CDeb Posted July 20, 2008 Share Posted July 20, 2008 In general, 1 ton should cool 400 square feet.I had always heard 1 ton for every 600 sqft. Am I nuts? Link to comment Share on other sites More sharing options...
musicman Posted July 20, 2008 Share Posted July 20, 2008 I had always heard 1 ton for every 600 sqft. Am I nuts?it depends how efficient the home is. 400 is more accurate for a less efficient home. a properly insulated home with better windows should need significantly less. Link to comment Share on other sites More sharing options...
RedScare Posted July 20, 2008 Share Posted July 20, 2008 I had always heard 1 ton for every 600 sqft. Am I nuts? No, we are for living in 90 year old homes. Link to comment Share on other sites More sharing options...
jm1fd Posted July 20, 2008 Share Posted July 20, 2008 The upstairs unit is a Kenmore TCA236AKA4. The downstairs package unit says "International Comfort Products" with a model PGAD36E1K6. Not sure if this is really what is inside the box. The old woman we bought the house from was pretty clueless about it (and she owned the house since the 80s). No one did much to the house in 70 years (thankfully) because everything they did do, we are having to undo.Oh, and we got under the house this morning. Ignoring the foundation issues (4 piers not touching their respective beams), we can feel cool air leaking in a few places. It felt quite nice down there, LOL.The downstairs unit appears to be 3 tons, as evidenced by the 36 in the model number. The upstairs unit looks to be 3 tons as well. WAAAAY too much A/C. You might try cooling the house by using one of the units and some strategically placed fans. Probably the upstairs unit since the cool air would flow down. I suggest you look into a new system(s) this fall when the HVAC companies don't have anything going on and are willing to negotiate.A little bit of cool air leaking in one or two spots shouldn't concern you that much. If you've got a whole duct full pouring out in one spot, then you should be worried.it depends how efficient the home is. 400 is more accurate for a less efficient home. a properly insulated home with better windows should need significantly less.Indeed. You should never go on the rule of thumb X number of tons per square foot when sizing central A/C. They have methods for calculating the exact heat load & heat loss of the house. Some houses might be 300sqft/ton if they have lots of glass on the west side of the house. Some houses will be 800sqft/ton if they're well insulated, shaded, etc. Link to comment Share on other sites More sharing options...
RedScare Posted July 20, 2008 Share Posted July 20, 2008 This has all been very enlightening, thanks for the feedback.Our usage since purchasing the home in October:November 987December 1084January 870February 793March 1089April 1160May 1434June 3449When we had the house inspected, the inspector's air heat sensor showed the AC was blowing in the 5x-degree range, which we were told was good. In fact, the upstairs unit blows so strong we had to put air diverters on the vents to keep from freezing when the AC comes on. It is definitely oversized...our neighbor said he thought it was either a 4-ton or very close to it.I definitely feel cool air when i put my hand in front of any of the crawlspace vents. We need to address the package unit before going any further, I believe. It's probably a mess inside and we are now paying for not having focused enough on it in the beginning.Am I just that energy concious, or are all of these numbers high? My usage is 1/2 (or less) of yours for every single month. And, I know you did not use AC in December through February. Assuming that you are interested in cutting your electricity consumption (the purpose of this thread), you might consider doing an inventory of your electricity usage. Some think it is overkill, or that it does little good, but when I use 329 kwh in February versus your 793, I don't think that is chump change. I use either CFL bulbs or dimmers, I turn off lights and fans when not in use, I run the thermostat at 78 (comfortable for me), and at 80 when gone, and I resisted the urge to buy an energy hog plasma TV. I unplugged the freezer in the garage and filled in gaps in my windows. Total cost , except for the dimmers was around 50 bucks. Dimmers were about $30-40 each for about 8. I have not done any of the expensive stuff like radiant barriers and wall insulation, or double pane windows. Link to comment Share on other sites More sharing options...
musicman Posted July 20, 2008 Share Posted July 20, 2008 Am I just that energy concious, or are all of these numbers high? My usage is 1/2 (or less) of yours for every single month.I'm with you.March 322.0 April 451.0 May 461.0 Link to comment Share on other sites More sharing options...
