Central air conditioner advice?

Eug

Lifer
Mar 11, 2000
23,583
996
126
Anywhere to go for good advice on central air conditioners?

I have one now, but in our 34C/93F humid weather in Toronto, it just ain't cuttin' it. It's on full blast all the time, and the place is staying at 79-80F.

Any advice on what to look for? I'm told that going too big isn't a good idea, cuz it cycles on and off too often, and doesn't dehumidify the air enough. However, clearly, the one I have right now isn't powerful enough. I don't actually know the size of the current one, or what size I need for this place (1040 square feet, over 3 floors).
 

HomeAppraiser

Platinum Member
Aug 17, 2005
2,562
1
0
A 2 ton condenser or 2.5 ton heat pump should do the trick. $900 to $1300USD to hook on to your existing duct work. Or get three cheap window a/c units at under $200 each.
 

dullard

Elite Member
May 21, 2001
24,998
3,325
126
Maybe the one you have now had a coolant leak. It may be repairable without too much cost.
 

Shame

Platinum Member
Dec 28, 2001
2,730
0
71
Originally posted by: HomeAppraiser
A 2 ton condenser or 2.5 ton heat pump should do the trick. $900 to $1300USD to hook on to your existing duct work. Or get three cheap window a/c units at under $200 each.

I'll second HomeAppraiser's 2 ton condenser recommendation... Just perfect for 1000 sq. feet.
 

Eug

Lifer
Mar 11, 2000
23,583
996
126
OK, CAD$1500 (US$1320) is within my budget. However, dullard's comment is a good one. Maybe I'll ask them to assess the current one first, for a recharge.
 

Slacker

Diamond Member
Oct 9, 1999
8,623
33
91
Originally posted by: Eug
OK, CAD$1500 (US$1320) is within my budget. However, dullard's comment is a good one. Maybe I'll ask them to assess the current one first, for a recharge.
Dont ask the folks trying to sell you a $1500 unit if you can get by with a $500 repair.......


Start the transaction as a service call to repair/recharge, let them diagnose it and findout if it is repairable and for how much, get three estimates if you need to replace it.

Look in the book, any HVAC co. can repair or install ac units.

There are two main components, the one on top of your furnace is the evaporator, the one in the wall is the condensor/compressor or yours may not be in the wall but on a pad outside.



 

rh71

No Lifer
Aug 28, 2001
52,853
1,048
126
^ prob with getting estimates is they need to hook up to your condenser and that costs money to start ($90 here). My guys told me I had a leak and it cost ~$200 to refill it but they said there's still a small leak.. unless I pay a lot more to "snake" out the leak (with dye) to find it... I was basically stuck. It's gonna cost either way... these things are expensive either way... if I could do it over, I'd just get some window units.
 

BoomerD

No Lifer
Feb 26, 2006
62,678
11,017
136
Consider how much electricity you will use with the window units. MOST aren't very "friendly" on the power bill...
I'd recommend gettting a good HVAC person to come troubleshoot your existing unit. It could be something stupidly simple, like the condensor coils needing to be cleaned, or dirty filter...OR, any of a dozen or more serious problems.
 

Eug

Lifer
Mar 11, 2000
23,583
996
126
I'm not a fan of window units. I'm short of window space as it is. Plus they're louder.

Originally posted by: Slacker
Originally posted by: Eug
OK, CAD$1500 (US$1320) is within my budget. However, dullard's comment is a good one. Maybe I'll ask them to assess the current one first, for a recharge.
Dont ask the folks trying to sell you a $1500 unit if you can get by with a $500 repair.......


Start the transaction as a service call to repair/recharge, let them diagnose it and findout if it is repairable and for how much, get three estimates if you need to replace it.

Look in the book, any HVAC co. can repair or install ac units.

There are two main components, the one on top of your furnace is the evaporator, the one in the wall is the condensor/compressor or yours may not be in the wall but on a pad outside.
My condensor/compressor is outside on my rooftop patio. (It's a townhouse.) I have nothing on top of my furnace that I know of. The air system or whatever that's called is in the ceiling in the venting.
 

BoomerD

No Lifer
Feb 26, 2006
62,678
11,017
136
Originally posted by: Eug
I'm not a fan of window units. I'm short of window space as it is. Plus they're louder.

