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  • Help settle an argument

    My folks bought and old house in town to restore and move into(oneday,cause its a money pit,see the movie"Money Pit")

    Well long story short its time for a new central air and heat system to go in.In getting bids for this one thing that comes up is the placement of the return air plennum.The lower cost is to put the plennum in the ceiling,the other is to put the plennum in the wall near the floor.

    Okay,we have heard reasons yes and reasons no as to which would be better.So factoring in all relevant data,which is the better way?
    I just need one more tool,just one!

  • #2
    Hot air rises. Why return hot air to the furnace?
    Free software for calculating bolt circles and similar: Click Here


    • #3
      No one will reply cuz you didnt use " OT: "


      • #4
        Evan said: Hot air rises. Why return hot air to the furnace?

        I say: Cold air sinks. Why return cold air to the air conditioner?

        Both statements are true.

        As for the air return, are they going to be using heat more or air conditioning more?

        I say flip a coin and do it either way. Then put in reversible ceiling fans.


        • #5
          Funny this should come up! I had an indepth discussion with one of my customers about this just a few days ago. The fellow did the same thing except he lived in the house for several years before tearing up the old interior walls to upgrade the wiring and drywall. He liked the idea about the hot air rising so he put the returns near the ceiling. He claims that the furnace starts blowing warm air faster and says his heating bills went down to a certain extent. Sounds fair to me but I wonder if the floor would be a bit colder seeing that it didn't have warm air pulled across it. BTW...This guy lives near Evan so it does get cold up there. Probably doesn't have a whole lot of use for an A/C unit.
          I have tools I don't even know I own...


          • #6
            Will be using ac more than 9 months out of the year.

            This is on topic,I am a machinist,I don't want any headaches with the folk's ac unit to keep me from making chips
            I just need one more tool,just one!


            • #7
              After 20 years of listening to a 'dual-pack' sitting on the roof over my bedroom, this DIYer bought and installed a split unit where the condenser,compressor sits on the ground near the neighbors fence and the evaporator,heater,blower console was fitted into a corner of the garage pulling return air through a filter located inches above the dining room floor.

              The dining room carpet (whitish) was ruined within 1 year in the immediate vicinity of the air plenum intake. Heavy dirt load in the air returns, I guess, was dropping out onto the carpet.

              If I had it to do over again, I would go back with a rooftop dual-pack unit. The house we now have, only requires winter heat and the return filter/intake is located 8 feet above floor. Change the filter twice per year.



              • #8
                <font face="Verdana, Arial" size="2">Originally posted by Elninio:
                No one will reply cuz you didnt use " OT: "</font>
                Oh, come on.

                Paul A.

                Paul A.

                Make it fit.
                You can't win and there is a penalty for trying!


                • #9
                  I see you are in Mississippi (I just love spelling that) adn I assume your parent's house is there also. AC is a more important factor than heat in the south. I would go with the ceiling return for that reason. Besides, it's the cheaper bid.

                  And if they really want to save on the cooling bill, get some white roof paint from Tower Paint in Florida and paint the roof with it. It will be 10 - 20 degrees cooler in the heat of summer.

                  Paul A.

                  [This message has been edited by Paul Alciatore (edited 11-23-2004).]
                  Paul A.

                  Make it fit.
                  You can't win and there is a penalty for trying!


                  • #10
                    Hummm...Ya me too Misssiissiipppii Quess they couldn't make it any longer

                    Yep,hot as hell.See that is the argument that makes the most sense to me,cold air sinks and warm rises.It seems logical that the more time the cool air has to warm up and rise the better off the ac bill would be,plus like said earlier less dirt and dust in the filter(going electro-static too).

                    Long story,too long for here is the dual pak that some a--hole ripped the folks off on.They paid out $3200 for the unit installed,only its not code in town,and the building inspector rejected it.Went back on the installer,he just went bankrupt there is a golf club in his future

                    Well no use in getting mad,new unit will be a split.New contractor will deal with me and my escrow contract terms.
                    I just need one more tool,just one!


