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  • Bigger energy hog: Heat or air conditioning?

    I've always been under the impression that running your furnace was less costly than running the air conditioning.

    I've had somebody contradict this, and I've failed to find anything online (at least, not within a 2 minute Google search) so I'm putting it to the WAB.

    All other things being equal, which runs up your electric bill faster? Running the furnace or the air conditioning unit?
    “He was the most prodigious personification of all human inferiorities. He was an utterly incapable, unadapted, irresponsible, psychopathic personality, full of empty, infantile fantasies, but cursed with the keen intuition of a rat or a guttersnipe. He represented the shadow, the inferior part of everybody’s personality, in an overwhelming degree, and this was another reason why they fell for him.”

  • #2
    Originally posted by TopHatter View Post
    I've always been under the impression that running your furnace was less costly than running the air conditioning.

    I've had somebody contradict this, and I've failed to find anything online (at least, not within a 2 minute Google search) so I'm putting it to the WAB.

    All other things being equal, which runs up your electric bill faster? Running the furnace or the air conditioning unit?
    Pheonix AZ air-conditioners cost more.
    Fairbanks AK heaters cost more.
    Have lived in both so this is from personal knowledge.

    Comment


    • #3
      It's not the furnace....it's the gas that supplies the furnace especially if the furnace is rated 95 percent energy efficient and......you have a renter who thinks nothing of hiking the thermostat up to 72
      Welcome, you step into a forum of the flash bang, chew toy hell, and shove it down your throat brutal honesty. OoE

      Comment


      • #4
        The biggest energy hog is the fan that pushes all the air around the house. Ever notice all the flex they install in new construction? Even a brain dead monkey can hook up each end rather quickly so it is much cheaper to install than hard pipe. The problem is that all that flex creates more drag so the fan need to work harder to push the air through the duct. The harder the fan has to work the more expensive it is to run. That cheaper install of flex cost the owner money down the road. It always amazes me how many homes are still uninsulated or under insulated. Insulation, with very few exceptions, always pays for itself.

        Thermodynamically speaking there is a difference between heating and cooling air. When you cool the air you must deal with the latent heat of water. therefore it takes a bit more energy to cool air than to heat it.

        What muddies up the water is that there are hundreds of different units that all vary in their efficiencies. What further complicates things is that the first impulse is to say the higher efficiency unit would be the cheapest route. Unfortunately you can end up paying quite a premium just to purchase the most efficient, then, here is the kicker, the more efficient units are more complicated and have more parts that can go bad. That translates into more and more costly repairs and the unit may not last as long as its less efficient counterpart. So when shopping for a new unit, note the efficiency, and look beyond to the reliability and longevity of the unit as well.
        Removing a single turd from the cesspool doesn't make any difference.

        Comment


        • #5
          From another perspective. TH
          I can say from my college years that the air conditioner cost more.
          I scored much more in the winter with a warm bed and a cold apartment, ie furnace turned off. In the summer, air conditioner turned off, all you have is two sweaty pigs standing in front of the open refrigerator. Scoring was much more difficult and more expensive as it usually involved going out to a place that turned their air conditioner on.
          Removing a single turd from the cesspool doesn't make any difference.

          Comment


          • #6
            air-conditioning is inherently more efficient than heating (that is, it takes less energy to cool a given space by 1 degree than to heat it by the same amount).
            Naturally it depends on your preferences and longitudal location... but as you said all other things being equal, Air Conditioning is more effecient from a purely energy-consumption standpoint.



            Wired Magazine Article
            "The way to a man's heart is through his stomach...just make sure you thrust upward through his ribcage."

            Comment


            • #7
              I knew one day someone would ask a HVAC question. This is one is right up my alley!

              First you have to consider the SEER(seasonal energy efficiency rating) This is the rating given to establish cooling efficiency. The higher the better of course with the typical rating 15 years ago being around 10. Units today can reach as high as 18(and you pay dearly for it) The median affordable now is around 14 and this is pretty good.

