Liftmaster 3800 sensor stops on way up? HELP

[boyAND1]

I am confused here and hoping the GJ wealth of knowledge can help me.

I hired a guy to install a liftmaster 3800 opener. The overhead door is 18x9 and has a 10 ft ceiling. There is a low headroom track (double track). After he installed i noticed 2 things.

1. When the sensors are interrupted during the door travel down, it does not stop. It stops when the door is going up instead.
2. The door lock locks after the door is all the way up instead of when it has closed.

I hoped this was just a switch of some wires but I could not figure it out. So I called the guy who installed it and told him it was wrong. Now he looked at it again and he calls me at work and says this cannot be fixed after a call he made to liftmaster. You should not be using a jackshaft opener in this situation and there is no way to get this to work the other way around b/c the shaft turns the wrong way. He said something about not wanting the door slamming on someone too but I didn't get all of it b/c he was saying he cannot install the opener again for liability reason and the steam was blowing out of my ears by then. Can anyone tell me what is going on?

The door has a torsion spring above the door with a shaft that the opener is connected to. Why won't this work. I didn't want an opener hanging from the middle of my ceiling.

 

[pattenp]

I believe the double track low clearance requires the drums to wind the cable up from the front of the drums instead of the rear of the drum. Which way do your cables wind on the drums? For the 3800 to work properly the cables need to travel up the back of the drums between the drum and wall. I hope this is clear.

Edit: I think the solution is to mount the opener flat on the ceiling. This will rotate the opener and make the drive direction correct. You will have to rig a pulley on the ceiling for the manual door release. This is only if the cables wind up from the front of the drums.

 

[GeorgiaHybrid]

It doesn't make any difference where you mount the opener, it will not work with the drum cable on the wrong side of the drum. whether it is on the roof or the wall, the opener will still turn the same direction.

I am also not sure about the two track low headroom system but there is a way around that by converting to a specialized single track system.

 

[pattenp]

This is not correct. Positioning as I suggest on the ceiling will change the rotation orientation to be correct with the cable feeding from the front of the drums.

It doesn't make any difference where you mount the opener, it will not work with the drum cable on the wrong side of the drum. whether it is on the roof or the wall, the opener will still turn the same direction.

I am also not sure about the two track low headroom system but there is a way around that by converting to a specialized single track system.

 

[boyAND1]

I remember why he said he didnt want to change the direction of the drum was that the door would not open as high. Seems to make some sense.
Thanks for the ceiling idea patten. Will probably give that a try tomorrow. Is that what you had to do judging from the picture?

 

[pattenp]

The picture of the 3800 on the ceiling was photoshopped to show you what I was talking about. My 3800 is mounted the standard way on the wall.

Here's a better explaination of why mounting the opener on the ceiling corrects the problem from the cables feeding from the front of the drums.


This explanation is with the cables fed the standard way from the back of the drums.

To set a point of reference when determining rotation I will use the opener being mounted on the left end of the spring shaft. When looking at the right hand end of the opener drive shaft when lowering the door the opener drive shaft is turning clockwise and when raising the door it turns counter clockwise. The rotation when looking at the left end of the opener drive shaft will be the opposite. This is why the opener can be mounted on either the left end or the right end of the spring shaft and maintain it’s correct orientation as to what’s up and what’s down. When the cables are fed from the front of the drums the opener’s internal sensors are now thinking the door is going up when in fact it is going down and when the door is going down the opener thinks it’s going up. By flipping the opener to drive from the left side of the opener while keeping the opener on the left end of the spring drive shaft will put the opener back into the correct orientation, so up is now up and down is now down to the opener. The only way to accomplish this is to mount the opener inverted on the ceiling.

Disclaimer: In theory this should work, but I have not done this and there may be other issues with setting travel limits to get the door to fully open or close.