Any home cooling experts out there?

[RayB]

It's warming up. It's about 28C outside. I have 2 stories plus basement. Had all the windows closed since last night. My ground floor stayed cool enough, it's about 23C at the moment while 28 outside. My top floor on the other hand is 28C.

I have central air which I haven't turned on yet. Judging by the disparity in temp between the two floors I'm wondering if it would be more economical to just get a window AC unit for upstairs? I figure if run the central air the ground floor will get cold by the time the top floor drops to comfortable temp.

Opinions?

[Blanka]

Country?
Wall construction type?
Floor type?
Glass type?
Roof type?
Insulation in wall or roof?
Heating system?
Orientation of windows?
 

[Bobulus]

I'm by no means an expert, but if your goal is to cool the top floor while leaving the bottom floor alone, and save as much money as possible while doing so, would it not be cheaper to save on the cost of a window unit and just close the vents for the 1st floor?

[gryhnd]

I'm by no means an expert, but if your goal is to cool the top floor while leaving the bottom floor alone, and save as much money as possible while doing so, would it not be cheaper to save on the cost of a window unit and just close the vents for the 1st floor?

Ditto. Close the dampers on the 1st floor (but perhaps not all the way as you don't want to create too much back pressure). My poorly constructed HVAC also benefits from a booster fan ($60) in the 2nd story supply plenum, particularly in the summers as it helps to pull the heavier cold air upstairs.

I also have had great luck with mini-split systems. I use one in my sunroom. Not as obtrusive as a window unit, but they are of course pricier.

[patrickl]

Country?
Wall construction type?
Floor type?
Glass type?
Roof type?
Insulation in wall or roof?
Heating system?
Orientation of windows?
 

If you get all that, are you then just gonna say "No, I don't know"?

[Blanka]

If you get all that, are you then just gonna say "No, I don't know"?

Do you truly think so?

[RayB]

Believe it or not there's no means to close the first floor vents other than by physically obstructing them (which is what I did in winter to help move more heat upstairs).  

I've seen window units meant for 1 room for as cheap as $99, btw.

To answer Blanka, lower Canada (Toronto), 1950s building, flat roof, asphalt roll, no attic, insulation unknown, brick exterior, new double pane windows throughout, forced air mid efficiency...  ??

[Blanka]

The heat probably comes in through the roof or through the windows then. Brick is usually a good thermal damper. Always best to tackle the source instead of trying to fight the problem with cooling.
So the best bets are:
- Renew roof insulation. Today's insulation is so good, it always pays back on gas-bills if the current insulation of the roof is 10 years or older.
- Add exterior shades to the windows of the top floor.
- Make natural ventilation possible with windows to open. Balanced mechanical ventilation is only interesting for winters if it uses heat recovery from the exhaust pipe.
- AC is NEVER needed, not even in Dubai! We lived without until the 50's, so check building habits before WW2, and there is always a local working solution to fight heat without AC.

[RayB]

Forget costs.  Just think about how good it's gonna feel to lay down spread eagled after a long day and let that cool, cool air from your new window unit wash over your sweaty balls.

  RayB likes this.


AC's been running for the last 5 hours now and the top floor is still a $#@?%damn 28C. wtf
 

[Ed_McCarron]

I've seen window units meant for 1 room for as cheap as $99, btw.

No you haven't.  You've seen window units meant for one 8' x 8' room in Alaska for as cheap as $99.

[RayB]

I've seen window units meant for 1 room for as cheap as $99, btw.

No you haven't.  You've seen window units meant for one 8' x 8' room in Alaska for as cheap as $99.

No, I was definitely in Toronto.
 

[ahofle]

Had a similar problem at our last house.  Turns out there were no return air registers upstairs (A/C was added later, the ductwork was obviously only designed for heating).  So the hot air upstairs was never sucked back down into the central A/C unit and just sit up there.  You should try to move the air upstairs down to where it can be recycled through the air conditioning, either with ceiling fans (if you have one in a location that can push air to the main level) or a portable fan pointed downstairs or similar.
This won't help you since you don't have an attic, but I ended up installing a whole house fan which was about 100 times better than our A/C.  You basically open the upstairs windows and turn it on, sucking all the hot air from upstairs and pushing it out the attic vents.  This only works in climates where it cools off in the evening (like Colorado).

[RayB]

Bingo Ahofle, There are no return air vents on the top floor, only on the ground floor (1950's building).

[Edgedamage]

Toronto here also, I just picked up a used A/C from Cragislist for $60 it's a little 5200BTU unit the name is "Forest Air by GREE" on the side it says it's made in Quebec for RONA. On low it cools a master bedroom to ball shrinking cold in 30min. Also check the superstores for cheap A/C's

[northerngames]

we use aluminum foil inside our vents to keep the cold air from getting out that way and we also leave them sealed in winter becuase we now use wood only for heating because propane is a rich mans fuel nowaday's and a total waste of money.

our propane guy wanted $250.00 a month year around and that just ain't happenin