HVAC Quandry

Collapse
X
Collapse
First Prev Next Last
 
  • Filter
  • Time
  • Show
Clear All
new posts

    HVAC Quandry

    Currently sleep on the first floor, but in the process of moving the bedrooms upstairs. Scratching my head on what to do about the cooling. Just spent our first night upstairs and it has to be 10 or 15 degrees warmer up there at least. We have 2T central air unit and it keeps the downstairs cool just fine, but upstairs is still hot.

    There are two (I think) issues with the current system.

    First, there are four 8" vents leading from the basement to the attic, that then feeds the two rooms. And one of those 8" vents splits into a T in the attic. We have dampers in the basement and I shut the one off leading to the upstairs bathroom. So ultimately there are three 8" vents, followed by a T in the attic. I'm thinking this is far too much ducting. By the time it reaches the attic, it barely eeks out. I was planning on removing the four 8" ducts and replace with just one duct. In the attic, run a hard duct (not the flex stuff I have now) the entire length with tapered ends. Then tie the single duct from the basement to the attic duct. Should give me more thrust from the furnace. Having four ducts, then splitting into five I think is spreading it too thin.

    Second is we have three returns on the first floor, but not a single one on the second. Something tells me I need a return upstairs. We had the doors open last night to the downstairs though, but not sure if that does the same thing as a return.

    I'm almost at the point of closing the dampers to the upstairs, leave them all open downstairs, and run a window fan in the upstairs bedroom pulling the air out to draw in the cooler air from downstairs.

    Thoughts or suggestions?

    #2
    I have the same problem in the house we just bought. I haven't bothered tracing the ducting but have made an improvement none the less. I closed off half of the registers on the main floor and it increased the air flow on the second floor. I have given some thought to the return air but am going to leave it alone for a few days and see what happens.

    I am working with the principal that hot air rises cool air falls so with that being said I've kept the second floor windows shut during the heat of the day.

    One thing that just crossed my mind is perhaps installing booster fans to provide more flow to the second floor.

    I might just head off to youtube and see if there is anything there for pointers.

    Comment


      #3
      Originally posted by Lawless View Post
      I have the same problem in the house we just bought. I haven't bothered tracing the ducting but have made an improvement none the less. I closed off half of the registers on the main floor and it increased the air flow on the second floor. I have given some thought to the return air but am going to leave it alone for a few days and see what happens.

      I am working with the principal that hot air rises cool air falls so with that being said I've kept the second floor windows shut during the heat of the day.

      One thing that just crossed my mind is perhaps installing booster fans to provide more flow to the second floor.

      I might just head off to youtube and see if there is anything there for pointers.
      See, I was thinking that the hot air needed a place to escape out of. It just kind of dams up on the 2nd floor and has nowhere to go.

      I dug a little bit on this over the winter time, and it seems the final conclusion on the booster fans was that they are somewhat of a gimmick.

      Comment


        #4
        If it is anything like my moms old 3 level condo, you would be doing yourself a favor by adding a second unit dedicated to the top floor.
        Whenever there is doubt, there is no doubt.

        Comment


          #5
          Lots of options to choose from, if possible adding high wall returns upstairs should make a big difference. The hot air is stratified up there with nowhere to go. Throttling the dampers for downstairs to achieve a better balance could also help.

          We've done alot of work trying to get one system to cool multiple levels, but if the house and HVAC system wasn't built with that in mind the gains are minimal compared to the effort. The go to seems to be adding a single or multi head mini-split to the second floor, every customer I've talked to afterwards is thrilled with the comfort they now have.

          Comment


            #6
            Add return upstairs, throttle the downstairs dampers maximize upstairs comfort,

            or

            ductless mini split upstairs.

            Comment


              #7
              Or
              burn house down
              Collect insurance
              Party your ass off like it's 1999


              I vote move a return upstairs and throttle the feeds down stairs. Also make sure your attic is well insulated and vented, and if any ducting is in it make sure it is fucking coated in insulation.

              Comment


                #8
                Yea, we have all the dampers closed downstairs.

                We do have a window a/c I can put in the window upstairs, but we have central air so I sort of wanted to leave that as a final option.

                But yea, I'm thinking the lack of returns upstairs isn't letting the hot air escape anywhere.

                Comment


                  #9
                  Originally posted by woods View Post
                  Yea, we have all the dampers closed downstairs.

                  We do have a window a/c I can put in the window upstairs, but we have central air so I sort of wanted to leave that as a final option.

                  But yea, I'm thinking the lack of returns upstairs isn't letting the hot air escape anywhere.
                  It’s not about air “escaping”. It’s about having a delta (difference) in pressure. You are attempting to pump higher pressure air in the space. It’s like watching the weather. Weather always flows from an area of high pressure to low. The air return is your low pressure. You need it for the air to move.

                  Comment


                    #10
                    Originally posted by rugger View Post

                    It’s not about air “escaping”. It’s about having a delta (difference) in pressure. You are attempting to pump higher pressure air in the space. It’s like watching the weather. Weather always flows from an area of high pressure to low. The air return is your low pressure. You need it for the air to move.
                    I gotcha.

                    I'll have to see how bad it is to install a couple returns upstairs. We have three downstairs. Be nice if they align somewhere upstairs that I can install one. Dad's a master carpenter, so next time he's over we'll see what we can do. Think installing returns is going to be the biggest improvement.

                    Comment


                      #11
                      Install a mini split upstairs. Everything else is a waste of time. 2 tons is most likely too small anyway

                      Comment


                        #12
                        We slept upstairs last night. Placed a beefy fan at the top of the stairs to push the stagnant air downstairs. Huge difference. It was still cooler downstairs, but it was nicer. We'll stick with that for now, and when things get back to "normal", I think I'm going to grab a few doorframe fans to help circulate the air out of the rooms and into the downstairs. Start there and see what happens.

                        Comment


                          #13
                          Glad you got some relief, I fucking hate sleeping in a warm or hot room.
                          Whenever there is doubt, there is no doubt.

                          Comment


                            #14
                            how about closing all the vents in the basement and most in the first floor while opening the ones upstairs???

                            Wild theory i know, but it might just work :/

                            Comment


                              #15
                              put a multi head mini split system into every bedroom. way way better life comfort that way. you can get cassettes for in ceiling units and send the linesets out via the attic.

                              short of that its all about return air. you need to get bigger/more returns in the bedrooms.

                              Comment

                              Working...
                              X