              Heating depends on the type, gas or electric. Natural gas is different from propane and thier efficiency is measured in percentage of lost heat. In a typical 80% efficient unit, 20% of the heat produced goes out the flue. It all depends on how efficiently a unit can transfer the heat in the exchanger. Some gas units can now reach upwards of 97% efficiency. A good way to visualize the need for a higher efficiency unit is to consider that if you have a 80% unit and you have a $100 gas bill(that being the only gas appliance) $20 dollars of that went right out the flue.

              Electric heat is two types as well. You have resistance heat which is like an electric space heater using a coil or element to produce heat. Though efficient, very expensive.

              Next you have a heat pump. Basically that is an air conditioner running in reverse. Instead of it removing heat from the house and putting it outside, it is gatherring heat energy from outside and bringing it in. These are getting more efficient and are the best bet in most climates IMO. These still have different types of units as to where they excange the heat to. There are ground based HPs and Air excange HPs.

              The are other types of heating available to augment and improve existing systems. You could have a hydronic unit that utilizes an outdoor boiler that burns wood or some other fuel to heat liquid that could augment your space heating unit and also provide domestic use hot water.

              You could also use another type of system that recovers lost heat. You could actually remove heat from the house and use it to heat water for domestic use with the proper type unit.

              So to answer your question, it wholly depends on the type system you have and the climate in your region.

              On a side, my wife and I are currently looking to move farther out of town, would really like a farm, and are planning to build. I have designed a ground based HP, solar augmented, wood burning augmented system that should heat and cool the house and provide hot water. It is adaptable to the season for providing peak efficiency with whatever fuel is available or cheapest at the time. Should cost an around an average of $50 to $60 a month to heat or cool. Initial investment will be about $5000 for material and equipment. Labor is where I really come out ahead since the industry standard is about 100% percent. Glad I have a license!:)

              Comment


              • #8
                Originally posted by 7thsfsniper View Post
                So to answer your question, it wholly depends on the type system you have and the climate in your region.
                Electric heat, no gas lines down here, can't bury 'em deep enough...which is also why buried cable gets chopped up all the time :(

                Climate: Southwest Florida, hideously hot and humid most of the time. Winters are incredibly mild, although this one has been rather "crisp".

                I think my possible misapprehension comes from the fact I'm from Illinois, so there's natural gas up there, but electric down here...but I'm still used to thinking in terms of Heat=cheaper than a/c
                “He was the most prodigious personification of all human inferiorities. He was an utterly incapable, unadapted, irresponsible, psychopathic personality, full of empty, infantile fantasies, but cursed with the keen intuition of a rat or a guttersnipe. He represented the shadow, the inferior part of everybody’s personality, in an overwhelming degree, and this was another reason why they fell for him.”

                Comment


                • #9
                  You only need heating a few months out of the year, so cooling is definitely going to cost more, but only because of the length of time it is required.

                  There are many factors that affect the efficiency of your cooling unit. Sizing is VERY important when it comes to the comfort level in a space. If your unit kicks off during the heat of the the day on the hottest days, you have too large a unit that lessens the run time of the unit which has less to do with cooling than it does de-humidification. Electric resistance heat would cost more to operate over time than a heat pump, but the HP costs more primarily.

                  In your temperate zone though, a properly sized, 14 SEER or above, heat pump would cost about the same to operate in cooling or heating mode.

                  Comment


                  • #10
                    Is it also true that you can no longer fix your old AC system because of new Freon regulations? Thanks in advance.
                    Wolf Hunter

                    Comment


                    • #11
                      Originally posted by Ararat View Post
                      Is it also true that you can no longer fix your old AC system because of new Freon regulations? Thanks in advance.
                      It been that way for quite sometime now. In order to purchase certain refrigerants(freon is a brand name) like R12, R-22 containing CFCs(chloroflourocarbons) and other types containing HCFCs(hydrochlorofluorocarbons).

                      You must pass an EPA test and certify that you know and agree to practice safe handling and storage under penalty of law.

                      The Clean Air act of 1990 and the Montreal protocol are two of the major laws covering this.

                      Comment


                      • #12
                        Originally posted by 7thsfsniper View Post
                        I knew one day someone would ask a HVAC question. This is one is right up my alley!

