Installer Said Outside Air Kit Not Necessary?????

If you can look inside the little door can you see the opening going towards the back of the fireplace under the floor of the fire place? Maybe a flashlight and stick a yardstick or tape measure inside the door to see if the opening goes all the way back. If it does you may be able to remove one firebrick and make a steel plate with a 2 inch hole for the fresh air flex pipe to fit into. Maybe it will work depending on how much room you have and where the fresh air attaches to the insert.

What about all furnaces and water heaters? All of these require combustion and emit exhaust and they don't require OAKs. Where is all their makeup air coming from? So I guess if you own one of these units you will need to put an OAK on it too!

ssman said:

What about all furnaces and water heaters? All of these require combustion and emit exhaust and they don't require OAKs. Where is all their makeup air coming from? So I guess if you own one of these units you will need to put an OAK on it too!

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electric water heaters don't use air. some newer furnaces/boilers DO require OAK. those that don't...yeah, they're sucking it in from outside, and thats an inefficiency that is overcome by a pellet burner with an oak.

If you read the instruction manuals and do what it says you probably will live through it regardless if you are sucking hot air from the room for combustion or using outside air. This subject has been beat into the dirt.

cac4 said:

ssman said:

What about all furnaces and water heaters? All of these require combustion and emit exhaust and they don't require OAKs. Where is all their makeup air coming from? So I guess if you own one of these units you will need to put an OAK on it too!

Click to expand...

electric water heaters don't use air. some newer furnaces/boilers DO require OAK. those that don't...yeah, they're sucking it in from outside, and thats an inefficiency that is overcome by a pellet burner with an oak.

Click to expand...

Not electric water heaters, propane or oil. Probably 95% of furnaces don't require an air kit.

I'm trying to weigh the pros and cons here, I don't understand some of the logic regarding "if you don't install an OAK you are just pullling cold air into your house and having to heat it with more pellets".

It seems to me, whether or not you install an OAK, you are pulling the exact same amount of cold air into the house. In one way, the cold air is drawn directly into the stove. In the other way, the cold air is drawn in through cracks in the house.

The same volume of cold air is drawn into the house, whether through cracks or through a hole you cut into the side of the house specifically for that purpose.

If you cut the hole for an OAK, the cold air is drawn directly into the stove, meaning that this cold air is constantly cooling off the stove, and you have to "burn more pellets" to heat the stove.

If you don't install an OAK, the cold air is drawn directly into the room, meaning that the stove will have to burn more pellets to heat the room itself.

If it's zero degrees outside, a huge volume of zero degree air is eiyther drawn into the stove and out the exhaust, to heat that amount of air up takes a lot of pellets. OR the zero degree air is drawn directly into the room and the stove is having to put out more heat to compensate for the air drawn into the room and heating up that air takes a lot of pellets.

I'm having a hard time understanding how one way would burn more pellets than the other. In thinking it through, I think the OAK is more of a requirement to ensure that the stove will burn properly, rather than an efficiency gain, wouldn't a stove manufacturer market it if requiring a OAK would get you more overall heat?

Liter of Cola said:

I'm trying to weigh the pros and cons here, I don't understand some of the logic regarding "if you don't install an OAK you are just pullling cold air into your house and having to heat it with more pellets".

It seems to me, whether or not you install an OAK, you are pulling the exact same amount of cold air into the house. In one way, the cold air is drawn directly into the stove. In the other way, the cold air is drawn in through cracks in the house.

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if pulled directly into the stove, it doesn't mix with the air in your house; it gets heated by the fire, and sent out the exhaust pipe. it doesn't cool the air in your house.

Liter of Cola said:

The same volume of cold air is drawn into the house, whether through cracks or through a hole you cut into the side of the house specifically for that purpose.

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um...no. not at all. air drawn in through cracks in your house cools off the air in the interior of your house. air drawn directly into the stove through an oak does not.

Liter of Cola said:

If you cut the hole for an OAK, the cold air is drawn directly into the stove, meaning that this cold air is constantly cooling off the stove, and you have to "burn more pellets" to heat the stove.

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no again. there isn't any air on this planet that is cold enough to "cool off" a fire. otherwise, we wouldn't need firemen to put out house fires in the winter. If anything, it makes the fire hotter, because colder air is more dense, and contains a higher concentration of oxygen, which feeds the fire even more.

Liter of Cola said:

If you don't install an OAK, the cold air is drawn directly into the room, meaning that the stove will have to burn more pellets to heat the room itself.

Click to expand...

that is correct.

Liter of Cola said:

If it's zero degrees outside, a huge volume of zero degree air is eiyther drawn into the stove and out the exhaust, to heat that amount of air up takes a lot of pellets. OR the zero degree air is drawn directly into the room and the stove is having to put out more heat to compensate for the air drawn into the room and heating up that air takes a lot of pellets.

