Why is my house so hot??

[Patman]

It's a pretty hot day here today, it's currently 93 degrees, and my air conditioning has been running non stop since about 8am (it's now 3:30pm), but yet the main floor has stayed at a constant 81 degrees (where the thermostat is) and my bedroom is now 83 degrees (even with all the blinds completely closed)

I checked the temperature coming out of the vents though, and out of the two vents that are nearest the thermostat on the main floor, the air coming out is 65.4 degrees. The air coming out of my two bedroom vents is 65.1 degrees. So if the air coming out of them is so cool, how come my house is so hot? How can I possibly get this house any cooler right now, other than getting a larger AC unit (I've always felt the one that came with the house was too small, at 1.5 tons for an 1800 sq ft townhouse)

The only cool place in the house is the basement, it's a nice comfortable 72 degrees! (maybe I should just move our bed down there!)

(FWIW, I tried blocking off the vents in the basement in the past and all it did was make the basement hotter but did not make the upstairs any cooler)

 

[Quattro Pete]

Top floor will always feel hotter because of the sun directly heating it through the roof. The lower you go, the cooler it'll feel.

We have dual zone A/C units. The one for the upstairs is a larger unit, yet it still turns on and runs a lot more than the one downstairs.

Also, warmer air is lighter, so there is a natural tendency for the warm air to migrate toward the top of the house while the colder air travels to the bottom.

BTW, our basement also stays very cool, even though I keep all the A/C vents closed down there.

But if your A/C unit keeps running non-stop yet it can't bring the temperature down below 81F, then I'd say your unit is either broken or just too small for the job. You might also look into the quality of the insulation you have in the roof - this is important both for efficient cooling in the summer as well as heating during winter.

 

[Patman]

Originally Posted By: Quattro Pete
Top floor will always feel hotter because of the sun directly heating it through the roof. The lower you go, the cooler it'll feel.

Also, warmer air is lighter, so there is a natural tendency for the warm air to migrate toward the top of the house while the colder air travels to the bottom.

True, but the main thing I can't figure out is why the AC can't keep the temperature closer to the 65 degrees that is coming out of the vents, considering it's been running non stop all day long.

 

[Boomer]

One thing you can do is to increase the thickness of the insulation in the attic floor and the sidewalls of the house. The attic is the more important of the two. You can also buy reflective insulation and staple it between the supports under the roof on the attic side. Reflects the ir very efficiently. You can also add a large fan to pull outside air into the attic and exhaust it out the other side. I


Its always cheaper in the lo9ng run to insulate than to pay for extra air conditioning that can move all that extra heat load. Remove the load, cool the house better and save money.

 

[Quattro Pete]

Originally Posted By: Patman

True, but the main thing I can't figure out is why the AC can't keep the temperature closer to the 65 degrees that is coming out of the vents, considering it's been running non stop all day long.

I just edited my response. See above.

 

[40Deluxe]

Try taking oscillating fans,the kind on stands and placing by your registers and circulating the cool air around the house,if you have a second floor try to block the stair way off.These are the steps i take in my house and i set the thermostat at 75

 

[addyguy]

Having the exact same problem in my condo - AC just isn't keeping up. We're going to borrow a stand-alone unit from a friend that doesn't need it, and see if it can get one room tolerable!

 

[cp3]

Another possibility is the venting in the atic. There should be vents on the roof but also soffit vents to allow the cooler outside air in as the hot air moves out the top.

 

[QuOk]

I have a 2 ton unit for my 900sf house.
It just barely can keep the house 70f during the 97f heatwave outside.Most of the heat comes from the attic/roof.

My return air temp is 70,Vents 55f.

My basement is not air conditioned but stays 75f anyhow.

Your unit is undersized on a hot day like today.
Although 99% of the time it doesn't get that hot in Canada i bet.

 

[rclint]

Some options, and my opinions. I agree with the above I also added insulation to my already well insulated house.

First check your filters, they need to be clean clean in the summer to ease pulling air through. If they have any build up just clean them or replace it's a huge help.

