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Dbarton02 06-18-2010 08:06 AM

Circulation Problem
 
I have an American Standard Freedom 80 forced air furnace (I think). It's been heating up out here in the mid-west, and I've been running the A/C to keep things cool in the house.

I'm noticing that my main floor (home is about 2000 sq. ft total) stays a nice, cool 72 degrees, as per my thermostat settings, but upstairs, there is little to no cool air blowing out of the floor registers.

I've tried shutting dampers here and there in the basement to force more pressure into certain areas of the house, but it doesn't seem to work.
My floor registers on the main floor are wood, and do not have a 'closed' option... they stay open all the time.

Does anyone know what could be causing my lack of air circulation / pressure on the second floor of my house? I popped the cover of my furnace off, and there is a fan installed there, but it isn't running (and I'm not really sure what it's there for in the first place).

Is this just a simple fix of blocking a couple of the main floor registers, or do I need to get into something more labor intensive?

Let me know!

Thanks!!!

(definitely need to cool down over here!)

fabrk8r 06-18-2010 09:17 AM

If the blower in the furnace isn't running that would be the first place to start. That blower is what circulates the conditioned air, unless you have another air handler in your system.

I'm surprised you are able to satisfy the thermostat with no blower.

Dbarton02 06-18-2010 09:26 AM

That's where I am confused. I'm not sure exactly what that is supposed to do, and if there is a switch that can engage that... or how I know if it is broken or not.

I'm about as a rookie as it comes when involving this stuff, so any advice/help would be welcome.

How do I check to see if that blower is broke? Are there switches to turn it on and off (and change speeds?)

fabrk8r 06-18-2010 09:39 AM

First, does the blower run when the blower door compartment cover is installed on the furnace? Most furnaces have a safety switch that turns the blower off when the compartment cover is off.

Make sure the door is installed and set thermostat to "Fan" and see if you have any air coming out of your registers.

If you establish that the blower is operational the next thing to check is that you have a clean (as in less than 4 weeks old) filter in your furnace.

If that checks out okay then come back and we'll see what the next step will be.

Dbarton02 06-18-2010 09:42 AM

I thought I covered that in my original post, but I might not have conveyed that completely... My apologies!

I have air blowing through the registers on the main floor of my home. So the blower would then be functioning (though when I took the cover off, the fan didn't appear to be working).

My problem is the cold air reaching the second floor... (Main floor blows fine, though there isn't enough 'pressure' to blow consistently on the second floor).

Thats what I'm trying to figure out - how I can get it boosted - because it shouldn't be blowing that weak... Is there a speed setting on the blower?

fabrk8r 06-18-2010 09:48 AM

Quote:

Originally Posted by Dbarton02 (Post 458078)
(though when I took the cover off, the fan didn't appear to be working).

This is why I wanted to establish that the blower was functioning.

With that fact established we can move forward. How old is the furnace? Do you know if it is a single stage blower, or does it have multiple stages?

I'm going to assume that since you didn't mention that you have any more than one thermostat in the house, that your system is operating with one zone. If you know that is not the case let me know.

Dbarton02 06-18-2010 09:52 AM

I want to say the furnace is about 10 years old. The house was built in 1999, and I don't know of the previous owners replacing it. I'm not sure if it is a single or multiple stage. We've got one thermostat on the main floor, which makes it difficult to hold temperatures since it stops it as soon as it hits the desired temperature (yet the second floor is about 10 degrees warmer).

So---One thermostat. Unknown if its a single or multiple.

fabrk8r 06-18-2010 10:00 AM

Okay, from the age of the system we'll assume that it's just a single stage blower. If you had a multiple stage blower you would have noticed in the past that when the system is running the air speed coming out of the registers would increase or decrease as the heating or cooling cycle started and stopped.

Have we established if the furnace has a clean filter?

Did you use to have more air flow going to the upper level and just noticed this year that it has decreased? What was the upstairs like during the last heating season as apposed to previous years?

Dbarton02 06-18-2010 10:02 AM

This is the first summer we've been in the house, so we never really knew anything about AC airflow upstairs 'till just now - and I just changed the filter out about a week ago.

fabrk8r 06-18-2010 10:36 AM

With all the information you've given I will hazard a guess that the duct system you have was poorly designed and inadequate for your home.

All I can suggest is double check all the dampers that you can find to make sure that any runs of duct that supply the upper level are not dampered off.

As far as installing an inline booster fan, the cheap ones you find at big box stores labeled "duct booster" are pretty much worthless because of the design of the fan. The only booster that would possibly help is called an inline duct fan, and they are kind of pricey, and i don't think they are the ultimate answer for your dilemma.


One thing I'd like you to do for now is take a thermometer and measure a couple temperatures. We want to establish that your A/C is working as it should.

Measure the temperature of the return air to your furnace. The best place to do this is close to the furnace. If you can get it in the middle of the air stream at the filter it would be great!

Then measure the temperature at a couple of your main floor registers.

We want to see approximately a 15-18 degree temperature difference between the return air going into the furnace and the supply air coming out after the indoor A/C coil (evaporator coil). That will help us determine if the duct design will be the road we want to explore.

fabrk8r 06-18-2010 12:07 PM

One thing to check for also is how many and what size return air grills you have on your second floor. If you have none, or they are too small you will not be able to get enough supply air.

beenthere 06-18-2010 12:27 PM

Have you changed or cleaned your air filter recently.


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