Originally posted by: Slacker
Originally posted by: Eug
OK, CAD$1500 (US$1320) is within my budget. However, dullard's comment is a good one. Maybe I'll ask them to assess the current one first, for a recharge.
Dont ask the folks trying to sell you a $1500 unit if you can get by with a $500 repair.......


Start the transaction as a service call to repair/recharge, let them diagnose it and findout if it is repairable and for how much, get three estimates if you need to replace it.

Look in the book, any HVAC co. can repair or install ac units.

There are two main components, the one on top of your furnace is the evaporator, the one in the wall is the condensor/compressor or yours may not be in the wall but on a pad outside.
My condensor/compressor is outside on my rooftop patio. (It's a townhouse.) I have nothing on top of my furnace that I know of. The air system or whatever that's called is in the ceiling in the venting.

have you cleaned that condensor out? A good hose job can make all the difference in the world...;)
 

newmachineoverlord

Senior member
Jan 22, 2006
484
0
0
Trane and Lennox make SEER 19+ units. If you're getting a new central air unit, be sure to buy the highest efficiency model you can (call around locally). Anything less than 14.5 SEER and the person who sells it to you will know you're a noob, and that they've pwnd joo. Depending on the SEER rating of your current unit, it may be more economical in the long run to just replace it with a high efficiency unit even if it just needs to be cleaned. That said, be sure to clean the one you have off first to see if that helps. You've been changing/cleaning your air filters too, right?

Also, you didn't post the size of your current a/c unit. If you already have a 2.0 ton/24,000BTU a/c unit, and it isn't cutting it, then we're giving you bad advice that doesn't cut it for your poorly insulated/heavily insolated house. In that case, I would advise you to just get something that's .5ton/6000BTU bigger than the one you already have, and get a home energy audit and see if you can add insulation. The size and SEER should be posted somewhere on the unit.

Window units should be avoided if you have the option of central air, as they are far less energy efficient.
 

BoomerD

No Lifer
Feb 26, 2006
62,678
11,017
136
In addition to insulation, what do you have for windows? The older single pane windows are terribly inefficient, and replacing them with quality double-pane windows can pay for themselves in a couple of years with the energy savings alone.
 

Eug

Lifer
Mar 11, 2000
23,583
996
126
My windows are modern dual pane.

My a/c unit doesn't list those specs. It says the the compressor is 1.5 HP though.

I found this page that gives these conversions:

Where HP = Horse Power and kW = kilowatt.
1 HP = 2.55kW
1.5 HP = 3.5 kW
2 HP = 5.1 kW
2.5 HP = 6 kW
3 HP = 7 kW
4 HP = 8 kW
5 HP = 12 kW
6 HP = 14 kW
8 HP = 16 kW
9 HP = 21 kW

3412 BTU = 1 kW.

If I need a 240000 BTU unit, then that's 7 kW, which is 3 HP.

Ie. It looks like my A/C unit is grossly underpowered, assuming my calculations are correct.

However, in some ways humidity is even more of a concern than the temperature. For that reason, some pages advise slightly underpowered is better than grossly overpowered, because if it's on longer it remove more moisture. Does that mean a 6 kW (2.5 HP) unit would also be OK? If so, that's a little under 21000 BTU. 18000 BTU (5.3 HP) seems too small though.

So, it looks to me that something in the 21000 to 24000 range (the latter already being suggested) is right for me. Somehow I knew my A/C unit was too small, I've seen something similar used in apts overseas that were maybe only 2/3rds the size of my townhouse.
 

Eug

Lifer
Mar 11, 2000
23,583
996
126
Originally posted by: newmachineoverlord
Trane and Lennox make SEER 19+ units. If you're getting a new central air unit, be sure to buy the highest efficiency model you can (call around locally). Anything less than 14.5 SEER and the person who sells it to you will know you're a noob, and that they've pwnd joo.
Well, I plan to move within 2 years.

Also, I note that on this page that the standard seems to be SEER 13 for 2 ton units, with only a few above 15.

I'm thinking that if a 13.0 one is cheap, and a 15 one is $$$$, it might just make more sense for me to get the 13 since I'm not going to be around here for more than a couple of years. Comments?