Next think about a smaller window unit for the room you most often stay in, it's a huge help for me as I work swing shift, keep my room nice cool while the rest of the house stays a few degrees warmer, and actually reduces the power bill....it's much cheaper running the window unit than the ac unit outside !!.

Tower fans at walmart are a huge help for moving air through the house with very little to no noise. I purchased a lasko came with a built in air cleaner as well I also run it, but not sure how much good that part does, however this is the model you want for the tallness, very low to little noise, and moves a huge amount of air.

Make sure your windows are close on any screen doors etc (storm doors ?) the helps make a double seal at the doors, kinda like a dead air space, and also reduces lost inside air when going in/out.

I know this is a long time reward, but trees are also your friend. I have trees on back, and both sides of the house, the sun hits the front of my house during winter months when it's low in the sky, and in summer it hits the house in the morning, and about 5 pm it starts getting some shade, that's about 4 hours relief from the boiling sun !!

Here is a link that may help as well, I love reading over the solar powered stuff, but lots of cooling, insulating money saving ideas that are very low cost, many do it yourself etc. Scroll through it all I linked the energy conversation, but look at the top there is a huge amount of information

http://www.builditsolar.com/Projects/Conservation/conservation.htm

 

[meangreen01]

1.5 ton for 1800 ft sq house is the problem. I bet it does ok the majority of time when the OA temp is not quite so hot. Keep blinds closed, kiddies from running in/out, and make sure your filter is clean.

Rough A/C sizing guide: 1 ton per 600 ft sq.

 

[sicko]

Did it always used to be like this, or has it just gotten bad this year? Do you have an attic fan? Is it working properly?

My attic fan recently broke, and now the upstairs bedrooms are almost unbearable. I'm actually surprised at how much of a difference it makes between having an attic fan and not. I knew it made a big difference, I just didn't realize it made this big of a difference.

If you aren't familiar with them, google "attic fan" and look it up. Basically it's a fan attached to either one of the walls or roof in your attic with a thermostat attached to it. When a certain temperature is reach it starts sucking air out of the attic and blowing it outside. This forces cooler air into the attic to take its place. Like I said I knew it made a big difference, and yet I'm still surprised by how big of a difference it made since my attic fan broke.

Also, if your house is newer, or new to you, I know some people have a switch in their house (usually near the heater), that adjusts how the vents distribute air through the house. Basically there's a winter mode and a summer mode. In the summer it sends more cold air upstairs to let it cool down the house, and in the winter it sends more warm air downstairs to let it warm up the house. It's a simple thing, but once again having the wrong setting makes a large difference.

 

[hemitom]

Your unit is under sized for the heat load of today (high Humidity)in Ontario, i know its hot as [censored] here to. My house raised bungalow 1160 SQ. ft. I have a 2 ton unit with the matching coil (indoors) which is a little oversized for my home. Today its running around 20 minutes off 10 minutes at a set point of 75. Ideally your unit should be sized to run continusly,at a set temp of 70 i think, and be able to maintain the temp, which is near impossible to do. Thats why most units are oversized.

 

[rshaw125]

You may not have the volume of air needed. You're getting good vent temps but maybe there's not enough of it.Is the fan in the air handler a multi- speed one? You can turn it up to pull more air across the cooling coil.

 

[Silber Igel]

Hummmm.... checking filters is the first step. Do you have 'high efficiency' filters?? They could be restricting your air flow.

Is the air flow out of the ducts what you seem to remember or is it reduced? If the filters are OI, and air flow is markedly reduced the unit is frozen up or the fan isn't turning fast enough.

Busted fan or belt is a mechanical issue. No easy fix.

But, there's hope!!! Since you are getting 65F air out of the ducts, I'm guessing your A/C unit is working fine.

Check the coil inside the house unit for ice. Under some odd conditions.. cool, humid ambient temps or hot and lots of humidity the compressor will run too much if the thermostat is set too low. It will eventually frost and ice up the expansion coil. It will become a block of ice restricting a lot of the air flow. Sadly, the compressor still runs (because the thermostat is demanding more cool)and cool air at reduced volume is all you get ....house gets hotter and muggier. And you keep jacking the thermostat down to get cooler...causing it to freeze up more.

