984
SE North Carolina
My two cents are which ever is cheaper/easier. The combustion blower is blower creates a vacuum in the stove. On my parents there is no gasket on the bottom of the door to allow for air wash up the glass. A little exhaust getting sucked in won’t hurt anything. Any smell is on startup from a leaky vent joint before it heats up to get any natural draft.

I wouldn’t over think the OAK. Sure if it’s an easy install. But you said your house want super tight so Chances are it not necessary. It’s a powered venting appliance. You said you had pellet stove before. If it ran fine I bet this one does too.
Any efficiency benefits have been disputed. Sucking cold combustion air that the fire must heat VS room air that’s already been hot. It’s been argued both ways and I see both points.

As far as clean burning. I don’t recall any air restriction adjustment on my parents Quad. It’s just old now. There is a adjustable gate to that sets the amount of kettles that get dropped with each turn of the auger. You set it once when you set up the stove. Might need to re-adjust if you change pellets and they are different sizes or burn different. Basically you set the amount of fuel for the air the stove supplies.

Download the manual and read through it. You don’t need to understand all of it but just enough to keep the installers honest;).
 

VintageGal

Member
Mar 25, 2022
91
NorCal
My two cents are which ever is cheaper/easier. The combustion blower is blower creates a vacuum in the stove. On my parents there is no gasket on the bottom of the door to allow for air wash up the glass. A little exhaust getting sucked in won’t hurt anything. Any smell is on startup from a leaky vent joint before it heats up to get any natural draft.

I wouldn’t over think the OAK. Sure if it’s an easy install. But you said your house want super tight so Chances are it not necessary. It’s a powered venting appliance. You said you had pellet stove before. If it ran fine I bet this one does too.
Any efficiency benefits have been disputed. Sucking cold combustion air that the fire must heat VS room air that’s already been hot. It’s been argued both ways and I see both points.

As far as clean burning. I don’t recall any air restriction adjustment on my parents Quad. It’s just old now. There is a adjustable gate to that sets the amount of kettles that get dropped with each turn of the auger. You set it once when you set up the stove. Might need to re-adjust if you change pellets and they are different sizes or burn different. Basically you set the amount of fuel for the air the stove supplies.

Download the manual and read through it. You don’t need to understand all of it but just enough to keep the installers honest;).
Thank you. When I was debating the type of pellet stove insert I could afford, I read the manuals and the messages here at the board and ended up feeling concerned. My home has single pane windows but I use heavy drapes and I believe they work just as effectively as installing all new windows which I can't afford. My attic is insulated but my basement floor is not. It's just dirt and it slopes. So the floor is cold enough and I would imagine the cold floor air would serve the pellet stove sufficiently. Anyway heat rises and I do have a ceiling fan 😁✌️
 

VintageGal

Member
Mar 25, 2022
91
NorCal
Thank you. When I was debating the type of pellet stove insert I could afford, I read the manuals and the messages here at the board and ended up feeling concerned. My home has single pane windows but I use heavy drapes and I believe they work just as effectively as installing all new windows which I can't afford. My attic is insulated but my basement floor is not. It's just dirt and it slopes. So the floor is cold enough and I would imagine the cold floor air would serve the pellet stove sufficiently. Anyway heat rises and I do have a ceiling fan 😁✌️
I would imagine the cold air intake or air intake in a pellet stove is what accounts for the loss of efficiency?
 

stoveliker

Minister of Fire
Nov 17, 2019
5,167
Long Island NY
Another cent :)

To my understanding, the airflow through a pellet stove is larger than in a wood stove. If this air is sucked into the stove from the room it is in, it needs to be made up by outside air leaking in. There are plenty of leaks from what I read, so the OAK is not needed for "house tightness" reasons.

But, the large amount of cold air one sucks back into the home to make up for the used heated air, will be inefficient. It may even create colder rooms farther away from the stove, or make cold streams of air towards the pellet stove.

So yes, I would see if you can have a stove installed with an OAK.
 

EbS-P

Minister of Fire
Jan 19, 2019
2,984
SE North Carolina
I would imagine the cold air intake or air intake in a pellet stove is what accounts for the loss of efficiency?
Yes. what it blows out has to be sucked in from somewhere.
 

EbS-P

Minister of Fire
Jan 19, 2019
2,984
SE North Carolina
Another cent :)

To my understanding, the airflow through a pellet stove is larger than in a wood stove. If this air is sucked into the stove from the room it is in, it needs to be made up by outside air leaking in. There are plenty of leaks from what I read, so the OAK is not needed for "house tightness" reasons.

But, the large amount of cold air one sucks back into the home to make up for the used heated air, will be inefficient. It may even create colder rooms farther away from the stove, or make cold streams of air towards the pellet stove.

So yes, I would see if you can have a stove installed with an OAK.
It’s probably less than 100cfm on high. And you probably won’t run on high all but the coldest few days. So it’s like a bathroom fan on when it’s running.
 

stoveliker

Minister of Fire
Nov 17, 2019
5,167
Long Island NY
A bathroom fan is a lot of air in my view.

