Timberline Gas Log Heater

I was given a new heater from someone who is deceased. It is a Timberline NVT-11173R. A local fireplace store told me they believe it is a non-vent design but I think it must be a vented design because the instruction plate states "Warning: For installation in a solid fuel burning fireplace". I have tested it (outdoors) and it works fine. Timberline is no longer in existence; I think they were bought our by Vermont Castings. How can I be sure? If it is a non-vented design, I think it requires an oxygen depletion sensor. Is that correct? Is that something that can be added? If you'd prefer to reply to me directly, remove xxxxx and replace it with my user name (ralft).
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