No need to even open anything up here. Turn the thermostat up to maybe 75 - 77 - 80 or even shut off the A/C for awhile. Turn the fan to "ON" so it runs constantly to circulate warm air over the coil and melt the ice.

Be sure to keep an eye on the condensate drains!!!! If she's frozen up you will get a huge amount of melt water and you don't want to have an overflow. And BTW, a blocked drain could let water collect in the pan and that's being sucked into the coil and frozen....so I'd check that for flow as well.

 

[Patman]

Originally Posted By: sicko
Did it always used to be like this, or has it just gotten bad this year? Do you have an attic fan? Is it working properly?



I don't have an attic fan, but since we live in a condo townhouse I'm not even sure if we would be allowed to install one.

The AC has always been like this, even when we first moved in (the house and AC were brand new then) so I suspect the size of the unit is the main problem. I just changed the furnace filter, I do that every three months, so that definitely isn't the issue. The insulation in this house is pretty good because in the colder weather our house retains the heat amazingly. We don't need to turn the furnace on until a few weeks after most of our friends turn on theirs. In the late fall when it first starts getting down into the low 30s overnight, our house will still be above 70 degrees during that time!

Because this townhouse complex is so new, the trees are still too small to provide any shade for the house.

And it's true, it doesn't often get into the 90s here, the normal high temperatures for this time of year is more like high 70s/low 80s, and so we don't even need to run the AC at all when it's like that.

 

[Quattro Pete]

Originally Posted By: meangreen01
1.5 ton for 1800 ft sq house is the problem. I bet it does ok the majority of time when the OA temp is not quite so hot. Keep blinds closed, kiddies from running in/out, and make sure your filter is clean.

Rough A/C sizing guide: 1 ton per 600 ft sq.

Out of curiosity, I checked the specs on ours... looks like we've got a 2-ton unit for downstairs and a 2.5-ton unit for upstairs. 3000 sq ft total. We usually keep our thermostat at around 77F when we're in the house during summer. It has no problem maintaining this, even when it's mid 90s outside.

 

[Patman]

Originally Posted By: Silber Igel


Is the air flow out of the ducts what you seem to remember or is it reduced? If its markedly reduced the unit is frozen up or the fan isn't turning fast enough.


Air flow feels very good, it's definitely not reduced at all compared to when new, but as mentioned, when new the AC never was able to keep up on super hot days like today either.


Quote:


The way to fix it is to turn the thermostat up to maybe 75 - 77 - 80 or even off for awhile. Turn the fan to "ON" so it runs constantly to circulate warm air over the coil and melt the ice.


I always keep the fan running constantly, even in the winter. I've got the thermostat set pretty high actually, from 6am to noon (when the sun is shining into the back window and heating up the area where the thermostat is) I have the temperature set to 81 degrees. Then I have it set to come down to 80 degrees at noon, 79 degrees at 3pm and 78 degrees by 8pm. But our house probably won't cool down below 78 until well after midnight. It's a little cooler on the main floor now, at 80 degrees, but since the sun is now moved to the front of the house where our bedroom sits, that room is now 84, even with the blinds completely closed (and they are room darkening blinds, as I was on midnight shift when we first moved in here)

We do have ceiling fans in all the bedrooms, which certainly helps, and thankfully our TV is in the basement so at least we're nice and comfy down there.

We do need to probably replace our furnace in the next year so we'll probably do the AC unit at the same time and go with a 2 ton unit or even 2.5 ton.

 

[Mr Nice]

We have a Carrier A/C unit and it has no problem cooling and keeping the house at 70 degrees, we also have a bunch of ceiling fans cooling the house. We have to use A/C 10 months out of the year down here.

I set the temp at 80 went we are not home and 69-70 when we get home.

 

[Silber Igel]

Low refrigerant?

Thermostat in wrong location for the house??

Outside units free and clear so they get plenty of cooling air?

Dirty outside coils?

It would be hard to believe... but not impossible... for the house not to have good insulation and an attic ridge vent.

I'm feeling your pain.