Click to expand...

we don't really care about the combustion air...not that the exhaust would be at all colder in the cold weather. the fire in the combustion area of the stove heats up metal stuff (plates or tubes) which touch room air on the other side. (that way, you don't get any fumes in the room). fire heats metal...metal heats room air...blower circulates warmed room air. This is called "heat exchange".
I'm sure the computer compensates for the air/fuel mixture, irt colder outside air. if anything, you'll burn less pellets when the air is colder, as that cold air has a higher concentration of oxygen.

Liter of Cola said:

I'm having a hard time understanding how one way would burn more pellets than the other. In thinking it through, I think the OAK is more of a requirement to ensure that the stove will burn properly, rather than an efficiency gain, wouldn't a stove manufacturer market it if requiring a OAK would get you more overall heat?

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well...they do. at least, to some extent. it says in my manual that it'll burn more efficiently with an OAK.

Good answer's cac 4. Ive mentioned these things before on a thread about O>A>Kits in this forum before. Ive discussed this in more depth on the earlier thread. (Do I need an outside air kit installed) Another plus of an OAK is if you are humidifying your house during the
heating season then an OAK is a no brain-er.

Giovanni said:

mralias said:

Ohhhh my brain hurts......What type of Outside Air Pipe should be used? Please don't tell me the same expensive stuff as the vent pipe. Hope there is a cheaper alternative. Thanks. The owners manual does not tell you anything about the type of pipe to use.

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Home Depot sells an inexpensive 3" flexible aluminum duct that fits right over the intake flange and clamped.

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Yeah HD does sell a kit, I tried that and returned it its really crappy like a very streached out spring with Mylar over it ( at least 3 years ago it was) I got mine from the local dealer who told me they buy it from the local Muffler repair shop. Its a very heavy grade flexible (I think its 4"? maybe 3") pipe it fits very snugly over my intake pipe and a clamp isnt needed. I cut the exact same size hole through my wall, caulked around it and put the hood ( also from my dealer) over the end - I think total cost was about $20-$25

FredJ said:

Giovanni said:

mralias said:

Ohhhh my brain hurts......What type of Outside Air Pipe should be used? Please don't tell me the same expensive stuff as the vent pipe. Hope there is a cheaper alternative. Thanks. The owners manual does not tell you anything about the type of pipe to use.

Click to expand...

Home Depot sells an inexpensive 3" flexible aluminum duct that fits right over the intake flange and clamped.

Click to expand...

Yeah HD does sell a kit, I tried that and returned it its really crappy like a very streached out spring with Mylar over it ( at least 3 years ago it was) I got mine from the local dealer who told me they buy it from the local Muffler repair shop. Its a very heavy grade flexible (I think its 4"? maybe 3") pipe it fits very snugly over my intake pipe and a clamp isnt needed. I cut the exact same size hole through my wall, caulked around it and put the hood ( also from my dealer) over the end - I think total cost was about $20-$25

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Nope, you bought the wrong stuff at HD. Yeah, It is crappy stuff .
I`m talking the 3" aluminum springy stuff (no mylar) Not really heavy grade though but adequate.
Sounds like you got something even better though and priced right.

Just when I had it all figured out.....I measured the OAK vent on the stove and the CB1200i Quad has a 2" vent pipe. Anyone know where I can find 2" flex pipe at a 20' length?

two inch flex exhaust tubing will work just fine and is available at just about any automotive store.

mralias said:

Just when I had it all figured out.....I measured the OAK vent on the stove and the CB1200i Quad has a 2" vent pipe. Anyone know where I can find 2" flex pipe at a 20' length?

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At 20 ft long you might want to consider 3" My Harman instructions read that over 15 ft the diameter should be increased to 3" Making it fit shouldn`t be difficult if you can`t find a reducer. You could snip the end a fraction of an inch deep and spaced 1/2 inch apart and bend the tabs in to fit the stove collar snugly.
Silicone the tab joints to make it air tight . Let cure and slide back onto stove. Presto! It`s done.

I highly recommend rigid pipe rather than flex, much less pressure loss and it has less problems with moisture gathering in the pipe.

I find the fresh air requirements for breathing to be met just by the normal everyday movement of people and pets going out the door on the daily basis. The 2 adults and 2 teen plus one dog that needs to go out 4 times a day certainly brings in enough fresh air for us to stay alive

rcredsox said:

In my masonry fireplace (located on an outside wall), I have a small door in the front of the firebrick floor that when open, provides outside air from a channel underneath the fireplace that is vented (with a screen) to the outside of my chimney.

I have a Mt Vernon AE insert pellet stove on order. If the stove sits on the firebrick floor it will probably cover up this opening. Can anyone think of a way I can reuse this outside air connection for my pellet stove?

