Moved into a completely renovated house and there's a Majco G336L (vented) propane gas fireplace in the house. A service guy came by from the local gas fireplace retailer and said that the fireplace wasn't venting properly (the fire goes out after a minute or so). Apparently whoever renovated the house had installed a simple range vent/hood instead of a real fireplace vent.

He said I need a "five-eight" vent. He checked and said that Majestic (which took over Majco) doesn't make those any more and he can't find a replacement.

I don't know what a "five-eight" vent is. Can someone explain that to me and give me leads as to where I might get one?