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Discussion Starter #1
I plan on enclosing my furnace and gas water heater in a 10x10 foot room in our basement to conceal them. I was researching ventilation needed for the room, and found that a high and low vent should be installed with the size depending on the BTU's.

However, from what I found louvered doors are not recommended? Can someone please explain. Louvered doors seem like they would be larger than a vent, and satisfy both the high and low ventilation requirements.

Any info on this would be appreciated.

Thanks
 

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The furnace (gas I assume) and water heater exhaust air from the house when they operate, so you need makeup air (vents to the outside). A louvred door doesn't provide makeup air.
 

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Discussion Starter #3
Shazapple - Thanks for your post.

But a high and low vent opening, will take care of this? Where a louvered door will not? I guess my confusion is that a 36 in louvered door would seem to have as much opening as the vents?
 

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Where your getting confused, is that the high and low vent would need to be cut in to an exterior wall, outside air. The louver door your refering to, would be drawing air from the basement itself.

I dont see how the high and low vent setup would work in an underground basement. However, there are many ways to pipe in the needed fresh air for combustion.
 

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Discussion Starter #5
So before building a mechanical room for the HVAC it is just ok sitting in the basement without outside air being pumped in, but once enclosed you need outside air pumped in?

I see mechanical rooms regularly in rehabbed properties that I visit with no such outside vents.

I am not challenging your knowledge, or that you are correct, more or less explaining where my view was coming from.

Thanks for the replies.
 

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So before building a mechanical room for the HVAC it is just ok sitting in the basement without outside air being pumped in, but once enclosed you need outside air pumped in?

I see mechanical rooms regularly in rehabbed properties that I visit with no such outside vents.

I am not challenging your knowledge, or that you are correct, more or less explaining where my view was coming from.

Thanks for the replies.
Every state has different codes, need to check what yours would be.

I never really cared for the idea of using inside air for combustion, even in a large room. If my choice, I would want the equipment in a seperate room with outside air for combustion.
 

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sammy37 said:
I dont see how the high and low vent setup would work in an underground basement. However, there are many ways to pipe in the needed fresh air for combustion.
In my area most basements are underground and we are required a high and a low combustion air pipe. For the high one we pipe it in from the outside and 90 the pipe down so it pours in air from up high. For the low one we do the same thing but then pipe it down to about a foot off the ground. We do all of this in 6" galvanized and have intake hoods on the outside
 

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Discussion Starter #8
Hmm. this unit was installed just 2 years ago, and is in a basement, and passed inspection by the county, but unless I'm missing something there is no intake or outtake.

I will take some pics and post online shortly.
 

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In my area most basements are underground and we are required a high and a low combustion air pipe. For the high one we pipe it in from the outside and 90 the pipe down so it pours in air from up high. For the low one we do the same thing but then pipe it down to about a foot off the ground. We do all of this in 6" galvanized and have intake hoods on the outside
Makes sense. I figured there must be some kind of pipe setup to get it in there.
 

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Hmm. this unit was installed just 2 years ago, and is in a basement, and passed inspection by the county, but unless I'm missing something there is no intake or outtake.

I will take some pics and post online shortly.
There probably isn't, I've never seen vents outside other than the actual pvc intake run outside. But I've seen plenty of units intaking basement air, none of them to my knowledge had vents going outside.

Your unit should work fine without them it's probably just a code thing that doesn't apply in your area. But I would recommend doing something 9like a louvred door) to allow more air into such a small room suuounding your furnace.
 

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if you do not bring in combustion air from the outside it will cause a negative pressure in your house. this negative pressure will pull in from somewhere. if you have a natural draft water heater it will pull in air from that flue. this will make the water heater not vent correctly and it WILL spill out Carbon Monoxide into your house. yes the combustion air is just a code thing but codes are there to protect people and lives. even if you just bring it in from louvered doors it will still cause negative pressure in your house. it is an inexpensive project that is very easily DIYed.
 

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if you do not bring in combustion air from the outside it will cause a negative pressure in your house. this negative pressure will pull in from somewhere. if you have a natural draft water heater it will pull in air from that flue. this will make the water heater not vent correctly and it WILL spill out Carbon Monoxide into your house. yes the combustion air is just a code thing but codes are there to protect people and lives. even if you just bring it in from louvered doors it will still cause negative pressure in your house. it is an inexpensive project that is very easily DIYed.
Yes it will create negative pressure, but it won't create any situation that he doesn't already have existing. And like I said I've worked almost 10 years in service and have seen many 90% furnaces intaking house air, not to mention all the 80% furnaces and I've never seen vent's going outside. None of those people have had any Carbon Monoxide issues and I can't imagine none of them had natural draft water heaters.

And yes codes are there to protect people, but some areas have codes that are a bit excessive. Just because something is against a code in some particular area doesn't make it dangerous.
 

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JScotty said:
Yes it will create negative pressure, but it won't create any situation that he doesn't already have existing. And like I said I've worked almost 10 years in service and have seen many 90% furnaces intaking house air, not to mention all the 80% furnaces and I've never seen vent's going outside. None of those people have had any Carbon Monoxide issues and I can't imagine none of them had natural draft water heaters.

