I am installing electric openers on two new (sectional) garage doors.
The doors are top-of-the-line models from Overhead Door, dealer
installed. I have always understood that the weight of the garage
doors must be counter balanced by the springs. Makes sense.
These doors have a top panel with insulated glass. While the top panel
is significantly heavier than all the others, it is also the weakest;
therefore, as shown in the instructions, a metal reinforcement plate
is added for attaching the opener and a continuous angle iron
stiffener is added completely across the top of the panel to prevent
the panel from flexing.
Trouble is, how can one get such a door properly balanced? When the
recommended tension springs are installed and adjusted such that the
door stays down and can be lifted without much effort, the door takes
off and must be held back as the top panel moves out of the vertical
track onto the overhead (horizontal) track section! Makes sense, since
the spring has a constant force rate whereas the door does not.
I see potential safety problems with this situation regardless of
whether the door is operated manually or with an electric opener (load
sensitivity, reversing and such).
In an ideal situation balance would mean "throughout the entire
range"; in the example given in the instruction booklet, balance is
check at the halfway point. I suppose I could add weight to the bottom
of the door and go with heavier springs to obtain balance throughout
the range, but when am I close enough?
If the door balances at the half-way point but it takes X pounds lift
it from the closed position and Y pounds to pull it down, what are
safe/acceptable values for X and Y with the electric door opener?
Is there an engineer at Chamberlain that is willing to go on record
here? - Thanks!