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Originally Posted by Paulbstockton6@hotmail.co
Regarding closing off returns... you SHOULD familiarize yourself with TESP measurements (static pressure in ducts) This is easy, but you need to buy, borrow or make a manometer. You also need to verify the TR (temperature rise from return (intake) air and supply duct air temperature. Compare that to the label on the furnace.
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Good advice. Seems simple enough.
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Fan speeds... you may be able to lower the fan speed for heat... ( but, not if you don't understand the function/purpose of the above two easy to preform tests.)
Do you know what your fan speed is? For example, a 80,000 btu furnace should have a minimum of 20x25 inch duct.....
What is the size of your return duct... should be equivalent to 16" round for a 80k btu and 1200 cfm.
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Don't know my fan speed. My furnace is 125,000 BTU, with 100,000 of useful heating. I have 2 returns shown in this photo. The cylindrical vertical one is from the upstairs ceiling, and the other is on the floor of the basement with the filters sitting on top.
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Are the ducts rigid or flex?
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Flex branches; each one going to an individual register.
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Furnaces usually have a separate speed for heat and a faster speed for A/C....
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If mine does, it's not reflected in power consumption. I would think less speed is needed for AC considering 5 tons of cooling is nothing compared to 100,000 BTUs of heating.
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And, it's possible....you might spend lots of money/time and not solve your temperature stratification cheaply...( newer units will have more efficient blowers that operate more cheaply (guess around 30%?) if you want/need to run the fan more often.
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One person suggested installing more registers both upstairs and down, and that way some of the upstairs/downstairs ones can be closed depending on the season. I basically need all of my cooling to come from upstairs in the summer, and 90% of heating to come from downstairs in the winter. I've got 10 registers upstairs, and 7 down.
Here's the downstairs, with 2 bedrooms and a bathroom not pictured (behind). The white door on the left leads to the utility room where the furnace is.
The rest of the single main supply plenum
