Cold air coming through the ducts?

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the trick is to seal all of the duct connections, therefore you have a sealed system where air cannot leak in or out, or it is at least minimized. if you are covering your intakes ( returns) then the furnace could very likely overheat and go off on high limit. if you seal everythying, supply and return, you aren't going to have any air movement through the duct system, unless the fan or heat is on. also the furnace will work more efficenly if it is recirulating air from the living space, to the living space, rather than leaking out or drawing in from the basement or furnace room. does that make sence?
 
I have the same problem and do exactly what you do, cover all the vents with towels and throw rugs etc. Or I jsut close the luvers if they ahve them. IT is amazing howm much cold air comes in from those. It gets suckd in with my woodstove blower and my fan that I use. My furnace is in a colc basement that can only be accessed from outside. and half of my house is simply over crawlspace so that is even colder. I have seriously thought about purchasing one of those small ceramic space heaters and let it run in my basement 24/7 jsut to see if it had any affect
 
woodjack said:
I use my oil, forced air system as a back-up to my wood heat, but the ducts are cold air channels to my living space from the basement/furnance room. I cover the vents with towels, but then they're closed if the heat kicks on. Do any of you guys have this problem - and a solution?
Click to expand...
So much for cold air not going up.
 
Crabbypatty said:
the trick is to seal all of the duct connections, therefore you have a sealed system where air cannot leak in or out, or it is at least minimized. if you are covering your intakes ( returns) then the furnace could very likely overheat and go off on high limit. if you seal everythying, supply and return, you aren't going to have any air movement through the duct system, unless the fan or heat is on. also the furnace will work more efficenly if it is recirulating air from the living space, to the living space, rather than leaking out or drawing in from the basement or furnace room. does that make sence?
Click to expand...

Yes, I understand completely. I think sealing the supply ducts has helped maintain heat in my home. At least, there seems to be less draft from the vents. I don't know for sure yet, and I'll get to work on the return air ducts.

You say: "a sealed system where air cannot leak in or out or it is at least minimized"
It seems to me that plenty of air can enter the loop where the air return enters the motor (at the filter).

I appreciate your advice immensely.
 
Adirondackwoodburner said:
I have the same problem and do exactly what you do, cover all the vents with towels and throw rugs etc. Or I jsut close the luvers if they ahve them. IT is amazing howm much cold air comes in from those. It gets suckd in with my woodstove blower and my fan that I use. My furnace is in a colc basement that can only be accessed from outside. and half of my house is simply over crawlspace so that is even colder. I have seriously thought about purchasing one of those small ceramic space heaters and let it run in my basement 24/7 jsut to see if it had any affect
Click to expand...

Same situation. My furnace room is ice cold and can only be entered from outside. And my house sits on cement tubes creating a large crawl space area under most of my house.

That's funny. As a joke I was going to ask if anyone used an outdoor woodstove dedicated to heating their furnace room - a two stage system. I like your idea and may try putting an electric, oil filled space heater in my furnace room. Aside from helping keep my house warm, I'm concerned about the pipes freezing because the furnace is not kicking on.
 
Rich L said:
So much for cold air not going up.
Click to expand...
Warm air goes up. Cold air fills the void.
 
You say: “a sealed system where air cannot leak in or out or it is at least minimized”
It seems to me that plenty of air can enter the loop where the air return enters the motor (at the filter).
Click to expand...
woodjack, is there anyway you can post a picture of the furnace and filter? there should be a door on your filter acess, but there isn't allways. a properly constructed duct system is a closed loop taking room air (return) and reheating it and sending it back to the room as warm supply air. it takes a lot of energy, gas, oil or otherwise to heat up cold outside air vs. cool inside air. a little bit of infiltration is ok, but i wouldn't want it to come from a dingy crawlspace.
are your pipes insulated? i would hate to see you freeze up your plumbing as well.
 
LLigetfa said:
Rich L said:
So much for cold air not going up.
Click to expand...
Warm air goes up. Cold air fills the void.
Click to expand...
Huh ??????? Do you mean and I quote,"the ducts are cold air channels to my living space from the basement/furnace room." = Void?
 
Rich L said:
LLigetfa said:
Rich L said:
So much for cold air not going up.
Click to expand...
Warm air goes up. Cold air fills the void.
Click to expand...
HUH ???????
Click to expand...
It's really not that complicated. Cold air is heavy, warm air is light. Think of cold air as water, water, everywhere... higher than the roof. Think of warm air as a cork. If the warm air is allowed to rise above the roof, the water takes up the space.
 
Rather than running a elec heater to keep the basement above freezing, have you thought about heat trace cable? if you heat trace the pipes and then insulate them, over the cable, your pipes will be the last thing on your mind. the heat trace cable has a built in thermostat and keeep the pipes above freezing.
 
Crabbypatty said:
You say: “a sealed system where air cannot leak in or out or it is at least minimized”
It seems to me that plenty of air can enter the loop where the air return enters the motor (at the filter).
Click to expand...
woodjack, is there anyway you can post a picture of the furnace and filter? there should be a door on your filter acess, but there isn't allways. a properly constructed duct system is a closed loop taking room air (return) and reheating it and sending it back to the room as warm supply air. it takes a lot of energy, gas, oil or otherwise to heat up cold outside air vs. cool inside air. a little bit of infiltration is ok, but i wouldn't want it to come from a dingy crawlspace.
are your pipes insulated? i would hate to see you freeze up your plumbing as well.
Click to expand...

Crabbypatty said:
Rather than running a elec heater to keep the basement above freezing, have you thought about heat trace cable? if you heat trace the pipes and then insulate them, over the cable, your pipes will be the last thing on your mind. the heat trace cable has a built in thermostat and keeep the pipes above freezing.
Click to expand...

crabbypatty
First, thanks for your advice. It's immensely helpful and appreciated, and I'm getting a much better understanding of my furnace heat system. Yes, I'll post some photos so you can see what's going on.

