These are fine as long as they're in the open air. The manual clearly states they should not be placed in a closed cabinet.
I just with the installer would tell you that.
Mine initially kept shutting down from over heating. Had to leave the door open to the cabinet but that was just ugly.
Working fine now, with the cabinet closed, since I cut some airholes in the back of the cabinet and installed a fan to suck the heat out (I also did the laptop cooler thing and moved shelves around to give it the most room possible, including installing a separate shelf with holes in the bottom just for the 622).
The fan sucking the heat out of the cabinet I'm sure is more than enough (but it was the last option I tried, and the least simple).
This is the fan I used:
Home Theater Cooling Home
Very quiet (unlike some others I've tried in the past from Radio Shack). I have it plugged into my switched plug of my audio receiver so it goes on whenever it's on. I still have to leave the door open though when everything's off as the dish receiver never really shuts down and still generates considerable heat. But this solution seemed to work for me.