basement is always cold- help?

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  #1  
Old 05-21-07, 05:02 PM
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basement is always cold- help?

Hey everyone, I was wondering if anyone could give me some advice
I have been in my new house for about a year and a half, and the basement is finished by the homebuilder. It is 22 feet by 12 feet. There are 2 unfinished rooms off of the finished room, of similar size, maybe a little smaller. one has the furnace +storage space, and the other is mainly for storage. THe basement is always cold, even the finished room. It is especially bad in the summer because the furnace never comes on so its even colder. There is R12 insulation with 6mm vapour barrier around the entire foundation. There are 2 heating vents in the finished room, one in the ceiling and the other at the other end of the room along the floor, and one cold air return in the room, but again in the summer the heat doesnt come on so it makes it even colder. I insulated the interior walls between the finished and unfinished rooms, and it warmed the finished room up a bit, but its still pretty cold. I have no idea why it is so cold in here all the time. I have looked along the foundation and found some gaps which I filled with spray foam, but other than that I don't know what else I can do. I havn't filled along the outer foundation where the siding meets the foundation. Does anyone know what else I can do to warm it up? Its making it uncomforable to be down here now
 
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Old 05-21-07, 05:24 PM
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Wellcome to low bid! Basements will always be a couple degress colder than the main floor because they are in the ground or under it. If it is more than 3 degress off you have a size problem with your HVAC. A heat load will tell you what you need to fix.
 
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Old 06-07-07, 07:33 PM
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Hey, what exactly is a heat load? The size of the HVAC should be okay, because its a brand new house. It is a Amana 92000 BTU high efficiency furnace for a 2900 square foot home including the basement. It is cold down here even in the summer, so the heat can't come on to heat the basement anyway. And I have all the ducts closed off so the cold air from airconditioning doesn't make it colder. I think there is something wrong with the heat set up because I found out the builder didn't tell the heating guys it was going to be a finished basement, or so they say, so what should I have done?
 
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Old 06-07-07, 08:31 PM
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basement is always cold- help?

Do you have proper circulation?

Cold air returns in the basement can reduce the load on the AC and provide a much more uniform and comfortable temperature through the house. I hope you have enough cold air returns in the basement.

Most new high efficiency furnaces have variable speed fans that run very, very efficiently and increase the real efficiency of the AC unit by slowly drawing air over the coils and wringing all the moisture out. Leave your fan set to the "on" position and not the auto position. This way, you get to draw the cold air from the basement and even out the temperature.

When I got a new furnace with a DC variable speed fan, I improved the comfort dramatically (2 degree or less difference from top to bottom with open stairawys) and cut the AC cost using the same compressor and coil.

Dick
 
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Old 06-07-07, 09:01 PM
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The volume of air within a confine remains constant. For example if you blow air into a balloon, the balloon gets bigger and if you let air out of the balloon, it gets smaller. A room or the house for that matter cannot get bigger or smaller as is either brought into or taken out. In other words the volume of heated/cooled air that comes out of your supply vents is equal to the volume of air that goes into your return vents.

Without getting too technical there is a simple test one can do to determine the cause for your discomfort in the basement during the summer. While the air conditioning is on upstairs, take a piece of paper and hold it near the return vent in the basement. If the paper is drawn to the vent, take note of the force in which it is drawn to it. Then take the same piece of paper and do the same thing to a return vent upstairs. Also take note of the force in which the paper is drawn to it. Compare the drawn forces between the basement and upstairs return vents. More than likely the basement return is stronger than your upstairs return. This would account for the discomfort in the basement. Even though you closed the supply vents in the basement, basically what is happening, the basement return vent is drawing cool air that is blowing upstairs to the basement.

What appears to be a simple solution would be to cover the basement return vent with saran wrap or similar plastic. You should see almost an immediate difference in comfort in the basement. However, once you do that you have to check the return vents upstairs again with the piece of paper. The force should be stronger now that you closed off the basement return but there should be no significant increase in noise at the upstairs return vents. If there is, then you have to remove the plastic from the basement return vent and call a HVAC person in to balance you system.

As far as the winter goes in the basement, there can be a variety of reasons for that too.
 
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Old 06-08-07, 11:28 AM
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Heat load needs to be done!
 
  #7  
Old 06-08-07, 01:04 PM
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I would agree with Concretemasonry's suggestion, you have a distribution problem. Each room should have a return (your description wasn't clear to me). Running the fan continously will greatly help control the temperature differences. It works well at my house, I just wish I had a more efficient furnace with a variable blower.
 
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Old 06-10-07, 07:56 PM
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So running the fan at "on" instead of auto should help? Well there is one cold air return duct near the floor on one side of the room. And there are 2 supply ducts, one in the ceiling, above the cold air return (cold air return is on the wall, along the floor) and the other supply duct is on the opposite side of the room, against the wall near the floor. I have 2 unfinished rooms of the finished one. THey are insulated and everything, just no drywall or anything. ANd for some reason the insultation stops a couple feet above the floor, but thats another story. There are 2 supply ducts in one unfinished room (no cold air return) and one supply duct in the second unfinished room ( again no cold air return).
Its not THAT cold in the summer after closing all the supply ducts, but a little uncomfortable so I will try the fan thing. If I set the fan to "on", it won't shut itself off right? I would have to do that manually?
The biggest problem is in the winter. I am not sure what to do. I will have to call in a HVAC guy like you all suggest. Probably the fact I don't have a door in my basement doesn't help either, with all the hot air just rising upstairs, and the cold air falling. Damn basements... lol
 
  #9  
Old 06-11-07, 02:08 PM
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basement is always cold- help?

I do not have a door between my upper and lower levels - it is an open stairacase.

I have three lower supply ducts and two returns. The total areas are about the same. I do not have any dampers, so I control the air flow from the supplys - The returns are always open.

During the summer, I close the lower level supplies and almost close them completely because I have so many supply outlets up stairs. In the winter, I open the lower levels completely and close down some of the uppers and close an interior upper bath comletely becuase of the heat. I have 3 ceiling fans that pay for themselves in terms of comfort.

I use an air filter with a maximum rating of 8 merv to keep the air flowing freely.

Usually if have about a 2 degree difference between upper and lower when the system is running. It can be uncompfortable when Mother Nature rules since I have no control.

The on position of my furnace is very low and maintains a uiform flow unless the the programmed thermostat kicks in in the AM in the winter or during the very hot afternoons. Then it just gets mad and does its job.

Dick
 
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