Return air question

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  #1  
Old 05-30-18, 01:24 PM
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Return air question

I've been looking a lot into return air positioning lately in my home. I'm a sparky by trade but have had to learn some air flow rules aty current contract. What I have iny home just doesn't make sense to me. I live in Toronto Canada where -10 to 100f temps can happen very fast.

I currently have one 12 by 12 return iny basement and two 32 by 10 returns located near the floor of my raised bungalow. In the summer it stay too hot upstairs. Yety basement is freezing. One of the returns is at the top of the stairs and it's noticeably cooler near it. Am I out to lunch thinking that the best config for the returns is to have a larger one in the basement to pull the cool air in and heat it in the winter for the best Delta t and near the ceiling for the summer for the hottest air and same reason with the ability to close either vent? My house is about 1100sq ft upstairs with a 1.5ton AC unit. What size return would I need to put in to maintain static pressure in the fan?

Does anyone know where I can purchase return air grills with functioning louvers?
 
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  #2  
Old 05-30-18, 04:04 PM
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Very common with two story house. Best option is to just throttle the supply ducts down on the first floor forcing air to second. Not perfect but not a lot to work with.

Vents with louvers are available at all the big box stores!
 
  #3  
Old 05-30-18, 05:00 PM
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Sounds like you have a gas furnace and the A/C was added to it. The returns are usually installed low near the floor to pick up the cold air in the winter. That works good in the winter but in the summer you need the returns at the ceiling to draw the warm air out.

Many homes are now built with a low return and a high return with louvers on them for seasonal changes. It's pretty hard to do it later without opening the walls.

I have the same problem here. I tried a larger return in the cool basement and it didn't help much on the second floor. The hot air needs to be removed from the upper level.

Attic insulation is also very critical to second/upper floor comfort.
 
  #4  
Old 06-11-18, 01:08 PM
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Home heating and a/c duct systems have changed over the years. The best systems and the most versatile were installed with both high and low returns and supplies. For heating the low registers were used to supply the heat at the floor and the low returns were to take the cold air off the floor. In summer the high supply and returns were used for the same reason, take the hot air off the ceiling and supply the cold air from above. Today it too expensive to install duct systems this way. Today the installation practice is to install high return grills and low or high supply registers. I prefer low supply registers and both high and low return grills; use the high returns in the summer and low returns in the winter. In my home I used the 3.5" X 14" stud space in the walls for the ducts. If the ductwork is below the floor you use Hart&Cooley #650 grills and #651 single vane registers. The registers are mounted low in the wall so that when the vane (damper) is closed that upper grill is the return (summer use) and when the vane is open , that vane blocks the stud space above and the lower register is the return (winter use). For your house you may have to revamp the duct work to allow for this type of return system. I would "GOOGLE" Hart & Cooley and see who is a supplier in your area. Just remember that cold air is heavier than warm air and will fall to the lowest level in the home so you need some returns in the basement. Hope this helps
 
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