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$400 dif between heat and cooling months, getting ready for the AZ Summer early

$400 dif between heat and cooling months, getting ready for the AZ Summer early


  #1  
Old 01-07-11, 07:15 AM
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$400 dif between heat and cooling months, getting ready for the AZ Summer early

Not sure if this is the right place but right now here in AZ its been in the 30's at night and maybe the low 60's during the day and my heater for the house has been running quite a bit. The last two months my electric bills have been $115ish give or take a couple dollars. The heater is running a good deal but obviously not as much as it does in the summer time. What concerns me is in the summer my electric bill racks in anywhere from $450-$500. During the day I keep the temp at 83-84 in house and turn it down to 79 at night. I do have pool in which the pump runs about 5hrs a day as well in summer. All my friend and even co-workers do not have this big of a jump in bill differences (most say double the cooler months). Its a 2000sqft home and this just seems like a huge difference in price. I have a friend who has a 4500sqft home and his bill doesn't get near mine. My next step is to change out two doors and add more insulation in the attic but what else should I do? Should I get someone in for an energy audit, should I focus on the AC unit as possibly having an issue that is causing it to pull more current, etc? Im kind of lost here and not sure where I should start spending money first to get the quickest gains back. Any info would be great.

House was built in 85' 2 story
Mostly large Window's (74"x74" split single pain glass)
Attic is over half of house
Tile roofing
Electric everything, no gas
 
  #2  
Old 01-07-11, 09:08 AM
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Hi ff..
I'm a little further north than you...but I think one big problem is probably your windows. Single pane is like a giant hole in the wall. Mine are double pane with solar film on the 2 large ones that get sun. The film helps but I really need newer more efficient stuff or to get the windows reglazed with double pane LoE. Your area probably gets a lot of solar heating (as do we). If your windows are facing the sun, it's coming through and putting a big load on your A/C. It's also possible your unit was sized for heating (doesn't need to be as big as other colder areas), and has to run constantly in the summer.

Air sealing the living space from the attic and adding insulation are both relatively cheap and won't hurt.

What kind of construction? Stucco on wood frame, like 95% of them? What thickness are your walls?

Also...you used the terms heater and AC...is it one unit? A heat pump? Or real electric heat with a separate A/C?
 
  #3  
Old 01-07-11, 09:49 AM
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I do have sun screens on most windows that get hit by the sun, one thing that is is my favor though is my house is North/South exposure and there is really no direct sunlight that can beat in through the windows. My last place was East/West exposure and when the sun came up the house baked up quickly. I had dabbled with the idea of new windows but I just don't have the funding, plus I read a lot about issues after replacing windows that were on a stucco based house due to the water barriers and such. Yes the house is Stucco on wood, as for the thickness I'm not really sure. The drywall is all 5/8's from what I have came across and framing is 2x4 I think.

I do realize single pane windows are not very energy friendly but three other houses my buddies have are the same way and their costs between winter/summer are nowhere near as drastic. Maybe they need to be sealed up better, who knows but as warm as I keep my place during the day in summer the costs are not adding up and saving me money.

The unit I have is on my roof is a York (don't remember model number right now) but it is a heater/AC in one so its one large unit and there is a heat pump.
 
  #4  
Old 01-07-11, 10:25 AM
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I'll let some of the Pro's comment ..but I'll throw these out.

I can't give you a comparison, since you're summer temps are higher than ours and yer a bit further south and lower elevation.

As a rule keeping a constant temp with a heatpump is the way to go. Try and find something in between your setpoints that feels comfortable. Allowing the interior to heat soak takes a lot to cool it off.

You can easily find you exterior stud thickness by measuring the frame of your exterior door. 5 1/2" or so will be 2x4, 7 1/2" will be 2x6. That can give an idea of the insulation.

Check the type and depth of installed insulation in the attic. Do you have adequate attic ventilation?
 
  #5  
Old 01-07-11, 10:32 AM
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Framing would be 2x4 then, as for attic ventilation, I would think I have a good amount. I do have two open areas screened over on each side, its all blown insulation up there as well.
 
  #6  
Old 01-07-11, 12:57 PM
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You may have the gable vents near the peak...but do you have roof or soffit vents?

On a sunny summer day in the 80's...my attic can easily reach over 140 or more (higher near the peak). Unfortunately due to the type of construction I wont be able to add more venting without quite a lot of work.

Using my infrared non-contact thermometer...the interior ceilings might reach 85-90 (again, more in the vaulted rooms) ...basically just radiating heat into the affected areas.

There's a rule for attic venting, but I just can't remember it exactly. Something like 1 sf per 300 sf of attic...divided between intake and exhaust. Don't quote me on that..just an example. In our climates...I think more is better. I'd rather have 110 air blowing through than 150 air just sitting in there.
 