Here is a picture of the small door location.

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I think your photo is actually an ash dump. My fireplace has an ash dump on the floor in the back and an outside air intake on the left side. However, we added on to the house a couple years ago and blocked the outside air inlet for the side air intake. I'm going to run an OAK through the ash dump though and cobble up a sealed cover with a hole in it for the outside ash dump door. If your ash dump is in the front of your fireplace, I'm not sure how you could get a hose in it. If your hearth is big enough you could buy a freestanding unit instead of an insert and then it would be uncovered. Maybe if your unit has long adjustable legs and there is a zero clearance kit available and your fireplace opening is tall enough you could raise the unit a couple of inches and then work the outside air underneath and through the hole? It's probably easier just to run a longer hose out through the chimney.

-steve

Found what I was looking for. This site has the Z flex 2" pipe kit that is made for the fresh air vent. Cost me $62 with shipping from TX for 25' kit. If anyone is looking for a fresh air kt for the CB1200i Quad and want to run it up the chimney this is the place to get it. Even the place I bought the Quad from said they could not find 2" flex for venting and Quadrafire did not sell it.

Linky poo

You have to call them by phone for the 2" as it is not on their website yet as it is pretty new by Z-Flex. Don't call Z-flex for this as you have to go through one of their dealers.

ssman said:

What about all furnaces and water heaters? All of these require combustion and emit exhaust and they don't require OAKs. Where is all their makeup air coming from? So I guess if you own one of these units you will need to put an OAK on it too!

Click to expand...

You should. High-efficiency appliances require or at least offer the ability to use outdoor air.

Sealed combustion is the best way to go.

Liter of Cola said:

If you cut the hole for an OAK, the cold air is drawn directly into the stove, meaning that this cold air is constantly cooling off the stove, and you have to "burn more pellets" to heat the stove.

Click to expand...

The inefficiency in a stove is not in the combustion, itself. Combustion air that is 20 degrees colder does not mean a flame that is 20 degrees colder. You could put a larger and larger heat exchanger on a given system, and cool the exhaust more (combustion efficiency is the difference between the flame temp and the exhaust temp). However, if you did that, there would be problems of draft and corrosion and soot, because the exhaust was too cool.

The amount of energy the system will waste is fixed by that, regardless of the amount of energy that it consumes in combustion. Colder air means it needs to consume more energy to pre-heat that air, but that extra energy is captured by the system in order to cool the flue gas just enough, but not too much. The energy has to go somewhere - into your house. Colder air (as long as it is not so cold that it interferes with proper combustion) will actually increase efficiency. It sounds counter-intuitive, but the thermodynamics do work out.

If your house is tight enough that it needs additional fresh air, replace a bathroom vent with a HRV, and install a ventilation controller to turn it on as needed.

Joe

Webmaster said:

I think some of them are giving you wood stove wisdom...for a pellet stove. They are not the same......pellet stove used forced draft (electric combustion blower), and an incredible amount of air is used....as compared to a wood stove.

The stove will need air. If you keep the house fairly loose (in and outside a lot, let the dog out, crack windows), then you will have enough air - but, if the house is kept fairly tight, the stove can depressurize the house, causing potential problems.

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What problems would be caused by a stove causing a house to depressuriz, and what are the symptoms of a depressurized house?

BrownianHeatingTech said:

ssman said:

What about all furnaces and water heaters? All of these require combustion and emit exhaust and they don't require OAKs. Where is all their makeup air coming from? So I guess if you own one of these units you will need to put an OAK on it too!

Click to expand...

You should. High-efficiency appliances require or at least offer the ability to use outdoor air.

Sealed combustion is the best way to go.

Liter of Cola said:

If you cut the hole for an OAK, the cold air is drawn directly into the stove, meaning that this cold air is constantly cooling off the stove, and you have to "burn more pellets" to heat the stove.

Click to expand...

The inefficiency in a stove is not in the combustion, itself. Combustion air that is 20 degrees colder does not mean a flame that is 20 degrees colder. You could put a larger and larger heat exchanger on a given system, and cool the exhaust more (combustion efficiency is the difference between the flame temp and the exhaust temp). However, if you did that, there would be problems of draft and corrosion and soot, because the exhaust was too cool.

The amount of energy the system will waste is fixed by that, regardless of the amount of energy that it consumes in combustion. Colder air means it needs to consume more energy to pre-heat that air, but that extra energy is captured by the system in order to cool the flue gas just enough, but not too much. The energy has to go somewhere - into your house. Colder air (as long as it is not so cold that it interferes with proper combustion) will actually increase efficiency. It sounds counter-intuitive, but the thermodynamics do work out.

If your house is tight enough that it needs additional fresh air, replace a bathroom vent with a HRV, and install a ventilation controller to turn it on as needed.

