If someone cobbled that up to work for propane, it would be scary.
Look at the link posted earlier for the diesel version and look at the picture in this link:
SJ23 Tech Tip C07 - Force 10 Bulkhead Heater and Vented Propane Locker.
Does your burner have a cup to pour alcohol in, or does it look like the burner in the link in this post?
In any event, my guess is that this is a diesel version of the heater. I think I would open the valve on the heater long enough to see if there is any pressure left. If there is and liquid flows into a preheater cup then you know it's a diesel heater. If there is no pressure, then time to take down the bottle and start investigating. It doesn't look like there's any way to pressurize it. It looks like it stops delivering fuel when the bottle is still nearly half full. It could be a masterwork of engineering that works properly, but it is not stock and unless the person that built it can tell you what he did, the only other way is to take it apart to see how it works, then throw it away and find a more appropriate pressure tank.
(or pay someone to look at it)