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Old 01-07-11, 02:59 PM
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Divide the number of Square Feet of roof over conditioned living space by 150 to get the number of Square Inches of combined inlet and exhaust. You can effectively use the footprint of the conditioned living space to get a usable answer. You want the inlet and exhaust areas to be roughly equal. (Ex. 3000 SF house / 150 = 200 sq inches total ventilation. Divide by 2 to get areas of inlet and outlet.)

Placement of vents requires some attention to detail. Ideally, you want 3' or more vertical separation between inlet and exhaust vents. Eave soffit vents work very well for inlets because they are pretty well protected from weather infiltration and are easy to install. However, for these passive ventilators to work, they cannot be blocked by the attic insulation. There are ventilation channels that install between the rafters and run down to the eave vents in order to hold back the insulation.

Gable end wall vents are supposed to be exhaust vents and they will function as such if they are high enough up the wall and if there is adequate inlet vent area. If not, the ventilation "system" will try to equalize by using part of the area of the gable vent for inlet and the upper part for exhaust.

I prefer ridge vents, partly because they provide maximum vertical separation, but also because they provide the cleanest appearance. Ridge vent products for shingle, metal and tile roofs are manufactured and sold by Lomanco, Inc. among others. Lomanco offers products for all types of structural ventilation applications, both powered and passive, and there is a lot of good information about ventilating on their website Lomanco, Inc.Ventilation Products. I guess where I'm going with all this is that even though it seems like an afterthought, Gunguy's suggestion to look at your attic ventilation my well be the most cost effective solution to reducing your summertime utility bills.

I like to harp on ventilation because it's such an easy target. I have seen government figures that over 90% of residences in the United States are not properly ventilated. That's not a majority you really want to be in.

Good luck with all this.
Doug Thompson
GC builder/remodeler
 
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Old 01-09-11, 08:19 AM
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Thanks tldoug, that was a lot of info and I am confused on a few things but will just research what they are. From here, what step should I do. Do I need to bring someone in with an infrared or go another route? Are there certain time frames when certain ventilation was used over another? Did they use something in the 70's then decide it was more practical in the 80's to go with a different set-up, etc? I guess I will start with the attic and work my way down.

On a side note, even in the summer it doesn't seem my AC needs to run all that much to cool down my house, but the bills are telling me it does so I wasn't sure if this was an issue with my unit pulling to much current or something causing the prices to go through the roof literally.

Thanks
 
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Old 01-09-11, 08:24 AM
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I forgot something...
You need to check your rates between summer and winter....seems like they add on charges when you go over a certain amount of usage?

Might want to check to see if the utility offers any discounts on energy audits as well.
 
  #10  
Old 11-26-12, 09:16 AM
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Just wondering if you were able to isolate and identify the problem(s) you were having. I live in Chandler, and am experiencing the same situation.
 
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Old 11-29-12, 08:14 AM
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Just wondering if you were able to isolate and identify the problem(s) you were having. I live in Chandler, and am experiencing the same situation.
I'm in Tempe, it's all about insulation and ventilation.

How hot does your attic get in the summer? If it's too hot, you need to ventilate it, maybe passively, maybe actively. There's a reason that older houses had those gable vents.

Is your garage hot in the evenings after you get home, but not as hot in the afternoon on weekends when you haven't left the house? If so, your vehicle engine block is radiating its heat into the garage, which is in turn conducting into the house. We're considering removing everything possible from our garage so that the door can be left open for a couple of hours in the afternoon to let the waste heat vent outside.

What color and material is the roof? The lighter and more reflective, the less heat retained by the roof.

What is the house made out of? If it's concrete block construction and if the sun is shining on the walls, that house is absorbing and retaining heat, and releasing it into the house. Layers of insulation and stucco on the outside can reduce this.

Single pane windows are bad. My house has what are arguably high end single pane windows from when it was built in the seventies, and they're coming out.

Leaks around doors and windows are also a problem. Fix them.

Reduce the temperature on your hot water heater(s) in the summer.

How old are the HVAC system(s)? The older, the less efficient.

How low do you cool the house to? We cool to 85 during the day, and to 78-80 when we're home.

Do you take advantage of naturally cool air in the evenings in the spring and fall? When it's cooler outside than inside, turn off the AC (and possibly manually engage the fan) and open the windows. Let the outside air cool the house for free.
 
  #12  
Old 11-30-12, 07:59 PM
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JRNYMAN, if you enter the specific information for your house into the ZIP-Code Insulation Program - an online calculator - it will tell you the most effective way to add insulation. If you read the report it gives you carefully, it will also help you decide what changes you might make to your HVAC system and other major loads.

That said, focusing on ventilation may be the most effective immediate strategy. While the primary purpose of attic ventilation is to keep the attic insulation dry and effective during the heating season, it can also help reduce the thermal load during the cooling season. A whole house fan can also be aa high-return improvement.
 
  #13  
Old 12-12-12, 11:15 AM
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Thanks for the reply Nashkat1. I'll check it out.
 
 

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