Reverse the picture (with the same quantity of air flow): mount a bathroom fan in your living room wall and have it blow in cold air mid winter. Way too much for me.
 

VintageGal

Member
Mar 25, 2022
91
NorCal
A bathroom fan is a lot of air in my view.

Reverse the picture (with the same quantity of air flow): mount a bathroom fan in your living room wall and have it blow in cold air mid winter. Way too much for me.
What I'm understanding is that a pellet stoves' efficiency has more to do with regulating air intake rather than with combustion which is almost always 100%
 

stoveliker

Minister of Fire
Nov 17, 2019
5,167
Long Island NY
Yes, but what I'm saying is that it pumps a lot of air, which equates to that same lot of air being sucked in from outside. And the colder it is outside, the harder the stove runs, the more cold air it sucks in.

This is the case for all wood stoves, but the flow through a pellet stove is (to my understanding, and seemingly confirmed by the <100 cfm noted above) is way larger than in a wood stove. And even for woodstoves people use OAKs sometimes.
 
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VintageGal

Member
Mar 25, 2022
91
NorCal
Yes, but what I'm saying is that it pumps a lot of air, which equates to that same lot of air being sucked in from outside. And the colder it is outside, the harder the stove runs, the more cold air it sucks in.

This is the case for all wood stoves, but the flow through a pellet stove is (to my understanding, and seemingly confirmed by the <100 cfm noted above) is way larger than in a wood stove. And even for woodstoves people use OAKs sometimes.
Better efficiency also depends on your exhaust system. Wow what a delicate balance. I guess that's how the wood-burning industry is achieving high efficiency, more air intake?
 

VintageGal

Member
Mar 25, 2022
91
NorCal
Since my dealership is not supportive of an Oak, it's hard for me to be convincing either way. They did say that they would install and OAK if I insisted upon it, but I really have no way to measure my BTU heat loss in my home without an accurate measurement

I did tell them that the rear rooms were colder and the main living area and I can imagine the pellet stove sucking more cold air from those spaces. I'm starting to feel like pellet stoves arent meant for certain home applications
 

stoveliker

Minister of Fire
Nov 17, 2019
5,167
Long Island NY
I believe an OAK will not hinder the combustion efficiency of a pellet stove. And given the make-up air argument, it'll only help with home-heating efficiency.

Combustion efficiency (defined as the most complete combustion of the fuel into CO2 and H2O) is best with an excess O2 (oxygen from air) supplied. I don't think the exhaust system matters much in combustion efficiency once a minimum threshold of exhausting is reached.

But this is reasoned from "general knowledge", not from particular expertise in pellet stoves.
 
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VintageGal

Member
Mar 25, 2022
91
NorCal
I believe an OAK will not hinder the combustion efficiency of a pellet stove. And given the make-up air argument, it'll only help with home-heating efficiency.

Combustion efficiency (defined as the most complete combustion of the fuel into CO2 and H2O) is best with an excess O2 (oxygen from air) supplied. I don't think the exhaust system matters much in combustion efficiency once a

But this is reasoned from "general knowledge", not from particular expertise in pellet stoves.
"minimum threshold of exhausting is reached" --which asks for UNobstructed 3-6-8" chimneys and chimney pipe.

Well this makes choosing an affordable pellet stove rather difficult for my fireplace insert application lol.

I put a deposit on a Quadra-Fire classic day but I also told the dealership that I would like to first see if the Harmon p35i would fit. And the primary reason I would choose one over the other, would be that the Harmon would accommodate air intake at the chimney crown and the CB 1200i would not vent into my firebox Ash dump according to their manual.

If I could do this myself I would. But I'm a 62-year-old woman and it's bad enough I wrangle with 40 lb sacks of pellets. I just can't get people to do what they don't want to do not even for the money.
 
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johneh

Minister of Fire
Dec 19, 2009
4,155
Eastern Ontario
The reason I have an OAK is that I will be damed if I will use air that I have paid to heat
and throw it out my chimney. Cold intake air does not make the stove less efficient.
A dirty stove is less efficient. The lack of combustion air makes it inefficient.
Like a smouldering fire in a wood stove does not produce heat a low black-tipped flame in a pellet stove does not produce heat and it makes the stove and glass dirty
 

VintageGal

Member
Mar 25, 2022
91
NorCal
The reason I have an OAK is that I will be damed if I will use air that I have paid to heat
and throw it out my chimney. Cold intake air does not make the stove less efficient.
A dirty stove is less efficient. The lack of combustion air makes it inefficient.
Like a smouldering fire in a wood stove does not produce heat a low black-tipped flame in a pellet stove does not produce heat and it makes the stove and glass dirt

The reason I have an OAK is that I will be damed if I will use air that I have paid to heat
and throw it out my chimney. Cold intake air does not make the stove less efficient.
A dirty stove is less efficient. The lack of combustion air makes it inefficient.
Like a smouldering fire in a wood stove does not produce heat a low black-tipped flame in a pellet stove does not produce heat and it makes the stove and glass dirty
Say it loud! I hear you! I want an OAK too!