Outside Air Kit worth it?

[avc8130]

I am in the process of prepping my hearth for my Jotul Oslo I am picking up Saturday. Would an outside air kit be worth installing? My house is a 1980s ranch with some more modern windows and a bit extra insulation in the attic. I am at a crossroads right now where adding the kit would be easiest as I could design it into my hearth whereas if I wanted to add it later it would be more difficult. I am pretty sure my house is NOT too tight to run a stove, so this would be more so cold air isn't drawn in for the combustion.
ac

 

[par0thead151]

the benefit of using inside air is it circulates air in the home. most houses are stuffy in winter.

 

[John_M]

avc, The pros and cons of Outside Air Kits (OAK) have been pretty thoroughly wrung-out in many previous threads. On this site, do a search for OAK and you will get as much info as you can handle. Also check out this very informative link: (broken link removed to http://www.chimneysweeponline.com/hooa.htm)

 

[madison]

Did the freestanding stove that you are replacing burn adequately? If yes, I would personally opt out. And make sure you completely read and understand the clearance specs for the Oslo. Good Luck.

 

[gpcollen1]

the benefit of using inside air is it circulates air in the home. most houses are stuffy in winter.

Huh? Unless you have a very tight/efficient house, you have plenty of air exchange.

Using an OAK ensures you do not burn your already heated indoor air. You make the call...

 

[RRJ22]

I live in an old, drafty house. When I installed my OAK after burning two years without it I immediately noticed that cold air was no longer flowing through the house towards the stove. It feels much more comfortable. Another side benefit is that the air in the house is not drying out as bad as previous years, at least according to the hygrometer on the wall.

 

[Bone1099]

seems to me like the only air circulation provided by a stove without OAK would be that slow steady draft of cold air coming in around windows doors light fixtures etc.
I have read thechimneysweeponline's article which is very informative. The part that surprised me most was stove air consumption. Correct me if im wrong but i believe it said that the average sized wood stove will evacuate all of the air inside a 1500sq ft home every 15 minutes. Thats a bunch of cold air If i were designing a new hearth i would design it in whether you use it now or not the option is aready there. Sure do wish mt fisher insert was rigged up for outside air. Well I guess it is but the air comes from around door and windows.

 

[Hanko]

Sometimes a outside air source is necessary. In the case of my shop, dense pack foam insulation, it was a must. In my home I dont have one, but would probably benifit from it.

 

[avc8130]

Does anyone have pictures or information about the outside air kit for the Jotul Oslo? I searched here and the Jotul sight and can't find much that shows it.
ac

 

[thechimneysweep]

The part that surprised me most was stove air consumption. Correct me if im wrong but i believe it said that the average sized wood stove will evacuate all of the air inside a 1500sq ft home every 15 minutes. Thats a bunch of cold air

Just a couple of corrections:

1) The reference you cite at (broken link removed to http://www.chimneysweeponline.com/hooa.htm) wasn't about an average size wood stove, it was about a fireplace.

2) The house being evacuated by the fireplace every 15 minutes measured 1,000 sq.ft., not 1,500 sq.ft.

Here's the math: a 1,000 sq.ft. house with 8' ceilings contains 8,000 cubic feet of air when totally empty of other objects. An open fireplace with a chimney flow rate of 500 cubic feet per minute would evacuate that much air in 16 minutes (8,000 / 500 = 16). The adjustment to 15 minutes can be explained by the fact that a healthy portion of the space in that house is likely to be occupied by furniture, appliances, cupboards, people and other objects instead of air.

An average size wood stove will only draw something like 15-40 cu.ft./minute, so it would take at least ten times as long (150 minutes) to evacuate the same house. Nonetheless, even this vastly reduced outflow is not insignificant: many people complain about the entry of 8,000 cu.ft. of cold outdoor air into their house every 2-1/2 hours when using their wood stoves, and install OAK's as a remedy.

 

[madison]

tom,

cpl ?'s

do any stove mfg.'s have airtight connections for the OAK's?

and typically are the primary and secondary air's feed from the same place?

 

[JV_Thimble]

avc, The pros and cons of Outside Air Kits (OAK) have been pretty thoroughly wrung-out in many previous threads. On this site, do a search for OAK and you will get as much info as you can handle. Also check out this very informative link: (broken link removed to http://www.chimneysweeponline.com/hooa.htm)

Yes, but it's hard to separate out threads for OAK (as we're discussing) and oak (the wood). Tried searching for 'OAK photos', and I would say it's rather frustrating. Would be great if the search tool here could recognize all caps...

FWIW, my take on this (old, leaky house, getting new chimney and stove) - We'll get our new chimney and stove installed, and consider an OAK if we have problems later. I don't think it will be very hard for us to do this after the fact, if needed.