travelguy_73 Posted July 20, 2008 Author Share Posted July 20, 2008 This has been very enlightening, but very depressing, LOL. And I really appreciate you guys all taking the time to offer up advice and thoughts (especially those with older homes because we really are talking apples to apples). We don't consider ourselves energy wasters. There are only two of us, one plasma TV, one (new energy star) refrigerator, and a computer that is probably on more than it should be. We program the thermostats, keep the blinds closed, and don't run the AC below 76, more like 77, when we are home. We have lights on timers, and the only extra lighting we have are landscape lights. We have like 30 (original) windows in the house, they are everywhere and we love them. They were sealed up until we had the house painted and wanted them operational. With that said, we have cellular shades in all of the windows, which is supposed to have a decent R-value (for window coverings). So hopefully the shades do negate much of the window inefficiency. We are actually going to try the idea of cooling the house with the upstairs unit. We need to relocate the unit to where it is next to the downstairs (they are on opposite sides of the house for whatever reason). Perhaps we can have all of the ducts sealed up, and then tie it all to the one unit. Who knows, I need a good a/c guy out to offer up some options. I am just wary of a $10k bill to replace it all. The downstairs (package) unit has been running a lot this morning...like 30 minutes at a time. Will get it checked out ASAP. Am I just that energy concious, or are all of these numbers high? My usage is 1/2 (or less) of yours for every single month. Up until now, we didn't have a good grasp on what our usage should be . We used to live in a loft downtown, and so didn't pay much at all, It was all-electric and newly rehabbed, so the bills were pretty consistent from month-to-month. Link to comment Share on other sites More sharing options...
mkultra25 Posted July 20, 2008 Share Posted July 20, 2008 Our house is 62 years old and about 2300 sf. Usage for May was roughly 1800 kWh (I don't have June usage at hand right now). New roof was installed about 4 years ago, and radiant barrier decking was put in at that time along with ridge vents (old roof was 20-year-old composite shingles over original wood shingles, with only soffit vents). New HVAC system (5-ton Trane XR13) was installed 2 years ago to replace an 18-year-old Carrier, and 12" of cellulose insulation was blown in the attic also. Original windows are still present in the majority of the house - part of it is a later addition with much more energy-efficient vinyl windows. All exterior doors have had new weatherstripping installed within the past year or so. Thermostat is set at 77 during the summer, 68-70 during the winter, and both the furnace and AC units are serviced annually. No plasma TV, just a big (36") CRT. Fridge, washer, and dryer are all about 9 years old. Lights are off when not actually in use, and CFLs have been installed where possible, but the room we spend the most time in has recessed can lighting, so CFLs are not really usable there. And there's the home network: two computers, two CRT monitors, two external HDDs, printer, scanner, wireless router, external speakers with powered subwoofer, all running 24/7. The machines are actually in use a fair amount of that time, so it's not really practical to power the entire network up and down repeatedly during the course of the day.The things that made the biggest difference in energy usage were the new HVAC system and probably the radiant barrier. If you have an old HVAC system, a new one will pay for itself in a surprisingly short period of time. Link to comment Share on other sites More sharing options...
sevfiv Posted July 21, 2008 Share Posted July 21, 2008 I'm with you.March 322.0 April 451.0 May 461.0I'm with you also - reading all those high numbers makes me grateful for living small and modest...!March 220April 239May 313oh, and my place is about 50 years old Link to comment Share on other sites More sharing options...
cgallagher Posted July 21, 2008 Share Posted July 21, 2008 The best thing you can do is go ahead a pay for the spray on radiant barrier in the attic. It will cool your attic space down about 20-30 degrees. And since the machine and ductwork that cools your home down is located in this space, it has to work much harder when the temperature is 145 degrees as apposed to 125 degrees. Some new homes are incorporating machine rooms that are insulated and cooled. This helps out with the energy efficiency quite a bit. With the rise in natural gas prices, we will all be experiencing drastic increases in our electric bills over the next year. My bill also doubled this month. We could open up more drilling on the Florida coast... Natural gas drilling is clean and has minimum enviormental impact. I guess when the Florida residents realize that no one can afford to drive to see their beautiful beaches, they will probably decide it's worth it to add a few wells here and there. Link to comment Share on other sites More sharing options...
TAK Posted August 5, 2008 Share Posted August 5, 2008 This has all been very enlightening, thanks for the feedback.Our usage since purchasing the home in October:November 987December 1084January 870February 793March 1089April 1160May 1434June 3449When we had the house inspected, the inspector's air heat sensor showed the AC was blowing in the 5x-degree range, which we were told was good. In fact, the upstairs unit blows so strong we had to put air diverters on the vents to keep from freezing when the AC comes on. It is definitely oversized...our neighbor said he thought it was either a 4-ton or very close to it.I definitely feel cool air when i put my hand in front of any of the crawlspace vents. We need to address the package unit before going any further, I believe. It's probably a mess inside and we are now paying for not having focused enough on it in the beginning.i know i'm way late on this, but i'd have them come out and read the meter again - with me standing there to see what number they came up with. then i'd have them test or change the meter.3449 kwh is a lot... a lot.i work at home, my wife is at home, and we have two boys... and we burn about half that with the A/C constantly set at 76, in a badly insulated house.something's amiss. Link to comment Share on other sites More sharing options...
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