Acceptable Garage Door Balance for 1/2 HP Opener

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!
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HKEK writes:

That's a good question, but in practice 10 or 20 lbs is about as close as you can get in many situations. If the mass of your door is uneven across the panels as you describe, the force will vary at least as much as the panel mass varies. For example, if you have an extra 20 lbs on the top panel, it effectively disappears when the panel goes horizontal. The standard residential door torsion spring mechanism is based on door lift weight being proportionate to lift distance, since the door turns proportionately horizontal. This in turn assumes the door is approximately homogenous, not heavier in some panels than others. Violating that assumption with a heavy panel cannot be compensated for by spring adjustment. You have to make the other panels just as heavy, and install heavier spring(s) for the whole works.
http://www.truetex.com/garage.htm
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Wow! So much detailed info .. bookmarking this for a raining day to read. Thanks Richard.
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On Wed, 17 Oct 2007 12:41:05 -0700, "** Frank **"

The garage door link came at a good time for me :-))
I've been reading Richard's pages on pool repair/remodel.
http://www.truetex.com/pool.htm
-- Oren
Hofstadter's Law - It [a task] always takes longer than you expect, even when you take into account Hofstadter's Law.
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Thanks Oren, another good one from Richard.
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HKEK wrote:

Biggest safety concern is too much weight in the downward position so it falls. If it is a little strong when it is balanced at the midway point for your taste, let off a little so it's more nearly at the 3/4-closed point, but I'd not go past that.
An opener won't have any problem either way, it's only when it's operated manually you have a real issue...
--


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I'm surprised the weight difference is sufficient to create a serious problem. Is it just the glass? Or is the extra metal reinforcement creating (or adding to) the problem?
I can only suggest adding some extra weight to the bottom of the door in order to achieve balance.
I will need to replace my own garage doors in the next year or two and this seems to be another good reason to pass on the windows! The others include cost and a possible break-in vulnerability as discussed in a another recent thread. The glass can help the asthetics but the disadvantages are starting to pile up!
--
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On Oct 17, 12:08 pm, snipped-for-privacy@malch.com (Malcolm Hoar) wrote:

Don't know what other thread you're referring to regarding vulnerabilities, but our HOA recently sent out a news letter with security tips. One that I never thought of involved removing the rope from the mechanism that disengages the opener trolley from the track. When the door is closed, imagine how close that rope is to the door. Now imagine how easy it would be to snag that rope from the outside and disengage the trolley. Don't need windows in the door to do that. Removed the rope from my door the same day. If I ever need to disengage it, I'll grab a stepladder.
Jerry
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(Malcolm Hoar) wrote:

I don't know what other thread he was referring to either. What a difference windows make, so much light across my three car garage area. I'll put windows on every door, including the rental units. Its much easier to crash through the front door or bump the lockset than fool around with the garage window. Living in a safe neighborhood helps.
I had one opener that would automatically open the garage door if someone lifts the door a little bid from the outside. That one didn't have windows. LOL
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Yup, that was the issue raised here, last week, I think.
I am neverthless amazed that an HOA would advocate removing or disabling what is, in fact, a safety device. Their insurers would probably go ballistic.
Now, I'm not sure those ropes have saved a whole ton of lives. But it's a can of worms when it comes to legal liabilities.
I'd keep that rope safe and reinstall it if or when you sell the property.
--
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On Wed, 17 Oct 2007 21:23:01 GMT, snipped-for-privacy@malch.com (Malcolm Hoar) wrote:

In that thread, was the first ever mention about a garage door breach via the rope. I gave thanks to the poster as it had not been mentioned in security tips I've read in the past.

The HOA is better served, by just collecting fees and not giving advice contrary to safety.

My ropes will stay in place, as is. I have to further examine one door as I _believe_ it is on a GFCI circuit. I don't think that is safe.
The rope can get one out of the house, when that is the escape route.
-- Oren
..through the use of electrical or duct tape, achieve the configuration in the photo..
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Yep, our neighborhood had a rash of garage/house breakins where that was the method of entry. They mentioned removing the rope as a means of securing the garage door as a vulnerable entry point, but they obviously did not consider or mention the safety aspects. I may have to reconsider reattaching that rope.

They do a REAL good job on the collecting fees part. Closely followed by sending letters telling you to clean up your weeds. <G>

Yeah, I didn't consider that aspect. If you have a fire in the garage that has disabled the door opener, and the garage door is your only way out, I guess you wouldn't want to take the time, in the dark and smoke and fire, to look for your stepladder so you could disengage the trolley from the track.
Jerry
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Maybe I'm missing something here, but I don't see the opener disconnect as being a major security vulnerability. And the poster said you don't need windows in the door for it to be a security issue? Now, that I totally don't get. Without a window, you'd have to knock out a garage door panel to get to the rope. That assumes of course, the garage door has an opener. And if you;re going to take out a panel, why not just kick out one at ground level and crawl through, where you don;'t care if it has an opener or not?
And then, if you're talking about breaking out a garage door window to get to the rope release, how secure are any other doors/windows? If you have a sliding glass door, or first level window, you can break those for entry easily. I can see this as a security issue if you have the rest of the house well secured and live in an area where break-ins are common, but for the typical house, it;s a non issue.
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Easier just to steal the opener code or bump the door lock. I see break ins through doors and windows, no garage doors yet - maybe just too slow.
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Professional house breakers use the same MO on house after house. If this method of entry is popular in your neighborhood, it would be prudent to be concerned. Other posters have indicated this is a favored entry point in their localities. Apparently, not in all communities and, AFAIK, not in mine. But if you live in an at-risk area it would be sensible to take precautions.
Personally, I wouldn't recommend removing the emergency release rope -- you might just need it one day. But you might make some adjustments that would make it really, really hard for some Bad Guy to activate the thing from the outside.
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HKEK wrote:

That's why you need a 1/2hp motor.
If the springs exactly and perfectly balanced the load, you could lift the door with the motor from your bedside clock.
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Is this a torsion system or open tension springs. I'd say you need a torsion system if it's not already. It sounds like your a bit too tight to me. Although the action you describe is fairly normal. You'll also notice the drums the cables wind up on are tapered. They are designed to give more lift at first and be weaker as the door goes up. I'd say if you get your reinforcements on, then balance it to the point it takes about 10-20 lbs of lift to get it started, you'll be ok.
steve (installed a few, adjusted a few dozen)

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Steve Barker LT writes:

Standard residential door drums are not tapered. Torque declines as the torsion spring unwinds. So does the door lift weight as it bends horizontal.

Tapered drums are used to produce *constant* lift, such as for a straight- up hangar door.
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Since OH Doors (dealer installed) are warranteed, I d take a guess at it and conclude THEY will set them up the way they re supposed to be. Then I d attach the electric opener and push the button. I had 3 they put in at our last house and this method worked fine for me with the Sears 1/2 HP openers I put in.
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