 

[LLigetfa]

My name isn't Tom, but I can answer part of that. My RSF stove (fireplace) has an airtight connection to the OAK. It uses the OAK for both the primary and secondary combustion air. The zipper air however is fed by indoor air through a 3/8ths inch hole. Whether ir not it's typical, I cannot say.

 

[thechimneysweep]

Hey Madison,

PE's OA intakes are through the pedestal, or through an under-firebox plenum in models with legs. Neither are even close to air-tight. Hearthstone's gasketed OA adapters fit tight, but there are openings to the room through the draft control mechanisms. Avalon used to have a proprietary rectangular setup for thru-floor OA which was gasketed, but air could still flow through the draft control area. There might be some truly airtight outside air systems out there, but I can't remember ever seeing one.

I've seen models where the primary and secondary air both come from the same place, and models that have the secondary air intakes in a totally seperate location.

 

[avc8130]

Does anyone have any details about the Jotul OAK?
ac

 

[madison]

Tom/LLigetfa,

Thanks for the insight.

I've never owned or lived in a "tight" house. And I have a hard time believing that there are not enough leaks in a tightly built house to allow combustion in a oven, fireplace, wood stove etc. And if the next home we live in is a tight home, the last thing I would want to do is punch a hole thru it for a wood stove that does not have "tight" connections to this outside air supply, otherwise this hole could be a "jet stream" of outside air into your home if the area of the penetration gets pressurized from wind.

Am I missing something?

 

[LLigetfa]

Am I missing something?

I think you are. If the wind were to "pressurize" a well sealed house, at some point the pressure would equalize. The house cannot expand so where would the air go? Look at a hot air balloon... well sealed but it has a giant hole in the bottom and the hot air stays inside.

The general reason for the OAK is so that you don't need to provide makeup air that is taken from the room. It's not that the house is so tight that there isn't enough air to burn. It is more a case of having a pressure deficit because makeup air is being blocked from entering the home. Leaky homes often have a greater pressure deficit affecting stove operation more than tight homes.

If makeup air is drawn in through cracks around windows, that can result in frost and condensation issues by the chilling effect. It also creates a certain discomfort to feel a cold draft. People tend to seal up any crack where they feel cold air entering but by so doing, they are creating a larger pressure deficit that can affect the stove operation because of reduced draft.

A home needs makeup air. If air leaks out through cracks, it often goes unnoticed because one doesn't feel a cold draft. The air leaking out also takes moisture with it which can result in condensation issues inside the walls. Sealing up where air leaves is better than sealing up where air enters. If less air leaves, less makeup air has to enter. In reality, you do also want to limit where and how much air can enter but in balance, keeping in mind other sources of air loss.

 

[JV_Thimble]

Does anyone have pictures or information about the outside air kit for the Jotul Oslo? I searched here and the Jotul sight and can't find much that shows it.
ac

This post seems to have some pics - https://www.hearth.com/talk/threads/58712/

 

[madison]

LLigetfa,

Thanks, the hot air balloon illustration really helped with my misconceptions. Much appreciate the time and effort to enlighten us.

 

[avc8130]

Does anyone have pictures or information about the outside air kit for the Jotul Oslo? I searched here and the Jotul sight and can't find much that shows it.
ac

This post seems to have some pics - https://www.hearth.com/talk/threads/58712/

From that thread it looks like the OAK is nothing more than a 4" vent run to the rear/under area of the stove. I figured it would be some contraption that connected directly to the stove to supply the OA only to the stove.
ac

 

[burleymike]

I am very happy I did the OAK. Like previously mentioned it has been much easier to keep the humidity level in the house at 45% in the past I would have to keep a humidifier running 24/7. The big benefit is when we turn on the kitchen range hood we don't start to get smoke in the house. The only drawback is with the Osburn insert the OAK does not directly connect to the stove it dumps the outside air in the air jacket below the stove right below the air intake to the stove. If we don't have a fire burning and the wind comes from the east (where the fireplace is) you can feel the cold air coming in.

 

[madison]

Thanks for the sharing your experience burly. do you stuff it when not burning? can't wait to fish your area soon as the your nonstop storms subside this spring

 

[Needshave]

The only drawback is with the Osburn insert the OAK does not directly connect to the stove it dumps the outside air in the air jacket below the stove right below the air intake to the stove. If we don't have a fire burning and the wind comes from the east (where the fireplace is) you can feel the cold air coming in.

How about a door that can be closed when not in use. Or close it by stuffing a rag in it.

 

[burleymike]

I burn 24/7 in the winter, only time I have noticed the cold air is several hours after the fire dies while I am not home. I probably will not block it off during the summer since running the bathroom or kitchen fans will result in chimney air getting pulled into the the house.