And yes codes are there to protect people, but some areas have codes that are a bit excessive. Just because something is against a code in some particular area doesn't make it dangerous.
That is all true but my main concern is always safety rather than cost. And why does it hurt to spend a small amount of to ensure his families safety and peace of mind. It's true that you don't need to bring air if your house is old and leaky or your windows are not sealed properly. The furnace is currently pulling its combustion air from an unfinished basement which is a very large space to pull air from. Once you close it off in a smaller room. Even with louvered doors the unit is still pulling from a much smaller place. With the air intakes you are pulling air from outside. And the outside is a very large space. Considering everything said I am just telling my view on it all and what I would do from my years ( yes less than 10) of experience.
JScotty I respect you for all that you have said and defending your side of this. And you have given me a lot to think about and consider. I can see you have a lot of experience and truly know what you are talking about.
This whole situation is up to the homeowner all we can do is give advice and how we would do it in our customers houses
 

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I find all this to be hillarious. When I was young my Dad told me that you do not want to make a house too tight. "Why, Dad? arent you just wasting heat otherwise?"

"Well son, you have your pilot lights burning gas, and that uses oxygen, Your Furnace running, which burns a lot of gas, and you have all the chemicals in building materials, and think of your poor mom, what with all the cleaning materials and the stuff they put into the air."

"Yeah, I guess I see what you mean Dad, Thanks"

Fast forward to today. Foam "Stuff" in every crack. Magnetic weatherstripping to steel doors. 10+ inches of insulation in the attic floor, rubber seals on outlets. Poly vapor barriers.

"Sorry sir you have to put in air makeup in your furnace room, or you wont be to code"

What a giant crock of Bovine Scatology :wallbash:
 

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Hey HVAC1000, If he has louvered doors how is he pulling makup air from a smaller area? Hes pulling it from the whole basement through the louvered doors.
 

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That is all true but my main concern is always safety rather than cost. And why does it hurt to spend a small amount of to ensure his families safety and peace of mind. It's true that you don't need to bring air if your house is old and leaky or your windows are not sealed properly. The furnace is currently pulling its combustion air from an unfinished basement which is a very large space to pull air from. Once you close it off in a smaller room. Even with louvered doors the unit is still pulling from a much smaller place. With the air intakes you are pulling air from outside. And the outside is a very large space. Considering everything said I am just telling my view on it all and what I would do from my years ( yes less than 10) of experience.
JScotty I respect you for all that you have said and defending your side of this. And you have given me a lot to think about and consider. I can see you have a lot of experience and truly know what you are talking about.
This whole situation is up to the homeowner all we can do is give advice and how we would do it in our customers houses
Don't get me wrong I'm not saying it's a bad idea to use outside air for combustion. It's just that in my experience it doesn't make a difference. I definately wouldn't go as far as to say it WILL cause carbon monoxide to leak back into your house. I don't think an inducer motor pulls enough pressure to fight the natural draft of a water heater. IMO if it was really something that causes CO to leak into a house it would be against code everywhere.

Like I said I just know I've never seen vents outside, but I've seen a lot of furnaces using indoor air for cumbustion & never had a complaint about carbon monoxide because of it. I do appreciate your experience as well, just sharing what I've noticed, not anything personal to you at all :thumbup:
 

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JScotty said:
Don't get me wrong I'm not saying it's a bad idea to use outside air for combustion. It's just that in my experience it doesn't make a difference. I definately wouldn't go as far as to say it WILL cause carbon monoxide to leak back into your house. I don't think an inducer motor pulls enough pressure to fight the natural draft of a water heater. IMO if it was really something that causes CO to leak into a house it would be against code everywhere.

Like I said I just know I've never seen vents outside, but I've seen a lot of furnaces using indoor air for cumbustion & never had a complaint about carbon monoxide because of it. I do appreciate your experience as well, just sharing what I've noticed, not anything personal to you at all :thumbup:
Ya I guess you are right that saying it WILL was a bit much. It's just that around here the inspectors seem to make a really big deal about it. I think they just try to put any and all liability on the contractors so that's how they make sure.
And thank you JScotty
 

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Ok. I want to put in my 2 cents here. I don't have the HVAC experience that a full time service guy/gal has but I do my share in the property management and rehab side of the business. I live in the midatlantic states and you just don't see vents to the outside in basements for combustion air unless it is a designed powervent system. I manage 40 properties and work in another 50 and they ALL pull air from inside unless it is a powervent system. Putting a room around systems in basements is something I have done dozens of times and I address the combustion air issue by making the room big enough to work in, putting in air vents at the top and bottom of each wall and using louvre doors on the room. We also put lourve doors on the basement door. So where are you pulling combustion air?? You pull it from the whole house! That being said, all of my properties have wired smoke detectors and we put CO detectors in the basement and on each sleeping floor (in our state CO detectors are required on sleeping floors but not in the basement). It is absolutely true that houses are tighter than they used to be, but I haven't seen one yet that doesn't have enough air pull to allow for a safe install, and have never had a detector go off after a basement redesign. So Troyce1 that is my take on it, from someone that has done what you are doing numerous times.
 

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I plan on enclosing my furnace and gas water heater in a 10x10 foot room in our basement to conceal them. I was researching ventilation needed for the room, and found that a high and low vent should be installed with the size depending on the BTU's.

However, from what I found louvered doors are not recommended? Can someone please explain. Louvered doors seem like they would be larger than a vent, and satisfy both the high and low ventilation requirements.

Any info on this would be appreciated.

Thanks
Louvered doors will work fine.

However, now is the time to decide if you want to lower your heating bill or not. If you want to lower it. Then use outside air for combustion. That will reduce the amount of cold dry air you bring into your home. And help keep your humidity up a little.
 

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well what they do in modern houses is they build them super tight, put in high efficiency furnace and water heater so they both get piped in and piped out. then to make up for the high humidity in the house they install what is called ventilation air which is brought in from the outside piped into an air to air heat exchanger that heats it to near room temperature then it is piped into the return air plenum before the filter. then they also pipe out some of the humid air to make up for the air being pulled in. its an odd way to do in "build the house so nothing can get in then bring in some outside air so it doesnt start raining in here".
 
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