                        First you have to consider the SEER(seasonal energy efficiency rating) This is the rating given to establish cooling efficiency. The higher the better of course with the typical rating 15 years ago being around 10. Units today can reach as high as 18(and you pay dearly for it) The median affordable now is around 14 and this is pretty good.

                        Heating depends on the type, gas or electric. Natural gas is different from propane and thier efficiency is measured in percentage of lost heat. In a typical 80% efficient unit, 20% of the heat produced goes out the flue. It all depends on how efficiently a unit can transfer the heat in the exchanger. Some gas units can now reach upwards of 97% efficiency. A good way to visualize the need for a higher efficiency unit is to consider that if you have a 80% unit and you have a $100 gas bill(that being the only gas appliance) $20 dollars of that went right out the flue.

                        Electric heat is two types as well. You have resistance heat which is like an electric space heater using a coil or element to produce heat. Though efficient, very expensive.

                        Next you have a heat pump. Basically that is an air conditioner running in reverse. Instead of it removing heat from the house and putting it outside, it is gatherring heat energy from outside and bringing it in. These are getting more efficient and are the best bet in most climates IMO. These still have different types of units as to where they excange the heat to. There are ground based HPs and Air excange HPs.

                        The are other types of heating available to augment and improve existing systems. You could have a hydronic unit that utilizes an outdoor boiler that burns wood or some other fuel to heat liquid that could augment your space heating unit and also provide domestic use hot water.

                        You could also use another type of system that recovers lost heat. You could actually remove heat from the house and use it to heat water for domestic use with the proper type unit.

                        So to answer your question, it wholly depends on the type system you have and the climate in your region.

                        On a side, my wife and I are currently looking to move farther out of town, would really like a farm, and are planning to build. I have designed a ground based HP, solar augmented, wood burning augmented system that should heat and cool the house and provide hot water. It is adaptable to the season for providing peak efficiency with whatever fuel is available or cheapest at the time. Should cost an around an average of $50 to $60 a month to heat or cool. Initial investment will be about $5000 for material and equipment. Labor is where I really come out ahead since the industry standard is about 100% percent. Glad I have a license!:)
                        The above post is the reason I subcontract all my HVAC work.

                        HVAC was the hardest part of the General Contractors license exam for me.

                        I would rather go to the dentist than have to figure unit size, duct size, returns, ect for all of the above. Throw in boilers and water chilling units for commercial with all of the valves, bypass controls, circulating pumps and I am willing to pay through the nose to have someone else do the brain work for me;)
                        Last edited by Gun Grape; 17 Mar 10,, 23:28.

                        Comment


                        • #13
                          Originally posted by Gun Grape View Post
                          The above post is the reason I subcontract all my HVAC work.

                          HVAC was the hardest part of the General Contractors license exam for me.

                          I would rather go to the dentist than have to figure unit size, duct size, returns, ect for all of the above. Throw in boilers and water chilling units for commercial with all of the valves, bypass controls, circulating pumps and I am willing to pay through the nose to have someone else do the brain work for me;)
                          I may have to print this out and post it on the job site. Out west, Sheet metal workers are looked upon as the red headed bastard stepchildren of the trades. Most people have absolutely no clue as what is involved in this kind of work and I am guessing you have only experienced the residential and maybe the light commercial aspect of the trade.
                          Removing a single turd from the cesspool doesn't make any difference.

                          Comment


                          • #14
                            Originally posted by bonehead View Post
                            Out west, Sheet metal workers are looked upon as the red headed bastard stepchildren of the trades.
                            It just isn't out west and no offense, but I see a dozen installers come and go compared to technicians. Of course its hard to give a damn about a job when your making only a couple bucks over minimum.

                            Comment


                            • #15
                              Originally posted by bonehead View Post
                              I may have to print this out and post it on the job site. Out west, Sheet metal workers are looked upon as the red headed bastard stepchildren of the trades. Most people have absolutely no clue as what is involved in this kind of work and I am guessing you have only experienced the residential and maybe the light commercial aspect of the trade.
                              Commercial and light industry. I don't do residential. Then again not to many builders are doing residential construction in Florida right now

                              Comment

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