Do Outside Air Connections really affect humidity that much? I've read its a benefit, and while that makes sense to me - not having outside air "suck" moisture out of the air - but does anyone know by how much? I want a PE Summit insert so I can utilize this benefit. My wife wants a Country Legacy C260 for the big window and thinks we will have to get a humidifier anyway so the difference is negligible.
OAK and Humidity
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Since air can hold more moisture when it is warm, we will always experience a loss of humidity when we fire up our stoves. I don't see how a OAK can help with this. I can see how a OAK could stop humidity from condensing around the various cracks as cold air is pulled in, but this really doesn't remove humidity from the environment. I'd call it a non event. I run a humidifier.
Matt
Matt
An OAK would not reduce the loss of humidity enough to not need a humidifier. That said however, I would not want humidified indoor air to be sucked into the stove only to condense in the chimney.
Thanks everyone. Your comments make sense and I'm going to make the OAK a non-factor in our decision. It seemed PE was the only manufacturer that had an outside air option for an insert.
That is interesting - I would have thought the responses would have been along the lines of "it could be one of the biggest factors".
What is really happening is the cold air outside may be at 50% relative humidity. When that air enters the house and warms, it can hold much more moisture so the relative humidity effectively drops - say to 20%. (though the actual moisture in the air is the same) When we talk about the stove 'drying out the air' it's simply because we're pulling in outside air and warming it which causes a drop in the relative humidity.
Based on that, anything you can do to stop pulling in outside air would help. How big of a factor is the OAK? Well that would depend on what the other sources of air infiltration are. If you live in a leaky / drafty old house, it might not make much difference. But if you live in a new / remodeled, well insulated, 'tight' house, the stove could be one of the major sources of outside air exchange, hence one of the major causes of drying the air.
One way of comparison, if you've ever run heat such as electric or heat pump which don't exchange outside air, the OAK would essentially be equivalent to those since it would stop outside air exchange as well. Another ballpark method would be to estimate the amount of wood you intend to burn, then consider stoves roughly use a 20:1 air/fuel ratio. So a cord of oak wood is about 4,000 pounds x 20 = 80,000 pounds of air @ .075 pounds/cubic foot, roughly 1.1 million cubic feet of air pass through the stove to burn that cord of oak wood. A 2000 square foot house with 8' ceilings is 16,000 cubic feet of air. 1.1 million cubic feet of air / 16,000 cubic feet in the house means that cord of wood needs about 66 'houses' worth of air to burn. Burn a cord a month and you are pulling all the air out of the house 2x per day.
What is really happening is the cold air outside may be at 50% relative humidity. When that air enters the house and warms, it can hold much more moisture so the relative humidity effectively drops - say to 20%. (though the actual moisture in the air is the same) When we talk about the stove 'drying out the air' it's simply because we're pulling in outside air and warming it which causes a drop in the relative humidity.
Based on that, anything you can do to stop pulling in outside air would help. How big of a factor is the OAK? Well that would depend on what the other sources of air infiltration are. If you live in a leaky / drafty old house, it might not make much difference. But if you live in a new / remodeled, well insulated, 'tight' house, the stove could be one of the major sources of outside air exchange, hence one of the major causes of drying the air.
One way of comparison, if you've ever run heat such as electric or heat pump which don't exchange outside air, the OAK would essentially be equivalent to those since it would stop outside air exchange as well. Another ballpark method would be to estimate the amount of wood you intend to burn, then consider stoves roughly use a 20:1 air/fuel ratio. So a cord of oak wood is about 4,000 pounds x 20 = 80,000 pounds of air @ .075 pounds/cubic foot, roughly 1.1 million cubic feet of air pass through the stove to burn that cord of oak wood. A 2000 square foot house with 8' ceilings is 16,000 cubic feet of air. 1.1 million cubic feet of air / 16,000 cubic feet in the house means that cord of wood needs about 66 'houses' worth of air to burn. Burn a cord a month and you are pulling all the air out of the house 2x per day.
Cool analysis Corey. You are not only changing 100% of the air 2x per day but you are reheating all of that air to the desired room temp. Also consider that since you can't turn these stoves off that there will be air moving through them year round, a slower rate without a fire but still air movement.
I think that more of these stoves are outside air capable than you think. No stove can be installed in WA without the outside are hooked up and since Lopis are made in WA then I propose that it can be fed outside air.
All said, even with an OAK you will still probably have a dry home in the winter. Winter air is dry and all houses leak some. Most folks don't use a humidifier but use some sort of evaporative device like a kettle on the stove. I don't think the kettles do much and I know our house gets dry. All houses get dry in the winter.
I think that more of these stoves are outside air capable than you think. No stove can be installed in WA without the outside are hooked up and since Lopis are made in WA then I propose that it can be fed outside air.
All said, even with an OAK you will still probably have a dry home in the winter. Winter air is dry and all houses leak some. Most folks don't use a humidifier but use some sort of evaporative device like a kettle on the stove. I don't think the kettles do much and I know our house gets dry. All houses get dry in the winter.
"I think that more of these stoves are outside air capable than you think."
That is interesting. You would think that more manufacturers would cite this as a benefit. To date, the only insert manufacturer that I could find is PE. Regency states the I2400 is "mobile home approved" so I would assume that means it is capable of using outside combustion air.
My home was built in 1969 and is a large ranch. Meaning, it is about 2500 square feet on the main floor, but it has an unfinished basement of about 2500 square feet and a stairway to an unfinished attic with 8' ceilings which is about 1500 square feet. We just had all the windows and slider replaced with Anderson replacements windows. That has made a huge difference in temperature and there isn't much draftiness. However, it isn't air tight as some of the entry doors could be tighter and areas around the heater vents aren't exactly tight - so air can get pulled up through the basement and down from the attic. In fact, I have to stuff a towel or something in front of the attic door as cold air seems to fall down the stairs right into the fireplace room. When we burned our old non-epa insert, I could feel a slight draft along the floor. I'm mostly concerned with humidity though. My wife and I get pretty dry skin in the winter and we have 2 young children with a third on the way. They love it hot too. So I'm trying to balance the humidity factor, ease of use (i.e. I won't have time to deal with the fire as my kids attention comes first), heat and looks.
That is interesting. You would think that more manufacturers would cite this as a benefit. To date, the only insert manufacturer that I could find is PE. Regency states the I2400 is "mobile home approved" so I would assume that means it is capable of using outside combustion air.
My home was built in 1969 and is a large ranch. Meaning, it is about 2500 square feet on the main floor, but it has an unfinished basement of about 2500 square feet and a stairway to an unfinished attic with 8' ceilings which is about 1500 square feet. We just had all the windows and slider replaced with Anderson replacements windows. That has made a huge difference in temperature and there isn't much draftiness. However, it isn't air tight as some of the entry doors could be tighter and areas around the heater vents aren't exactly tight - so air can get pulled up through the basement and down from the attic. In fact, I have to stuff a towel or something in front of the attic door as cold air seems to fall down the stairs right into the fireplace room. When we burned our old non-epa insert, I could feel a slight draft along the floor. I'm mostly concerned with humidity though. My wife and I get pretty dry skin in the winter and we have 2 young children with a third on the way. They love it hot too. So I'm trying to balance the humidity factor, ease of use (i.e. I won't have time to deal with the fire as my kids attention comes first), heat and looks.
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