I worry about my pipes freezing. The pipes are insulated with black foam, but I'm afraid that may not be enough protection in that cold little furnace room that's difficult to insulate properly.
A boiler mechanic once told me that heat tracer cables often cause house fires so I've been reluctant to use them.
Do you have any experience with them?
 
well, in my experience the only reason to insulate your waterlines is if there is no heat source to them at all. If there is, your better off leaving them exposed sicne hte insulation will hinder the heat to them as well. Having said that, if they are not exposed to the heat eliminate all of the drafts that will be exposed to them. my kitchen lines were freezing constantly when I bought my house. Until I crawled under my floor I didnt know why, but let me tell you, once I got in there I could see perfectly why. Basically the pipes were literally 2-3" away from the inside of my stone foundation with no protection. I could see the light of day through the sill plate and that cold draft was hitting them constantly. I plugged the holes. That summer I got an Icenonene spray insulation company to come in and foam my entire inside of the stone foundation to eliminate drafts in the crawl space. what a great thing! I could see holes everywhere in the stone foundation, and I am talking likte 2-5" holes not pinholes. havent had a problem since.
 
Do you have any experience with them?
Click to expand...
I have installed them on condensate pipe in attics and on water pipes in basements, maybe you should put a thermo. down there , preferably one which records max and min temps, and see what it gets down to. You havent froze up yet, so you may be OK. Properly installed, the heat trace is as safe as any other electrical device, in my opinion. They don't get that hot.
 
also, a furnace is only as good as the distribution system, aka ductwork. you could put a 95% effiecnt furnace on a crappy duct system and your effiency goes way down due to leakage and duct loss.
 
This is good stuff.
I am going through this problem right now. My first stove without an OAK and I am kicking myself for not putting it in. I have never had this problem before with the cold coming out the vents. It actually comes out of my cold air return vents.
I was convinced that it is was due to the lack of OAK. Not totally convinced now but probably going to install one in the spring anyways.

I have sealed 50% of my ductwork. Some with shiny silver tape and some with duct mastic. They both work well but I wash down the ducts because they are filthy.
 
d.n.f. , you are right. the stove needs air from somewhere to complete combustion properly, and it's gonna take it from the easiest place it can. so if you provide an OAK, it will take it from there rather than your return ducts.
 
So, if I install an OAK, my house will be warmer? Can an OAK be installed on any woodstove? And what about he concept of feeding frigid air to the woodstove. Does that cool the stove down? Do you burn more wood to maintain stove temps?
 
woodjack said:
So, if I install an OAK, my house will be warmer?
Click to expand...
There will be fewer cold drafts so yes, the house will feel warmer. The stove is already warming the air it consumes so it's six of one, half dozen of the other as far as having to heat the combustion air.
 
LLigetfa said:
Rich L said:
LLigetfa said:
Rich L said:
So much for cold air not going up.
Click to expand...
Warm air goes up. Cold air fills the void.
Click to expand...
HUH ???????
Click to expand...
It's really not that complicated. Cold air is heavy, warm air is light. Think of cold air as water, water, everywhere... higher than the roof. Think of warm air as a cork. If the warm air is allowed to rise above the roof, the water takes up the space.
Click to expand...
So do you mean if the warm air is not allowed to rise above or through the roof the water or cold air won't have any where to go or a space to fill ? So maybe insulating to the point of keeping the warm air from going through the roof is an answer.
 
Rich L said:
LLigetfa said:
Rich L said:
LLigetfa said:
Rich L said:
So much for cold air not going up.
Click to expand...
Warm air goes up. Cold air fills the void.
Click to expand...
HUH ???????
Click to expand...
It's really not that complicated. Cold air is heavy, warm air is light. Think of cold air as water, water, everywhere... higher than the roof. Think of warm air as a cork. If the warm air is allowed to rise above the roof, the water takes up the space.
Click to expand...
So do you mean if the warm air is not allowed to rise above or through the roof the water or cold air won't have any where to go or a space to fill ? So maybe insulating to the point of keeping the warm air from going through the roof is an answer.
Click to expand...
Yes, that is what I'm saying.
 
There is no question that insulating and sealing your envelope is the key to keeping your house warm. However, no matter how well insulated your roof and walls are, if you have a hole or gaps in your floor cold air will rush in - and the warm air will escape through the same hole.
 
woodjack said:
...if you have a hole or gaps in your floor cold air will rush in - and the warm air will escape through the same hole.
Click to expand...
That defies the laws of physics.
 
I'm not looking for an argument - I know we're all here to help each other, BUT . . . if you have a well insulated, air tight home and cut a six inch hole in the floor a rush of cold air will enter. . . and will continue to enter until you cover that hole.

On a more practical level, that is why we want to seal all gaps, even small gaps near the floor in an otherwise tight envelope. More precisely, it's the warm air that's escaping through that hole, but what we feel is the cold air pushing it out. Cold air seeping under doors is a common dilemma everywhere.

I'm not a scientist, but in the words of Bob Dylan ". . . you don't have to be a weatherman to know which way the wind blows".
 
Here are some photos of my furnace and ducts.

As you can see there is a large register in the return duct just before it enters the blower (I think it's the blower). Since there's a register in the duct, aren't the gaps in the duct themselves similar in effect. Will sealing the gaps have any benefit?

How can a system be closed if there are open registers. Don't the registers themselves open the system to outside air?

Regarding the filter, I know, I should figure out a way to attach the filter properly to the duct opening. Can I just put the filter on top of the register?

I bought this house last year and this is my first experience with a forced air system. As always, any suggestions you have would be appreciated.
 

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