AC not blowing strong enough! Options?

[loybond]

I turned on the AC yesterday in our house, which is about 2500 sq. ft. (plus finished basement) and 5 years old. There's a Goodman AC outside, and the home inspector said it's all good when he did his scam inspection (I hate that guy). Anyways, so yesterday, it was hot outside, and as you all know, we have pretty high UV, so it started heating up inside, and a lot of that heat rose, and upstairs was just sweltering. I set it to 65 and cool, and heard the AC turn on.... and cold air was coming out of the vents. This went on for hours and hours, but upstairs never cooled down. The amount of air flowing through just doesn't seem to be enough. What can I do?

[GTT1]

First off, have you got any cold air return registers upstairs? Preferably in each room and near the ceiling. If so are they working? Take some toilet paper and with the ac fan on the toilet paper should suck against and attach to the grill. The cold air registers play an important part in heating and cooling.

In my previous house I found that it took several days before the upstairs got to its cool point early in the season. I also shut down most of the lower floor registers to allow most of the cool air to be pushed upstairs as it will migrate down to the lower levels.

[woof]

I also shut down most of the lower floor registers to allow most of the cool air to be pushed upstairs as it will migrate down to the lower levels.

+1
Because of the height it's very hard for a furnace to force air up to the 2nd floor and consequently the air flow coming out of the registers there can be significantly less than those on the main floor. I addition, to make things worse the heat buildup in the attic will tend to make the upper level naturally warmer than lower levels in the house.

I found that by closing off all exhaust outlets in the basement and reducing (or closing some of) the main level outlet openings would pressurize the system a bit more and allow more cold air to be forced upstairs.

[loybond]

I've got air returns upstairs, one in the hallway, and one in one of the bedrooms. The very large master bedroom has two vents, but no air return that I can find. You say "cold" air return, is there a distinction from warm?

I don't think the air returns are sucking hard enough to hold the toilet paper there. That's a good idea about the lower floors... I'll give that a shot, but surely, they would have calculated the amount of cooling needed to cool the whole house? The planning for HVAC can't be that bad... or can it?

First off, have you got any cold air return registers upstairs? Preferably in each room and near the ceiling. If so are they working? Take some toilet paper and with the ac fan on the toilet paper should suck against and attach to the grill. The cold air registers play an important part in heating and cooling.

In my previous house I found that it took several days before the upstairs got to its cool point early in the season. I also shut down most of the lower floor registers to allow most of the cool air to be pushed upstairs as it will migrate down to the lower levels.

I see what you're saying... but I would have thought that somehow they would have designed around those limitations. My house just *didn't* cool down upstairs, it was blazingly hot! I've got people in the basement, so I can't shut those vents, though I can try shutting some of the main floor vents. I recently did a bit of demo'ing, so there may be bits of tile/mortar in the vents and returns, could this be affecting the performance?

+1
Because of the height it's very hard for a furnace to force air up to the 2nd floor and consequently the air flow coming out of the registers there can be significantly less than those on the main floor. I addition, to make things worse the heat buildup in the attic will tend to make the upper level naturally warmer than lower levels in the house.

I found that by closing off all exhaust outlets in the basement and reducing (or closing some of) the main level outlet openings would pressurize the system a bit more and allow more cold air to be forced upstairs.

[Pete_Coach]

Just like balancing the ducts for the heating season, they must also be balanced for the cooling season. It will always take some time for the balance to be reached. After every adjustment of the dampers, you need to wait 24 to 72 hours to see if the air is redirected sufficiently.
Also, cold air is heavier than warm air and the furnace fan has to work harder to get the air into the places you want it. If you have a dual speed fan, then you need to set it to the highest level.

[woof]

... but surely, they would have calculated the amount of cooling needed to cool the whole house? The planning for HVAC can't be that bad... or can it?


The ducting systems (locations of ducts, size, etc.) in Canadian homes are typically specifically designed to support the heating system. Air conditioning is simply tacked on to that system almost as an afterthought. You can't do anything about the size or location of the ducts now, all you can do is adjust the duct openings throughout the house to try and move more cold air to where you want it.

[loybond]

By balancing, you mean opening some vents, and closing others, correct? Sorry to be so noobish, but do you know how I can find if I have a dual speed fan and where to find the switch?

Just like balancing the ducts for the heating season, they must also be balanced for the cooling season. It will always take some time for the balance to be reached. After every adjustment of the dampers, you need to wait 24 to 72 hours to see if the air is redirected sufficiently.
Also, cold air is heavier than warm air and the furnace fan has to work harder to get the air into the places you want it. If you have a dual speed fan, then you need to set it to the highest level.

That sucks.

The ducting systems (locations of ducts, size, etc.) in Canadian homes are typically specifically designed to support the heating system. Air conditioning is simply tacked on to that system almost as an afterthought. You can't do anything about the size or location of the ducts now, all you can do is adjust the duct openings throughout the house to try and move more cold air to where you want it.

[Wallly]

Did you check the air filter? , could need changing .
You could try opening a couple of upstairs windows for an hour to dump some heat out.If its humid it takes awhile to bring down the humidity in the air to make it feel comfortable.

[s1301950]

Or simply get a new furnace. After my furnace broke two winters ago, i had to buy a new one to replace it. The newer more energy-efficient furnace are dual (or variable) stage, meaning it works extra hard when the temperature gradient is high and then throttle down a notch when the house is close to hitting the target temperature. Also the DC motor helps in pushing the air around the house. We could really feel the difference in the air pressure for the new furnace.

Filter is also definitely the first thing to check because it is the easiest to change and have the greatest yield in result (stronger air output).

[loybond]

Isn't the filter for the furnace? Does it come into use when using the AC? I suppose I should do that if it does make a difference. The house and furnace are only 5 years old, so I don't think it needs changing.

Where is the temperature sensor located - is it in the thermostat? If that's the case, can I move the thermostat upstairs somehow?

[Pete_Coach]

By balancing, you mean opening some vents, and closing others, correct? Sorry to be so noobish, but do you know how I can find if I have a dual speed fan and where to find the switch?


Well, you probably don't have a dual speed if you don't hear it now.
Do you have access to your ducts in the basement? If so, on those ducts lines there will be a little lever, it is the damper. If the lever is in line with the duct, it is fully open and the air flows to all the room vents on that line. If you move that lever 90 degrees, you close it off (sort of, there is always leakage).
Anyway, you move those levers to the closed position on the basement lines, 1/2 way closed on the mid floor lines and fully open on the top floor (or back rooms). Here is a picture ( I realize the title is for electric forced air but the principal of the ducts is the same).
http://www.oee.nrcan.gc.ca/publications/infosource/pub/home/Heating_With_Electricity_Chapter2.cfm?attr=4
Search for duct balancing on Google for more info.
Isn't the filter for the furnace? Does it come into use when using the AC? I suppose I should do that if it does make a difference. The house and furnace are only 5 years old, so I don't think it needs changing.
Where is the temperature sensor located - is it in the thermostat? If that's the case, can I move the thermostat upstairs somehow?
The furnace filter filters all return air from the house, warm or cold. There is only one filter and it needs to be changed regularily (sometimes monthly depending on how often the furnace cycles on). It is generally found in the main return duct just before the furnace.
http://www.filtersusa.com/filterchanging.cfm
Your thermostat is the sensor.

[loybond]

Thanks guys, I'll change the filter today and see if it makes a difference.