Upper floor very hot! Duct work issue?

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Old 12-08-10, 10:40 AM
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Upper floor very hot! Duct work issue?

Hello- I am asking a question in reference to a two floor home that I have. The main floor houses the furnace in a small utility room. Both the lower and upper floor have a separate thermostat to control the furnace. I am having a huge issue keeping the upstairs anything short of scorching hot (78-80 degrees) while the lower level t-stat is set to 68. I am not sure if all of the hot air is rising, or what exactly is occuring- but it is very very hot upstairs.

I have shut off all of the dampners to the upper level, and I am concerned that maybe there is too much hot air that is not going anywhere, that it is just somehow coming off of the furnace and the closed ducts, and rising into the upper level through the non-insulated floor that separates them? Even with closed ducts and vents in the upper level, I can still feel the warm air escaping (although it is drastically reduced in terms of pressure)

I am also not 100% sure on the functionality of the cold air returns. Is it possible that hot air is entering the upper level and not being re-circulated through the cold air returns? Or that I am not drawing sufficient outside air into the furnace to begin with? The furnace is in a very small enclosed closet area.

I think I have ruled out the t-stats as they are both brand new, but something just doesn't seem quite right. Or, will the upper floor be permanently at the mercy of the lower level temp. I am even wondering if it is possible that heat is escaping the lower level quickly, and the t-stat keeps asking the furnace for more hot air, then it goes no-where after it rises to the upper level.

Any troubleshooting thoughts?
 
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Old 12-08-10, 11:14 AM
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What size unit and what size return grills and duct on each floor
 
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Old 12-08-10, 11:35 AM
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I would have to look to get the size of the unit....I am really not sure.

There is a large return grille in the upper floor (probably close to 16 x 16. Maybe bigger- it is in the wall, with the wall cavity servicing as the return duct I think.

I am not 100% if there is even a return on the main floor. I will have to check that too.....

Could you possibly give me some feedback about what you are thinking???
 
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Old 12-08-10, 11:46 AM
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So, if you have two zones, are you ever getting the furnace to pump air into the upper level?
 
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Old 12-08-10, 12:03 PM
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Yes, there are ducts leading to the upper level, and it will indeed blow air up there. But, it is getting so hot up there, that I have shut the dampners in the ducts off, so that no warm air blows in the ductwork leading to the upper unit. Still, the warm air is somehow escaping from the lower level and heating the heck out of the upper level- too much so.

Should I have insulation between the levels? I am just trying to keep more hot air in the lower level instead of escaping so quickly to the upper level and heating it to the point of being intolerable.

Does closing off the ducts to the upper level hurt this plan? How could so much air be getting upstairs? This is why I am wondering if the cold air return ductwork could have something to do with it?
 
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Old 12-08-10, 12:34 PM
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Seems like you have a problem with the thermostat if it's blowing warm air up there when the temperature is above where you have the thermostat set
 
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Old 12-08-10, 12:37 PM
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Well as I mentioned, I have a tstat in both the upper and lower level. I am wondering if somehow there is just too much hot air blowing into the lower level, then escaping quickly to the upper level- all the while the lower level tstat is not sensing that it has warmed up to the desired temperature. Does that seem plasible? Maybe I am sounding silly here....but basically, no matter how low I keep the tstat down stairs, the upstairs is incredibly hot- to the point of needing to open windows. I know warm air rises.....but something is not communicating properly, or recirculating properly, or something....way too much hot air in the upstairs quarters.

Any other thoughts?

Both tstats are brand new.
 
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Old 12-08-10, 03:17 PM
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I don't think we will be able to help u from here!
1 could be a damper motor issue
2 could be a tstat issue
3 could be a return duct issue
4 could be a supply duct issue
Are some of each.
I'd call a good hvac company to help u out. You will have to pay them because there will be a lot to check for not a lot of money in ther pocket.
They will need to start with a manual j and d then they can go from there
 
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Old 01-03-11, 12:49 PM
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Hi, I have a similar problem. I have a 3 story Townhome with Central Air (unit located on first floor). My bedrooms are on the third floor and each bedroom has a supply vent and return grille. When the air is on I can feel cool air coming out of the supply vent but the 3rd floor never gets as cool as the first/second.

However, after much researching, I found out that my townhome does not have a ridge vent (but does have a sizable attic). I think the hot air in the attic is keeping the air on the third floor warmer than on the other floors. (Note my thermostat is on the second floor).
 
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