Oil furnace garage

Old 10-15-13, 06:30 AM
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Oil furnace garage

I've bought an old o�l furnace to heat my 26X32 garage, I have a question for the air return. I've had several opignon on this and would like to know the right way. They will be a 16 feet duct running from the plenum accros the ceiling, with the required opening to push the heat out. Now for the air return the guy making the ducts told me to just cap off the opening and put a little duct that will pull the air into the air return. Now other people have been telling me to run that duct to the floor, because it needs to pull colder air. Just wondering the right way here?
Old 10-15-13, 07:33 PM
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It doesn't matter where you pull your return air from in this case. Just remember to make sure it's at least as large as you supply.You will only get as much heat out as return going back. With little or no return air it's like filling a straw with water and putting your finger on one end. Nothing happens. Same with warm air. If you don't have enough your blower will also work harder to move the air.
Old 10-15-13, 07:42 PM
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Normally, you would want to pull the cold air off the floor but in a garage I don't suggest any returns less than 18" from the floor. BTW, the burner must be at least 18" off the floor as well.
Old 10-15-13, 07:43 PM
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If your return air duct is too small you will not have enough airflow across the heat exchanger. This will cause the temperature rise across the heat exchanger to exceed the maximum allowed by the manufacturer and quite possibly end up destroying the heat exchanger.

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