                    • #11
                      I have had them in both locations, ceiling and near the floor. Floor location makes it easier to change the filters. The dust load is heavier with it at the floor. Most of the time it is put at floor level when the air handler is located in a space below the ceiling. If the air handler is in the attic the return is in the ceiling.

                      Personally I think it is better to have the return in the ceiling because the thermostat is half way up the wall and that is the control for the air handler. Dust load is less also especially if they have carpet. At the floor you will be cooling colder air. I also have ceiling fans in every room to help with the circulation when it is really hot.

                      I alway oversize the units by at least 1/2 ton. This seams to help with the units life and electric cost. Insulation is also key factor and depending on where the unit is and the access to it pick the type of insulation carefully. Blow in is cheap but hard to get around on in the attic without distroying it.

                      Hope this helps.


                      Electrostatic filters are great.


                      • #12
                        The systems I have seen are meant to have the return as close to the unit as possible. They are great at pushing air but not as efficient at pulling. So, I think more importantly is to make sure the system is designed to use a longer inlet if you are going to put the return towards the floor. JRouche
                        My old yahoo group. Bridgeport Mill Group



                        • #13
                          All in all, the air flow is perhaps more important than the floor/ceiling question. we had a unit here at work that was mainly for cooling the equipment in the room. It had a row of 5 10" registers above the row of racks and tables that held most of that equipment. Always had problems. When I went up in the ceiling and examined the ducts I found that two of the registers (2nd and 4th) were actually attached to the return air system. With the hot air rising from the equipment fighting the cold air coming down, a good proportion of the cold air was just going straight back to the unit and never reaching the equipment below. Insanity.

                          You need to look at the overall situation and see if the overall airflow makes sense. It would be far better to use a bit of duct for the return air if it improves the flow in the house.

                          Oversize any return duct if you are concerned about the sucking thing. But the thing is, you have a closed loop circulation. Whatever amount of air the unit delivers, IT HAS TO SUCK IN. No getting around it. The air is circulating and any choke point; in the unit, the supply ducts, the return ducts, or even in the floor plan of the house; WILL hinder the flow. You must consider it all.

                          Paul A.
                          Paul A.

                          Make it fit.
                          You can't win and there is a penalty for trying!


                          • #14
                            Had an old duplex with converted coal fired boiler system. Went to put in conventional HVAC. The upstairs HVAC and return went in the attic, the downstairs in the basement.

                            It's really a preference thing, but the filters do get dirtier when the intake is on the floor. My current house has a return vent in every room.

                            James C


                            • #15
                              Jamescal has the right idea, but most of the time the costs of doing that is a little much.
                              I have both in my house, but I didn't install it.

                              Here is my reasoning.
                              Hot air rises, true, but the thermostat should be a chin height, so anything above that doesn't matter.
                              Drafts do matter, which is why the more return air ducts, the better. Less draft.
                              Stagnant air in pockets matters, which is why you want the return air away from the registers. If you put the registers in the ceiling, and the return air in the ceiling, the air will short circuit the room. Probably won't matter, since the unit is cooling the hot air at the top of the room, thus bringing the temp down. But at what expense? What about the general circulation of the air in the room? Air with heavy moisture tend to fall to the floor, and an A/c unit does a lot of cooling by removing the humidity. (feels like it is cooler syndrone)
                              My vote is for the floor if the registers are in the ceiling. Sometimes it isn't finacially feasible, only you can decide that.
                              Also, don't oversize the unit. That is one of the worse mistakes most people make.A smaller unit runs longer, removing the moisture in the air, keeping the room/house cooler, less mildew, less chance for termites, and basically on the same energy, since smaller draws less current
                              David from jax

                              Have gun, will travel.
                              A serious accident is one that money can't fix.