Exhaust setup for light rail/2 hoods

Are there any pictures on here that can help with the design of how the duct work is hooked up to a light rail with extension bar for 2 hoods? Intake would be coming in from outside, which I can do to get it into the room but once in the room I'm having a hard time understanding how to hang the ducting so it doesn't sag when the motor pushes the hood forward. Any help appreciated.

I've seen a guy run his ducting like curtains on the rail.. for lack of a better analogy.
the light mover would either bunch it up at one end and stretch it out on the other, then it would go back the other way and the bunched up side would straighten up and the other side would flex...

Don't have pictures of it..but the idea is pretty basic.

cowell said:

I've seen a guy run his ducting like curtains on the rail.. for lack of a better analogy.
the light mover would either bunch it up at one end and stretch it out on the other, then it would go back the other way and the bunched up side would straighten up and the other side would flex...

Don't have pictures of it..but the idea is pretty basic.

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this is the only way to do it. Use whatever size hood hole you have lets say 6". Get some flex 6" duct work and strap it up, it will retract by itself you just need to guide it.

We run stainless steel safety wire inside the ducts and through the reflectors. Attaches from one side of the room to the other and travels through the reflector roughly an inch away from the bulb. Works flawlessly no sag issues whatsoever. We tried the curtain method, didn't work as well and looked like a giant clusterfuck. With the steel wire you wouldn't even notice it unless you looked real close. Just gotta make sure it's perfectly stretched across and doesn't bind up on the reflectors. We use 8" magnums though so the reflectors have a lot of volume and it's relatively easy to route the steel wire away from any obstructions.

never seen it any other way - but yes, it looked like ass. I agree wholeheartedly and will file away the safety wire idea to tell him next time I see him.

I'm understanding more of the curtain idea than of the other way mentioned. Have any pictures stems&seeds or can you draw it out what it would look like?

i let mine sag a bit but my canopy is flat, and it only sags sorta like a horseshoe from the ceiling, but im gonna re do it like no stems no seeds said he ran a wire thru the duct.. nice!.. heheh

Basically the wire is fixed on both sides of the rail tied tight. When the movers move the reflectors from there farthest point of separation the stretched out flex duct is supported on the inside near the top of the flex duct holding it up. Then when it retracts it'll still hold it in place.

Take your two hands, tie a string to the bottom of your middle finger and attach the other end of the string to the other middle finger. Now move your hands apart until the rope is tight. You'll see the rope has no problem holding itself up cause of tension being pulled at each end, this is how your flex duct should look.

Now move one of those hands closer to the other and the rope droops down because of gravity. Now if only there was something inside that rope that was still tight to hold it up. The rope is your duct, and something inside it to hold it up is the steel wire and your hands are the 2 reflectors. Ya understand?

The something inside, when you move one of those hands closer, would have to expand and contract and still be rigid, like telescoping sort of like an old car antenna, otherwise it wouldn't work.

Edit: Never mind, I understand now. The wire stays rigid. The duct work would expand and contract on the wire, but not sag.

stems&seeds said:

We run stainless steel safety wire inside the ducts and through the reflectors. Attaches from one side of the room to the other and travels through the reflector roughly an inch away from the bulb. Works flawlessly no sag issues whatsoever. We tried the curtain method, didn't work as well and looked like a giant clusterfuck. With the steel wire you wouldn't even notice it unless you looked real close. Just gotta make sure it's perfectly stretched across and doesn't bind up on the reflectors. We use 8" magnums though so the reflectors have a lot of volume and it's relatively easy to route the steel wire away from any obstructions.

Click to expand...

Excellent idea! Thanks!