Joe

Click to expand...

Thanks guys. Appreciate the replies and info. I wasn't trying to make the case that colder air = colder flame, I was pointing out that cold air (say 10 degrees) constantly drawn into the back of the stove, through the fan, and forced into the burn chamber does "cool" the stove itself more than drawing in 60 degree air from the house, whether or not that's a significant loss, I still can't determine.

Liter of Cola said:

Thanks guys. Appreciate the replies and info. I wasn't trying to make the case that colder air = colder flame, I was pointing out that cold air (say 10 degrees) constantly drawn into the back of the stove, through the fan, and forced into the burn chamber does "cool" the stove itself more than drawing in 60 degree air from the house, whether or not that's a significant loss, I still can't determine.

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It's not a net loss. It's a net gain. I know it sounds counter-intuitive, but it isn't. The colder air allows for more efficient combustion, essentially.

"Cooling the stove" is not relevant, because it increases the efficiency of the stove to match.

Glowball Worming Bust said:

if a furnace is tuned to a certain air intake volume so to be efficient, wouldnt cooling the combustion air bring more air [due to increased density of cold air] & airwash the heat up the chimney?

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If you don't bother to keep your appliance adjusted correctly, you will get increased mass air flow. That will increase the excess air, and also make the flame burn hotter, which will counteract that effect (presuming we're talking real-world temperature changes, not some hypothetical -100 degree winter). Keeping your air/fuel ratio adjusted correctly will work better, but is not strictly necessary.

Joe

BrownianHeatingTech said:

ssman said:

What about all furnaces and water heaters? All of these require combustion and emit exhaust and they don't require OAKs. Where is all their makeup air coming from? So I guess if you own one of these units you will need to put an OAK on it too!

Click to expand...

You should. High-efficiency appliances require or at least offer the ability to use outdoor air.

Sealed combustion is the best way to go.

Liter of Cola said:

If you cut the hole for an OAK, the cold air is drawn directly into the stove, meaning that this cold air is constantly cooling off the stove, and you have to "burn more pellets" to heat the stove.

Click to expand...

The inefficiency in a stove is not in the combustion, itself. Combustion air that is 20 degrees colder does not mean a flame that is 20 degrees colder. You could put a larger and larger heat exchanger on a given system, and cool the exhaust more (combustion efficiency is the difference between the flame temp and the exhaust temp). However, if you did that, there would be problems of draft and corrosion and soot, because the exhaust was too cool.

The amount of energy the system will waste is fixed by that, regardless of the amount of energy that it consumes in combustion. Colder air means it needs to consume more energy to pre-heat that air, but that extra energy is captured by the system in order to cool the flue gas just enough, but not too much. The energy has to go somewhere - into your house. Colder air (as long as it is not so cold that it interferes with proper combustion) will actually increase efficiency. It sounds counter-intuitive, but the thermodynamics do work out.

If your house is tight enough that it needs additional fresh air, replace a bathroom vent with a HRV, and install a ventilation controller to turn it on as needed.

Joe

Click to expand...

Would cold dry air have more oxygen per cubic foot than warm humid air. If so how would that effect combustion.

Glowball Worming Bust said:

my nonOAK pellet burner intakes a more constant temp air intake from indoor temps than from outdoor temp variations. so does my oil furnace in cellar.

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The air temp fluctuation is not a big deal.

Glowball Worming Bust said:

point is= look at my ventilation link below. indoor air pollution?

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Ventilation is important, but most houses breath enough due to wind and such. If they won't breathe due to wind, then they are very tight, and using an exhaust fan (of any sort) to try and force them to breathe just creates negative pressure in the house. Improper draft due to such things is one of the leading causes of combustion problems with appliances.

If you want ventilation, install a HRV with a ventilation control. It will bring in fresh air, without wasting the heat (they are pretty efficient at transferring the heat to the incoming air) or creating negative pressure.

Joe

slls said:

Would cold dry air have more oxygen per cubic foot than warm humid air. If so how would that effect combustion.

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Yes, but the difference is not huge. Is a system is set properly, the slight excess will hardly be noticeable. The effects of restricted combustion air will be far greater (and less predictable, since the effect of a clothes dryer or such is temporary, not a gradual, seasonal change).

Joe

I have the answer! Use the pipe-in-a-pipe Direct Vent by Selkirk, below is a link to some info although I have no relation to the vendor (web search). Basically draws fresh air through the outer ring and exhausts through the inner pipe. One hole through the wall, incoming fresh air is preheated by the outgoing exhaust. My stove is located in my basement, I know that if I disconnect the OA and fire up the NG dryer, water heater, and furnace at the same time I can see a difference in the flame by opening and closing a window that I do not see with OA hooked up. That convinced me.