I am setting up a pj in a dedicated media room, in a newly finished house. For some reason the builders put the air vent 150" from the screen wall, and dead center side to side ways. More clearly, almost excatly where I need to mount a hd1000 in order to gett a 100" diag picture. My question is, if I simply turn the vent baffle so it sends the air the other way, will that be enough to protect my pj, or should I think about moving the whole vent? It is on the second floor, and the attic above it is more than head high, so moving it won't be as bad as it could be, but I would sure rather not have to. I hate doing drywall work.

TIA for any thoughts.

Could you live with a slightly smaller or slightly larger image?
Anyway, if the air doesn't actually hit the projector, I think you're mostly good. You might want to use some kind of insulation between the vent and the projector, to make sure there's no additional radiated heat.

I'm speaking from personal experience from my job here:

be very careful of putting a projector close to an air vent. Everything is fun and games in the summer when you have the A/C on, but when hot air starts blowing on the projector when it's trying to get hot air away from it, it'll start shutting off. In one of my buildings projectors start shutting down every October when hvac switches to heat. After 2 years we were finally able to get the vents moved in a couple of the rooms, and those rooms had no more problems. We tried plastic shields to route the hot air away from the projector, but it still had problems.

I'm not saying it would absolutely be a problem for you given your particular model of projector, I'm simply telling you the experience I had (and still have when installers don't pay attention to return locations).

My suggestion is to get a shorter throw lense and moving the projector closer to the screen.

But if you want it in that spot, does the projector not have a zoom on it? Every projector I've ever dealt with has a range (like 15-17') because the projector's zoom can deal with small fluctuations like that.

Thanks for the replies.
My pj (mitsu hd1000) has a limited zoom. For a 100" image it can go from 143" to 174" . My vent is about 146".

Well, if you can move it to the far end of that range then you're over 2 feet from the vent... that would certainly be better than nothing, and might allow you to use some sort of plastic shield to redirect the air flow away from the projector (or get a damper that doesn't shoot air that way).

The ones that I had a problem with were one ceiling tile away from the projector -- that is, the projector would be coming from one ceiling tile and the vent would take up the ceiling tile directly behind that one. Those vents blow air in 4 directions, so there was direct air blowing onto the projector, which turned out to be very bad.