Barometric dampers are great, but they require considerable installation or
Your cooler shoud already be set up with a simple damper system. Just
below the blower, outside the cooler (sometimes inside the cooler), there
is a thin slot all the way across the duct(it might be covered with
aluminum tape). Inside this slot, there are guides for a damper to slide
into. You must slide a damper into this slot to block the heated air from
going up into the cooler. This damper is commonly called a "cookiesheet
damper". It is simply a flat piece of sheetmetal with a 1/2 inch right
angle bend in it (used as a handle). The dimensions of the damper is the
same as the inside of your duct. When you insert the damper, use some
aluminum tape to seal over the "handle" of the damper and the opening
In the spring, when you are setting your cooler up for the summer, you must
remove this damper and reseal the slot. At the furnace, there should be a
similar damper that needs to be inserted in spring and removed in winter.
This damper keeps the cooled air from escaping through the furnace.
If you don't have either of these dampers you can have them made easily and
inexpensively at any sheetmetal shop.
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